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/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at *//from w w w . java 2s . com * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.primftpd.util; import java.io.UnsupportedEncodingException; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.util.Arrays; import java.util.Locale; import java.util.regex.Pattern; /** * <p>Operations on {@link java.lang.String} that are * {@code null} safe.</p> * * <ul> * <li><b>IsEmpty/IsBlank</b> * - checks if a String contains text</li> * <li><b>Trim/Strip</b> * - removes leading and trailing whitespace</li> * <li><b>Equals</b> * - compares two strings null-safe</li> * <li><b>startsWith</b> * - check if a String starts with a prefix null-safe</li> * <li><b>endsWith</b> * - check if a String ends with a suffix null-safe</li> * <li><b>IndexOf/LastIndexOf/Contains</b> * - null-safe index-of checks * <li><b>IndexOfAny/LastIndexOfAny/IndexOfAnyBut/LastIndexOfAnyBut</b> * - index-of any of a set of Strings</li> * <li><b>ContainsOnly/ContainsNone/ContainsAny</b> * - does String contains only/none/any of these characters</li> * <li><b>Substring/Left/Right/Mid</b> * - null-safe substring extractions</li> * <li><b>SubstringBefore/SubstringAfter/SubstringBetween</b> * - substring extraction relative to other strings</li> * <li><b>Split/Join</b> * - splits a String into an array of substrings and vice versa</li> * <li><b>Remove/Delete</b> * - removes part of a String</li> * <li><b>Replace/Overlay</b> * - Searches a String and replaces one String with another</li> * <li><b>Chomp/Chop</b> * - removes the last part of a String</li> * <li><b>LeftPad/RightPad/Center/Repeat</b> * - pads a String</li> * <li><b>UpperCase/LowerCase/SwapCase/Capitalize/Uncapitalize</b> * - changes the case of a String</li> * <li><b>CountMatches</b> * - counts the number of occurrences of one String in another</li> * <li><b>IsAlpha/IsNumeric/IsWhitespace/IsAsciiPrintable</b> * - checks the characters in a String</li> * <li><b>DefaultString</b> * - protects against a null input String</li> * <li><b>Reverse/ReverseDelimited</b> * - reverses a String</li> * <li><b>Abbreviate</b> * - abbreviates a string using ellipsis</li> * <li><b>Difference</b> * - compares Strings and reports on their differences</li> * <li><b>LevenshteinDistance</b> * - the number of changes needed to change one String into another</li> * </ul> * * <p>The {@code StringUtils} class defines certain words related to * String handling.</p> * * <ul> * <li>null - {@code null}</li> * <li>empty - a zero-length string ({@code ""})</li> * <li>space - the space character ({@code ' '}, char 32)</li> * <li>whitespace - the characters defined by {@link Character#isWhitespace(char)}</li> * <li>trim - the characters <= 32 as in {@link String#trim()}</li> * </ul> * * <p>{@code StringUtils} handles {@code null} input Strings quietly. * That is to say that a {@code null} input will return {@code null}. * Where a {@code boolean} or {@code int} is being returned * details vary by method.</p> * * <p>A side effect of the {@code null} handling is that a * {@code NullPointerException} should be considered a bug in * {@code StringUtils}.</p> * * <p>Methods in this class give sample code to explain their operation. * The symbol {@code *} is used to indicate any input including {@code null}.</p> * * <p>#ThreadSafe#</p> * @see java.lang.String * @since 1.0 * @version $Id: StringUtils.java 1199894 2011-11-09 17:53:59Z ggregory $ */ //@Immutable public class StringUtils { // Performance testing notes (JDK 1.4, Jul03, scolebourne) // Whitespace: // Character.isWhitespace() is faster than WHITESPACE.indexOf() // where WHITESPACE is a string of all whitespace characters // // Character access: // String.charAt(n) versus toCharArray(), then array[n] // String.charAt(n) is about 15% worse for a 10K string // They are about equal for a length 50 string // String.charAt(n) is about 4 times better for a length 3 string // String.charAt(n) is best bet overall // // Append: // String.concat about twice as fast as StringBuffer.append // (not sure who tested this) /** * The empty String {@code ""}. * @since 2.0 */ public static final String EMPTY = ""; /** * Represents a failed index search. * @since 2.1 */ public static final int INDEX_NOT_FOUND = -1; /** * <p>The maximum size to which the padding constant(s) can expand.</p> */ private static final int PAD_LIMIT = 8192; /** * A regex pattern for recognizing blocks of whitespace characters. */ private static final Pattern WHITESPACE_BLOCK = Pattern.compile("\\s+"); /** * <p>{@code StringUtils} instances should NOT be constructed in * standard programming. Instead, the class should be used as * {@code StringUtils.trim(" foo ");}.</p> * * <p>This constructor is public to permit tools that require a JavaBean * instance to operate.</p> */ public StringUtils() { super(); } // Empty checks //----------------------------------------------------------------------- /** * <p>Checks if a CharSequence is empty ("") or null.</p> * * <pre> * StringUtils.isEmpty(null) = true * StringUtils.isEmpty("") = true * StringUtils.isEmpty(" ") = false * StringUtils.isEmpty("bob") = false * StringUtils.isEmpty(" bob ") = false * </pre> * * <p>NOTE: This method changed in Lang version 2.0. * It no longer trims the CharSequence. * That functionality is available in isBlank().</p> * * @param cs the CharSequence to check, may be null * @return {@code true} if the CharSequence is empty or null * @since 3.0 Changed signature from isEmpty(String) to isEmpty(CharSequence) */ public static boolean isEmpty(CharSequence cs) { return cs == null || cs.length() == 0; } /** * <p>Checks if a CharSequence is not empty ("") and not null.</p> * * <pre> * StringUtils.isNotEmpty(null) = false * StringUtils.isNotEmpty("") = false * StringUtils.isNotEmpty(" ") = true * StringUtils.isNotEmpty("bob") = true * StringUtils.isNotEmpty(" bob ") = true * </pre> * * @param cs the CharSequence to check, may be null * @return {@code true} if the CharSequence is not empty and not null * @since 3.0 Changed signature from isNotEmpty(String) to isNotEmpty(CharSequence) */ public static boolean isNotEmpty(CharSequence cs) { return !StringUtils.isEmpty(cs); } /** * <p>Checks if a CharSequence is whitespace, empty ("") or null.</p> * * <pre> * StringUtils.isBlank(null) = true * StringUtils.isBlank("") = true * StringUtils.isBlank(" ") = true * StringUtils.isBlank("bob") = false * StringUtils.isBlank(" bob ") = false * </pre> * * @param cs the CharSequence to check, may be null * @return {@code true} if the CharSequence is null, empty or whitespace * @since 2.0 * @since 3.0 Changed signature from isBlank(String) to isBlank(CharSequence) */ public static boolean isBlank(CharSequence cs) { int strLen; if (cs == null || (strLen = cs.length()) == 0) { return true; } for (int i = 0; i < strLen; i++) { if (Character.isWhitespace(cs.charAt(i)) == false) { return false; } } return true; } /** * <p>Checks if a CharSequence is not empty (""), not null and not whitespace only.</p> * * <pre> * StringUtils.isNotBlank(null) = false * StringUtils.isNotBlank("") = false * StringUtils.isNotBlank(" ") = false * StringUtils.isNotBlank("bob") = true * StringUtils.isNotBlank(" bob ") = true * </pre> * * @param cs the CharSequence to check, may be null * @return {@code true} if the CharSequence is * not empty and not null and not whitespace * @since 2.0 * @since 3.0 Changed signature from isNotBlank(String) to isNotBlank(CharSequence) */ public static boolean isNotBlank(CharSequence cs) { return !StringUtils.isBlank(cs); } // Trim //----------------------------------------------------------------------- /** * <p>Removes control characters (char <= 32) from both * ends of this String, handling {@code null} by returning * {@code null}.</p> * * <p>The String is trimmed using {@link String#trim()}. * Trim removes start and end characters <= 32. * To strip whitespace use {@link #strip(String)}.</p> * * <p>To trim your choice of characters, use the * {@link #strip(String, String)} methods.</p> * * <pre> * StringUtils.trim(null) = null * StringUtils.trim("") = "" * StringUtils.trim(" ") = "" * StringUtils.trim("abc") = "abc" * StringUtils.trim(" abc ") = "abc" * </pre> * * @param str the String to be trimmed, may be null * @return the trimmed string, {@code null} if null String input */ public static String trim(String str) { return str == null ? null : str.trim(); } /** * <p>Removes control characters (char <= 32) from both * ends of this String returning {@code null} if the String is * empty ("") after the trim or if it is {@code null}. * * <p>The String is trimmed using {@link String#trim()}. * Trim removes start and end characters <= 32. * To strip whitespace use {@link #stripToNull(String)}.</p> * * <pre> * StringUtils.trimToNull(null) = null * StringUtils.trimToNull("") = null * StringUtils.trimToNull(" ") = null * StringUtils.trimToNull("abc") = "abc" * StringUtils.trimToNull(" abc ") = "abc" * </pre> * * @param str the String to be trimmed, may be null * @return the trimmed String, * {@code null} if only chars <= 32, empty or null String input * @since 2.0 */ public static String trimToNull(String str) { String ts = trim(str); return isEmpty(ts) ? null : ts; } /** * <p>Removes control characters (char <= 32) from both * ends of this String returning an empty String ("") if the String * is empty ("") after the trim or if it is {@code null}. * * <p>The String is trimmed using {@link String#trim()}. * Trim removes start and end characters <= 32. * To strip whitespace use {@link #stripToEmpty(String)}.</p> * * <pre> * StringUtils.trimToEmpty(null) = "" * StringUtils.trimToEmpty("") = "" * StringUtils.trimToEmpty(" ") = "" * StringUtils.trimToEmpty("abc") = "abc" * StringUtils.trimToEmpty(" abc ") = "abc" * </pre> * * @param str the String to be trimmed, may be null * @return the trimmed String, or an empty String if {@code null} input * @since 2.0 */ public static String trimToEmpty(String str) { return str == null ? EMPTY : str.trim(); } // Stripping //----------------------------------------------------------------------- /** * <p>Strips whitespace from the start and end of a String.</p> * * <p>This is similar to {@link #trim(String)} but removes whitespace. * Whitespace is defined by {@link Character#isWhitespace(char)}.</p> * * <p>A {@code null} input String returns {@code null}.</p> * * <pre> * StringUtils.strip(null) = null * StringUtils.strip("") = "" * StringUtils.strip(" ") = "" * StringUtils.strip("abc") = "abc" * StringUtils.strip(" abc") = "abc" * StringUtils.strip("abc ") = "abc" * StringUtils.strip(" abc ") = "abc" * StringUtils.strip(" ab c ") = "ab c" * </pre> * * @param str the String to remove whitespace from, may be null * @return the stripped String, {@code null} if null String input */ public static String strip(String str) { return strip(str, null); } /** * <p>Strips whitespace from the start and end of a String returning * {@code null} if the String is empty ("") after the strip.</p> * * <p>This is similar to {@link #trimToNull(String)} but removes whitespace. * Whitespace is defined by {@link Character#isWhitespace(char)}.</p> * * <pre> * StringUtils.stripToNull(null) = null * StringUtils.stripToNull("") = null * StringUtils.stripToNull(" ") = null * StringUtils.stripToNull("abc") = "abc" * StringUtils.stripToNull(" abc") = "abc" * StringUtils.stripToNull("abc ") = "abc" * StringUtils.stripToNull(" abc ") = "abc" * StringUtils.stripToNull(" ab c ") = "ab c" * </pre> * * @param str the String to be stripped, may be null * @return the stripped String, * {@code null} if whitespace, empty or null String input * @since 2.0 */ public static String stripToNull(String str) { if (str == null) { return null; } str = strip(str, null); return str.length() == 0 ? null : str; } /** * <p>Strips whitespace from the start and end of a String returning * an empty String if {@code null} input.</p> * * <p>This is similar to {@link #trimToEmpty(String)} but removes whitespace. * Whitespace is defined by {@link Character#isWhitespace(char)}.</p> * * <pre> * StringUtils.stripToEmpty(null) = "" * StringUtils.stripToEmpty("") = "" * StringUtils.stripToEmpty(" ") = "" * StringUtils.stripToEmpty("abc") = "abc" * StringUtils.stripToEmpty(" abc") = "abc" * StringUtils.stripToEmpty("abc ") = "abc" * StringUtils.stripToEmpty(" abc ") = "abc" * StringUtils.stripToEmpty(" ab c ") = "ab c" * </pre> * * @param str the String to be stripped, may be null * @return the trimmed String, or an empty String if {@code null} input * @since 2.0 */ public static String stripToEmpty(String str) { return str == null ? EMPTY : strip(str, null); } /** * <p>Strips any of a set of characters from the start and end of a String. * This is similar to {@link String#trim()} but allows the characters * to be stripped to be controlled.</p> * * <p>A {@code null} input String returns {@code null}. * An empty string ("") input returns the empty string.</p> * * <p>If the stripChars String is {@code null}, whitespace is * stripped as defined by {@link Character#isWhitespace(char)}. * Alternatively use {@link #strip(String)}.</p> * * <pre> * StringUtils.strip(null, *) = null * StringUtils.strip("", *) = "" * StringUtils.strip("abc", null) = "abc" * StringUtils.strip(" abc", null) = "abc" * StringUtils.strip("abc ", null) = "abc" * StringUtils.strip(" abc ", null) = "abc" * StringUtils.strip(" abcyx", "xyz") = " abc" * </pre> * * @param str the String to remove characters from, may be null * @param stripChars the characters to remove, null treated as whitespace * @return the stripped String, {@code null} if null String input */ public static String strip(String str, String stripChars) { if (isEmpty(str)) { return str; } str = stripStart(str, stripChars); return stripEnd(str, stripChars); } /** * <p>Strips any of a set of characters from the start of a String.</p> * * <p>A {@code null} input String returns {@code null}. * An empty string ("") input returns the empty string.</p> * * <p>If the stripChars String is {@code null}, whitespace is * stripped as defined by {@link Character#isWhitespace(char)}.</p> * * <pre> * StringUtils.stripStart(null, *) = null * StringUtils.stripStart("", *) = "" * StringUtils.stripStart("abc", "") = "abc" * StringUtils.stripStart("abc", null) = "abc" * StringUtils.stripStart(" abc", null) = "abc" * StringUtils.stripStart("abc ", null) = "abc " * StringUtils.stripStart(" abc ", null) = "abc " * StringUtils.stripStart("yxabc ", "xyz") = "abc " * </pre> * * @param str the String to remove characters from, may be null * @param stripChars the characters to remove, null treated as whitespace * @return the stripped String, {@code null} if null String input */ public static String stripStart(String str, String stripChars) { int strLen; if (str == null || (strLen = str.length()) == 0) { return str; } int start = 0; if (stripChars == null) { while (start != strLen && Character.isWhitespace(str.charAt(start))) { start++; } } else if (stripChars.length() == 0) { return str; } else { while (start != strLen && stripChars.indexOf(str.charAt(start)) != INDEX_NOT_FOUND) { start++; } } return str.substring(start); } /** * <p>Strips any of a set of characters from the end of a String.</p> * * <p>A {@code null} input String returns {@code null}. * An empty string ("") input returns the empty string.</p> * * <p>If the stripChars String is {@code null}, whitespace is * stripped as defined by {@link Character#isWhitespace(char)}.</p> * * <pre> * StringUtils.stripEnd(null, *) = null * StringUtils.stripEnd("", *) = "" * StringUtils.stripEnd("abc", "") = "abc" * StringUtils.stripEnd("abc", null) = "abc" * StringUtils.stripEnd(" abc", null) = " abc" * StringUtils.stripEnd("abc ", null) = "abc" * StringUtils.stripEnd(" abc ", null) = " abc" * StringUtils.stripEnd(" abcyx", "xyz") = " abc" * StringUtils.stripEnd("120.00", ".0") = "12" * </pre> * * @param str the String to remove characters from, may be null * @param stripChars the set of characters to remove, null treated as whitespace * @return the stripped String, {@code null} if null String input */ public static String stripEnd(String str, String stripChars) { int end; if (str == null || (end = str.length()) == 0) { return str; } if (stripChars == null) { while (end != 0 && Character.isWhitespace(str.charAt(end - 1))) { end--; } } else if (stripChars.length() == 0) { return str; } else { while (end != 0 && stripChars.indexOf(str.charAt(end - 1)) != INDEX_NOT_FOUND) { end--; } } return str.substring(0, end); } // StripAll //----------------------------------------------------------------------- /** * <p>Strips whitespace from the start and end of every String in an array. * Whitespace is defined by {@link Character#isWhitespace(char)}.</p> * * <p>A new array is returned each time, except for length zero. * A {@code null} array will return {@code null}. * An empty array will return itself. * A {@code null} array entry will be ignored.</p> * * <pre> * StringUtils.stripAll(null) = null * StringUtils.stripAll([]) = [] * StringUtils.stripAll(["abc", " abc"]) = ["abc", "abc"] * StringUtils.stripAll(["abc ", null]) = ["abc", null] * </pre> * * @param strs the array to remove whitespace from, may be null * @return the stripped Strings, {@code null} if null array input */ public static String[] stripAll(String... strs) { return stripAll(strs, null); } /** * <p>Strips any of a set of characters from the start and end of every * String in an array.</p> * Whitespace is defined by {@link Character#isWhitespace(char)}.</p> * * <p>A new array is returned each time, except for length zero. * A {@code null} array will return {@code null}. * An empty array will return itself. * A {@code null} array entry will be ignored. * A {@code null} stripChars will strip whitespace as defined by * {@link Character#isWhitespace(char)}.</p> * * <pre> * StringUtils.stripAll(null, *) = null * StringUtils.stripAll([], *) = [] * StringUtils.stripAll(["abc", " abc"], null) = ["abc", "abc"] * StringUtils.stripAll(["abc ", null], null) = ["abc", null] * StringUtils.stripAll(["abc ", null], "yz") = ["abc ", null] * StringUtils.stripAll(["yabcz", null], "yz") = ["abc", null] * </pre> * * @param strs the array to remove characters from, may be null * @param stripChars the characters to remove, null treated as whitespace * @return the stripped Strings, {@code null} if null array input */ public static String[] stripAll(String[] strs, String stripChars) { int strsLen; if (strs == null || (strsLen = strs.length) == 0) { return strs; } String[] newArr = new String[strsLen]; for (int i = 0; i < strsLen; i++) { newArr[i] = strip(strs[i], stripChars); } return newArr; } /** * <p>Removes diacritics (~= accents) from a string. The case will not be altered.</p> * <p>For instance, 'à' will be replaced by 'a'.</p> * <p>Note that ligatures will be left as is.</p> * * <p>This method will use the first available implementation of: * Java 6's {@link java.text.Normalizer}, Java 1.3–1.5's {@code sun.text.Normalizer}</p> * * <pre> * StringUtils.stripAccents(null) = null * StringUtils.stripAccents("") = "" * StringUtils.stripAccents("control") = "control" * StringUtils.stripAccents("éclair") = "eclair" * </pre> * * @param input String to be stripped * @return input text with diacritics removed * * @since 3.0 */ // See also Lucene's ASCIIFoldingFilter (Lucene 2.9) that replaces accented characters by their unaccented equivalent (and uncommitted bug fix: https://issues.apache.org/jira/browse/LUCENE-1343?focusedCommentId=12858907&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#action_12858907). public static String stripAccents(String input) { if(input == null) { return null; } try { String result = null; if (InitStripAccents.java6NormalizeMethod != null) { result = removeAccentsJava6(input); } else if (InitStripAccents.sunDecomposeMethod != null) { result = removeAccentsSUN(input); } else { throw new UnsupportedOperationException( "The stripAccents(CharSequence) method requires at least" +" Java6, but got: "+InitStripAccents.java6Exception +"; or a Sun JVM: "+InitStripAccents.sunException); } // Note that none of the above methods correctly remove ligatures... return result; } catch(IllegalArgumentException iae) { throw new RuntimeException("IllegalArgumentException occurred", iae); } catch(IllegalAccessException iae) { throw new RuntimeException("IllegalAccessException occurred", iae); } catch(InvocationTargetException ite) { throw new RuntimeException("InvocationTargetException occurred", ite); } catch(SecurityException se) { throw new RuntimeException("SecurityException occurred", se); } } /** * Use {@code java.text.Normalizer#normalize(CharSequence, Normalizer.Form)} * (but be careful, this class exists in Java 1.3, with an entirely different meaning!) * * @param text the text to be processed * @return the processed string * @throws IllegalAccessException may be thrown by a reflection call * @throws InvocationTargetException if a reflection call throws an exception * @throws IllegalStateException if the {@code Normalizer} class is not available */ private static String removeAccentsJava6(CharSequence text) throws IllegalAccessException, InvocationTargetException { /* String decomposed = java.text.Normalizer.normalize(CharSequence, Normalizer.Form.NFD); return java6Pattern.matcher(decomposed).replaceAll("");//$NON-NLS-1$ */ if (InitStripAccents.java6NormalizeMethod == null || InitStripAccents.java6NormalizerFormNFD == null) { throw new IllegalStateException("java.text.Normalizer is not available", InitStripAccents.java6Exception); } String result; result = (String) InitStripAccents.java6NormalizeMethod.invoke(null, new Object[] {text, InitStripAccents.java6NormalizerFormNFD}); result = InitStripAccents.java6Pattern.matcher(result).replaceAll("");//$NON-NLS-1$ return result; } /** * Use {@code sun.text.Normalizer#decompose(String, boolean, int)} * * @param text the text to be processed * @return the processed string * @throws IllegalAccessException may be thrown by a reflection call * @throws InvocationTargetException if a reflection call throws an exception * @throws IllegalStateException if the {@code Normalizer} class is not available */ private static String removeAccentsSUN(CharSequence text) throws IllegalAccessException, InvocationTargetException { /* String decomposed = sun.text.Normalizer.decompose(text, false, 0); return sunPattern.matcher(decomposed).replaceAll("");//$NON-NLS-1$ */ if (InitStripAccents.sunDecomposeMethod == null) { throw new IllegalStateException("sun.text.Normalizer is not available", InitStripAccents.sunException); } String result; result = (String) InitStripAccents.sunDecomposeMethod.invoke(null, new Object[] {text, Boolean.FALSE, Integer.valueOf(0)}); result = InitStripAccents.sunPattern.matcher(result).replaceAll("");//$NON-NLS-1$ return result; } // IOD container for stripAccent() initialisation private static class InitStripAccents { // SUN internal, Java 1.3 -> Java 5 private static final Throwable sunException; private static final Method sunDecomposeMethod; private static final Pattern sunPattern = Pattern.compile("\\p{InCombiningDiacriticalMarks}+");//$NON-NLS-1$ // Java 6+ private static final Throwable java6Exception; private static final Method java6NormalizeMethod; private static final Object java6NormalizerFormNFD; private static final Pattern java6Pattern = sunPattern; static { // Set up defaults for final static fields Object _java6NormalizerFormNFD = null; Method _java6NormalizeMethod = null; Method _sunDecomposeMethod = null; Throwable _java6Exception = null; Throwable _sunException = null; try { // java.text.Normalizer.normalize(CharSequence, Normalizer.Form.NFD); // Be careful not to get Java 1.3 java.text.Normalizer! Class<?> normalizerFormClass = Thread.currentThread().getContextClassLoader() .loadClass("java.text.Normalizer$Form");//$NON-NLS-1$ _java6NormalizerFormNFD = normalizerFormClass.getField("NFD").get(null);//$NON-NLS-1$ Class<?> normalizerClass = Thread.currentThread().getContextClassLoader() .loadClass("java.text.Normalizer");//$NON-NLS-1$ _java6NormalizeMethod = normalizerClass.getMethod("normalize",//$NON-NLS-1$ new Class[] {CharSequence.class, normalizerFormClass});//$NON-NLS-1$ } catch (Exception e1) { // Only check for Sun method if Java 6 method is not available _java6Exception = e1; try { // sun.text.Normalizer.decompose(text, false, 0); Class<?> normalizerClass = Thread.currentThread().getContextClassLoader() .loadClass("sun.text.Normalizer");//$NON-NLS-1$ _sunDecomposeMethod = normalizerClass.getMethod("decompose",//$NON-NLS-1$ new Class[] {String.class, Boolean.TYPE, Integer.TYPE});//$NON-NLS-1$ } catch (Exception e2) { _sunException = e2; } } // Set up final static fields java6Exception = _java6Exception; java6NormalizerFormNFD = _java6NormalizerFormNFD; java6NormalizeMethod = _java6NormalizeMethod; sunException = _sunException; sunDecomposeMethod = _sunDecomposeMethod; } } // Equals //----------------------------------------------------------------------- /** * <p>Compares two CharSequences, returning {@code true} if they are equal.</p> * * <p>{@code null}s are handled without exceptions. Two {@code null} * references are considered to be equal. The comparison is case sensitive.</p> * * <pre> * StringUtils.equals(null, null) = true * StringUtils.equals(null, "abc") = false * StringUtils.equals("abc", null) = false * StringUtils.equals("abc", "abc") = true * StringUtils.equals("abc", "ABC") = false * </pre> * * @see java.lang.String#equals(Object) * @param cs1 the first CharSequence, may be null * @param cs2 the second CharSequence, may be null * @return {@code true} if the CharSequences are equal, case sensitive, or * both {@code null} * @since 3.0 Changed signature from equals(String, String) to equals(CharSequence, CharSequence) */ public static boolean equals(CharSequence cs1, CharSequence cs2) { return cs1 == null ? cs2 == null : cs1.equals(cs2); } // Substring //----------------------------------------------------------------------- /** * <p>Gets a substring from the specified String avoiding exceptions.</p> * * <p>A negative start position can be used to start {@code n} * characters from the end of the String.</p> * * <p>A {@code null} String will return {@code null}. * An empty ("") String will return "".</p> * * <pre> * StringUtils.substring(null, *) = null * StringUtils.substring("", *) = "" * StringUtils.substring("abc", 0) = "abc" * StringUtils.substring("abc", 2) = "c" * StringUtils.substring("abc", 4) = "" * StringUtils.substring("abc", -2) = "bc" * StringUtils.substring("abc", -4) = "abc" * </pre> * * @param str the String to get the substring from, may be null * @param start the position to start from, negative means * count back from the end of the String by this many characters * @return substring from start position, {@code null} if null String input */ public static String substring(String str, int start) { if (str == null) { return null; } // handle negatives, which means last n characters if (start < 0) { start = str.length() + start; // remember start is negative } if (start < 0) { start = 0; } if (start > str.length()) { return EMPTY; } return str.substring(start); } /** * <p>Gets a substring from the specified String avoiding exceptions.</p> * * <p>A negative start position can be used to start/end {@code n} * characters from the end of the String.</p> * * <p>The returned substring starts with the character in the {@code start} * position and ends before the {@code end} position. All position counting is * zero-based -- i.e., to start at the beginning of the string use * {@code start = 0}. Negative start and end positions can be used to * specify offsets relative to the end of the String.</p> * * <p>If {@code start} is not strictly to the left of {@code end}, "" * is returned.</p> * * <pre> * StringUtils.substring(null, *, *) = null * StringUtils.substring("", * , *) = ""; * StringUtils.substring("abc", 0, 2) = "ab" * StringUtils.substring("abc", 2, 0) = "" * StringUtils.substring("abc", 2, 4) = "c" * StringUtils.substring("abc", 4, 6) = "" * StringUtils.substring("abc", 2, 2) = "" * StringUtils.substring("abc", -2, -1) = "b" * StringUtils.substring("abc", -4, 2) = "ab" * </pre> * * @param str the String to get the substring from, may be null * @param start the position to start from, negative means * count back from the end of the String by this many characters * @param end the position to end at (exclusive), negative means * count back from the end of the String by this many characters * @return substring from start position to end position, * {@code null} if null String input */ public static String substring(String str, int start, int end) { if (str == null) { return null; } // handle negatives if (end < 0) { end = str.length() + end; // remember end is negative } if (start < 0) { start = str.length() + start; // remember start is negative } // check length next if (end > str.length()) { end = str.length(); } // if start is greater than end, return "" if (start > end) { return EMPTY; } if (start < 0) { start = 0; } if (end < 0) { end = 0; } return str.substring(start, end); } // Left/Right/Mid //----------------------------------------------------------------------- /** * <p>Gets the leftmost {@code len} characters of a String.</p> * * <p>If {@code len} characters are not available, or the * String is {@code null}, the String will be returned without * an exception. An empty String is returned if len is negative.</p> * * <pre> * StringUtils.left(null, *) = null * StringUtils.left(*, -ve) = "" * StringUtils.left("", *) = "" * StringUtils.left("abc", 0) = "" * StringUtils.left("abc", 2) = "ab" * StringUtils.left("abc", 4) = "abc" * </pre> * * @param str the String to get the leftmost characters from, may be null * @param len the length of the required String * @return the leftmost characters, {@code null} if null String input */ public static String left(String str, int len) { if (str == null) { return null; } if (len < 0) { return EMPTY; } if (str.length() <= len) { return str; } return str.substring(0, len); } /** * <p>Gets the rightmost {@code len} characters of a String.</p> * * <p>If {@code len} characters are not available, or the String * is {@code null}, the String will be returned without an * an exception. An empty String is returned if len is negative.</p> * * <pre> * StringUtils.right(null, *) = null * StringUtils.right(*, -ve) = "" * StringUtils.right("", *) = "" * StringUtils.right("abc", 0) = "" * StringUtils.right("abc", 2) = "bc" * StringUtils.right("abc", 4) = "abc" * </pre> * * @param str the String to get the rightmost characters from, may be null * @param len the length of the required String * @return the rightmost characters, {@code null} if null String input */ public static String right(String str, int len) { if (str == null) { return null; } if (len < 0) { return EMPTY; } if (str.length() <= len) { return str; } return str.substring(str.length() - len); } /** * <p>Gets {@code len} characters from the middle of a String.</p> * * <p>If {@code len} characters are not available, the remainder * of the String will be returned without an exception. If the * String is {@code null}, {@code null} will be returned. * An empty String is returned if len is negative or exceeds the * length of {@code str}.</p> * * <pre> * StringUtils.mid(null, *, *) = null * StringUtils.mid(*, *, -ve) = "" * StringUtils.mid("", 0, *) = "" * StringUtils.mid("abc", 0, 2) = "ab" * StringUtils.mid("abc", 0, 4) = "abc" * StringUtils.mid("abc", 2, 4) = "c" * StringUtils.mid("abc", 4, 2) = "" * StringUtils.mid("abc", -2, 2) = "ab" * </pre> * * @param str the String to get the characters from, may be null * @param pos the position to start from, negative treated as zero * @param len the length of the required String * @return the middle characters, {@code null} if null String input */ public static String mid(String str, int pos, int len) { if (str == null) { return null; } if (len < 0 || pos > str.length()) { return EMPTY; } if (pos < 0) { pos = 0; } if (str.length() <= pos + len) { return str.substring(pos); } return str.substring(pos, pos + len); } // SubStringAfter/SubStringBefore //----------------------------------------------------------------------- /** * <p>Gets the substring before the first occurrence of a separator. * The separator is not returned.</p> * * <p>A {@code null} string input will return {@code null}. * An empty ("") string input will return the empty string. * A {@code null} separator will return the input string.</p> * * <p>If nothing is found, the string input is returned.</p> * * <pre> * StringUtils.substringBefore(null, *) = null * StringUtils.substringBefore("", *) = "" * StringUtils.substringBefore("abc", "a") = "" * StringUtils.substringBefore("abcba", "b") = "a" * StringUtils.substringBefore("abc", "c") = "ab" * StringUtils.substringBefore("abc", "d") = "abc" * StringUtils.substringBefore("abc", "") = "" * StringUtils.substringBefore("abc", null) = "abc" * </pre> * * @param str the String to get a substring from, may be null * @param separator the String to search for, may be null * @return the substring before the first occurrence of the separator, * {@code null} if null String input * @since 2.0 */ public static String substringBefore(String str, String separator) { if (isEmpty(str) || separator == null) { return str; } if (separator.length() == 0) { return EMPTY; } int pos = str.indexOf(separator); if (pos == INDEX_NOT_FOUND) { return str; } return str.substring(0, pos); } /** * <p>Gets the substring after the first occurrence of a separator. * The separator is not returned.</p> * * <p>A {@code null} string input will return {@code null}. * An empty ("") string input will return the empty string. * A {@code null} separator will return the empty string if the * input string is not {@code null}.</p> * * <p>If nothing is found, the empty string is returned.</p> * * <pre> * StringUtils.substringAfter(null, *) = null * StringUtils.substringAfter("", *) = "" * StringUtils.substringAfter(*, null) = "" * StringUtils.substringAfter("abc", "a") = "bc" * StringUtils.substringAfter("abcba", "b") = "cba" * StringUtils.substringAfter("abc", "c") = "" * StringUtils.substringAfter("abc", "d") = "" * StringUtils.substringAfter("abc", "") = "abc" * </pre> * * @param str the String to get a substring from, may be null * @param separator the String to search for, may be null * @return the substring after the first occurrence of the separator, * {@code null} if null String input * @since 2.0 */ public static String substringAfter(String str, String separator) { if (isEmpty(str)) { return str; } if (separator == null) { return EMPTY; } int pos = str.indexOf(separator); if (pos == INDEX_NOT_FOUND) { return EMPTY; } return str.substring(pos + separator.length()); } /** * <p>Gets the substring before the last occurrence of a separator. * The separator is not returned.</p> * * <p>A {@code null} string input will return {@code null}. * An empty ("") string input will return the empty string. * An empty or {@code null} separator will return the input string.</p> * * <p>If nothing is found, the string input is returned.</p> * * <pre> * StringUtils.substringBeforeLast(null, *) = null * StringUtils.substringBeforeLast("", *) = "" * StringUtils.substringBeforeLast("abcba", "b") = "abc" * StringUtils.substringBeforeLast("abc", "c") = "ab" * StringUtils.substringBeforeLast("a", "a") = "" * StringUtils.substringBeforeLast("a", "z") = "a" * StringUtils.substringBeforeLast("a", null) = "a" * StringUtils.substringBeforeLast("a", "") = "a" * </pre> * * @param str the String to get a substring from, may be null * @param separator the String to search for, may be null * @return the substring before the last occurrence of the separator, * {@code null} if null String input * @since 2.0 */ public static String substringBeforeLast(String str, String separator) { if (isEmpty(str) || isEmpty(separator)) { return str; } int pos = str.lastIndexOf(separator); if (pos == INDEX_NOT_FOUND) { return str; } return str.substring(0, pos); } /** * <p>Gets the substring after the last occurrence of a separator. * The separator is not returned.</p> * * <p>A {@code null} string input will return {@code null}. * An empty ("") string input will return the empty string. * An empty or {@code null} separator will return the empty string if * the input string is not {@code null}.</p> * * <p>If nothing is found, the empty string is returned.</p> * * <pre> * StringUtils.substringAfterLast(null, *) = null * StringUtils.substringAfterLast("", *) = "" * StringUtils.substringAfterLast(*, "") = "" * StringUtils.substringAfterLast(*, null) = "" * StringUtils.substringAfterLast("abc", "a") = "bc" * StringUtils.substringAfterLast("abcba", "b") = "a" * StringUtils.substringAfterLast("abc", "c") = "" * StringUtils.substringAfterLast("a", "a") = "" * StringUtils.substringAfterLast("a", "z") = "" * </pre> * * @param str the String to get a substring from, may be null * @param separator the String to search for, may be null * @return the substring after the last occurrence of the separator, * {@code null} if null String input * @since 2.0 */ public static String substringAfterLast(String str, String separator) { if (isEmpty(str)) { return str; } if (isEmpty(separator)) { return EMPTY; } int pos = str.lastIndexOf(separator); if (pos == INDEX_NOT_FOUND || pos == str.length() - separator.length()) { return EMPTY; } return str.substring(pos + separator.length()); } // Substring between //----------------------------------------------------------------------- /** * <p>Gets the String that is nested in between two instances of the * same String.</p> * * <p>A {@code null} input String returns {@code null}. * A {@code null} tag returns {@code null}.</p> * * <pre> * StringUtils.substringBetween(null, *) = null * StringUtils.substringBetween("", "") = "" * StringUtils.substringBetween("", "tag") = null * StringUtils.substringBetween("tagabctag", null) = null * StringUtils.substringBetween("tagabctag", "") = "" * StringUtils.substringBetween("tagabctag", "tag") = "abc" * </pre> * * @param str the String containing the substring, may be null * @param tag the String before and after the substring, may be null * @return the substring, {@code null} if no match * @since 2.0 */ public static String substringBetween(String str, String tag) { return substringBetween(str, tag, tag); } /** * <p>Gets the String that is nested in between two Strings. * Only the first match is returned.</p> * * <p>A {@code null} input String returns {@code null}. * A {@code null} open/close returns {@code null} (no match). * An empty ("") open and close returns an empty string.</p> * * <pre> * StringUtils.substringBetween("wx[b]yz", "[", "]") = "b" * StringUtils.substringBetween(null, *, *) = null * StringUtils.substringBetween(*, null, *) = null * StringUtils.substringBetween(*, *, null) = null * StringUtils.substringBetween("", "", "") = "" * StringUtils.substringBetween("", "", "]") = null * StringUtils.substringBetween("", "[", "]") = null * StringUtils.substringBetween("yabcz", "", "") = "" * StringUtils.substringBetween("yabcz", "y", "z") = "abc" * StringUtils.substringBetween("yabczyabcz", "y", "z") = "abc" * </pre> * * @param str the String containing the substring, may be null * @param open the String before the substring, may be null * @param close the String after the substring, may be null * @return the substring, {@code null} if no match * @since 2.0 */ public static String substringBetween(String str, String open, String close) { if (str == null || open == null || close == null) { return null; } int start = str.indexOf(open); if (start != INDEX_NOT_FOUND) { int end = str.indexOf(close, start + open.length()); if (end != INDEX_NOT_FOUND) { return str.substring(start + open.length(), end); } } return null; } // Joining //----------------------------------------------------------------------- /** * <p>Joins the elements of the provided array into a single String * containing the provided list of elements.</p> * * <p>No separator is added to the joined String. * Null objects or empty strings within the array are represented by * empty strings.</p> * * <pre> * StringUtils.join(null) = null * StringUtils.join([]) = "" * StringUtils.join([null]) = "" * StringUtils.join(["a", "b", "c"]) = "abc" * StringUtils.join([null, "", "a"]) = "a" * </pre> * * @param <T> the specific type of values to join together * @param elements the values to join together, may be null * @return the joined String, {@code null} if null array input * @since 2.0 * @since 3.0 Changed signature to use varargs */ public static <T> String join(T... elements) { return join(elements, null); } /** * <p>Joins the elements of the provided array into a single String * containing the provided list of elements.</p> * * <p>No delimiter is added before or after the list. * Null objects or empty strings within the array are represented by * empty strings.</p> * * <pre> * StringUtils.join(null, *) = null * StringUtils.join([], *) = "" * StringUtils.join([null], *) = "" * StringUtils.join(["a", "b", "c"], ';') = "a;b;c" * StringUtils.join(["a", "b", "c"], null) = "abc" * StringUtils.join([null, "", "a"], ';') = ";;a" * </pre> * * @param array the array of values to join together, may be null * @param separator the separator character to use * @return the joined String, {@code null} if null array input * @since 2.0 */ public static String join(Object[] array, char separator) { if (array == null) { return null; } return join(array, separator, 0, array.length); } /** * <p>Joins the elements of the provided array into a single String * containing the provided list of elements.</p> * * <p>No delimiter is added before or after the list. * Null objects or empty strings within the array are represented by * empty strings.</p> * * <pre> * StringUtils.join(null, *) = null * StringUtils.join([], *) = "" * StringUtils.join([null], *) = "" * StringUtils.join(["a", "b", "c"], ';') = "a;b;c" * StringUtils.join(["a", "b", "c"], null) = "abc" * StringUtils.join([null, "", "a"], ';') = ";;a" * </pre> * * @param array the array of values to join together, may be null * @param separator the separator character to use * @param startIndex the first index to start joining from. It is * an error to pass in an end index past the end of the array * @param endIndex the index to stop joining from (exclusive). It is * an error to pass in an end index past the end of the array * @return the joined String, {@code null} if null array input * @since 2.0 */ public static String join(Object[] array, char separator, int startIndex, int endIndex) { if (array == null) { return null; } int noOfItems = endIndex - startIndex; if (noOfItems <= 0) { return EMPTY; } StringBuilder buf = new StringBuilder(noOfItems * 16); for (int i = startIndex; i < endIndex; i++) { if (i > startIndex) { buf.append(separator); } if (array[i] != null) { buf.append(array[i]); } } return buf.toString(); } /** * <p>Joins the elements of the provided array into a single String * containing the provided list of elements.</p> * * <p>No delimiter is added before or after the list. * A {@code null} separator is the same as an empty String (""). * Null objects or empty strings within the array are represented by * empty strings.</p> * * <pre> * StringUtils.join(null, *) = null * StringUtils.join([], *) = "" * StringUtils.join([null], *) = "" * StringUtils.join(["a", "b", "c"], "--") = "a--b--c" * StringUtils.join(["a", "b", "c"], null) = "abc" * StringUtils.join(["a", "b", "c"], "") = "abc" * StringUtils.join([null, "", "a"], ',') = ",,a" * </pre> * * @param array the array of values to join together, may be null * @param separator the separator character to use, null treated as "" * @return the joined String, {@code null} if null array input */ public static String join(Object[] array, String separator) { if (array == null) { return null; } return join(array, separator, 0, array.length); } /** * <p>Joins the elements of the provided array into a single String * containing the provided list of elements.</p> * * <p>No delimiter is added before or after the list. * A {@code null} separator is the same as an empty String (""). * Null objects or empty strings within the array are represented by * empty strings.</p> * * <pre> * StringUtils.join(null, *) = null * StringUtils.join([], *) = "" * StringUtils.join([null], *) = "" * StringUtils.join(["a", "b", "c"], "--") = "a--b--c" * StringUtils.join(["a", "b", "c"], null) = "abc" * StringUtils.join(["a", "b", "c"], "") = "abc" * StringUtils.join([null, "", "a"], ',') = ",,a" * </pre> * * @param array the array of values to join together, may be null * @param separator the separator character to use, null treated as "" * @param startIndex the first index to start joining from. It is * an error to pass in an end index past the end of the array * @param endIndex the index to stop joining from (exclusive). It is * an error to pass in an end index past the end of the array * @return the joined String, {@code null} if null array input */ public static String join(Object[] array, String separator, int startIndex, int endIndex) { if (array == null) { return null; } if (separator == null) { separator = EMPTY; } // endIndex - startIndex > 0: Len = NofStrings *(len(firstString) + len(separator)) // (Assuming that all Strings are roughly equally long) int noOfItems = endIndex - startIndex; if (noOfItems <= 0) { return EMPTY; } StringBuilder buf = new StringBuilder(noOfItems * 16); for (int i = startIndex; i < endIndex; i++) { if (i > startIndex) { buf.append(separator); } if (array[i] != null) { buf.append(array[i]); } } return buf.toString(); } /** * <p>Joins the elements of the provided {@code Iterable} into * a single String containing the provided elements.</p> * * <p>No delimiter is added before or after the list. Null objects or empty * strings within the iteration are represented by empty strings.</p> * * <p>See the examples here: {@link #join(Object[],char)}. </p> * * @param iterable the {@code Iterable} providing the values to join together, may be null * @param separator the separator character to use * @return the joined String, {@code null} if null iterator input * @since 2.3 */ public static String join(Iterable<?> iterable, char separator) { if (iterable == null) { return null; } return join(iterable.iterator(), separator); } /** * <p>Joins the elements of the provided {@code Iterable} into * a single String containing the provided elements.</p> * * <p>No delimiter is added before or after the list. * A {@code null} separator is the same as an empty String ("").</p> * * <p>See the examples here: {@link #join(Object[],String)}. </p> * * @param iterable the {@code Iterable} providing the values to join together, may be null * @param separator the separator character to use, null treated as "" * @return the joined String, {@code null} if null iterator input * @since 2.3 */ public static String join(Iterable<?> iterable, String separator) { if (iterable == null) { return null; } return join(iterable.iterator(), separator); } // Delete //----------------------------------------------------------------------- /** * <p>Deletes all whitespaces from a String as defined by * {@link Character#isWhitespace(char)}.</p> * * <pre> * StringUtils.deleteWhitespace(null) = null * StringUtils.deleteWhitespace("") = "" * StringUtils.deleteWhitespace("abc") = "abc" * StringUtils.deleteWhitespace(" ab c ") = "abc" * </pre> * * @param str the String to delete whitespace from, may be null * @return the String without whitespaces, {@code null} if null String input */ public static String deleteWhitespace(String str) { if (isEmpty(str)) { return str; } int sz = str.length(); char[] chs = new char[sz]; int count = 0; for (int i = 0; i < sz; i++) { if (!Character.isWhitespace(str.charAt(i))) { chs[count++] = str.charAt(i); } } if (count == sz) { return str; } return new String(chs, 0, count); } // Remove //----------------------------------------------------------------------- /** * <p>Removes a substring only if it is at the beginning of a source string, * otherwise returns the source string.</p> * * <p>A {@code null} source string will return {@code null}. * An empty ("") source string will return the empty string. * A {@code null} search string will return the source string.</p> * * <pre> * StringUtils.removeStart(null, *) = null * StringUtils.removeStart("", *) = "" * StringUtils.removeStart(*, null) = * * StringUtils.removeStart("www.domain.com", "www.") = "domain.com" * StringUtils.removeStart("domain.com", "www.") = "domain.com" * StringUtils.removeStart("www.domain.com", "domain") = "www.domain.com" * StringUtils.removeStart("abc", "") = "abc" * </pre> * * @param str the source String to search, may be null * @param remove the String to search for and remove, may be null * @return the substring with the string removed if found, * {@code null} if null String input * @since 2.1 */ public static String removeStart(String str, String remove) { if (isEmpty(str) || isEmpty(remove)) { return str; } if (str.startsWith(remove)){ return str.substring(remove.length()); } return str; } /** * <p>Removes a substring only if it is at the end of a source string, * otherwise returns the source string.</p> * * <p>A {@code null} source string will return {@code null}. * An empty ("") source string will return the empty string. * A {@code null} search string will return the source string.</p> * * <pre> * StringUtils.removeEnd(null, *) = null * StringUtils.removeEnd("", *) = "" * StringUtils.removeEnd(*, null) = * * StringUtils.removeEnd("www.domain.com", ".com.") = "www.domain.com" * StringUtils.removeEnd("www.domain.com", ".com") = "www.domain" * StringUtils.removeEnd("www.domain.com", "domain") = "www.domain.com" * StringUtils.removeEnd("abc", "") = "abc" * </pre> * * @param str the source String to search, may be null * @param remove the String to search for and remove, may be null * @return the substring with the string removed if found, * {@code null} if null String input * @since 2.1 */ public static String removeEnd(String str, String remove) { if (isEmpty(str) || isEmpty(remove)) { return str; } if (str.endsWith(remove)) { return str.substring(0, str.length() - remove.length()); } return str; } /** * <p>Removes all occurrences of a substring from within the source string.</p> * * <p>A {@code null} source string will return {@code null}. * An empty ("") source string will return the empty string. * A {@code null} remove string will return the source string. * An empty ("") remove string will return the source string.</p> * * <pre> * StringUtils.remove(null, *) = null * StringUtils.remove("", *) = "" * StringUtils.remove(*, null) = * * StringUtils.remove(*, "") = * * StringUtils.remove("queued", "ue") = "qd" * StringUtils.remove("queued", "zz") = "queued" * </pre> * * @param str the source String to search, may be null * @param remove the String to search for and remove, may be null * @return the substring with the string removed if found, * {@code null} if null String input * @since 2.1 */ public static String remove(String str, String remove) { if (isEmpty(str) || isEmpty(remove)) { return str; } return replace(str, remove, EMPTY, -1); } /** * <p>Removes all occurrences of a character from within the source string.</p> * * <p>A {@code null} source string will return {@code null}. * An empty ("") source string will return the empty string.</p> * * <pre> * StringUtils.remove(null, *) = null * StringUtils.remove("", *) = "" * StringUtils.remove("queued", 'u') = "qeed" * StringUtils.remove("queued", 'z') = "queued" * </pre> * * @param str the source String to search, may be null * @param remove the char to search for and remove, may be null * @return the substring with the char removed if found, * {@code null} if null String input * @since 2.1 */ public static String remove(String str, char remove) { if (isEmpty(str) || str.indexOf(remove) == INDEX_NOT_FOUND) { return str; } char[] chars = str.toCharArray(); int pos = 0; for (int i = 0; i < chars.length; i++) { if (chars[i] != remove) { chars[pos++] = chars[i]; } } return new String(chars, 0, pos); } // Replacing //----------------------------------------------------------------------- /** * <p>Replaces a String with another String inside a larger String, once.</p> * * <p>A {@code null} reference passed to this method is a no-op.</p> * * <pre> * StringUtils.replaceOnce(null, *, *) = null * StringUtils.replaceOnce("", *, *) = "" * StringUtils.replaceOnce("any", null, *) = "any" * StringUtils.replaceOnce("any", *, null) = "any" * StringUtils.replaceOnce("any", "", *) = "any" * StringUtils.replaceOnce("aba", "a", null) = "aba" * StringUtils.replaceOnce("aba", "a", "") = "ba" * StringUtils.replaceOnce("aba", "a", "z") = "zba" * </pre> * * @see #replace(String text, String searchString, String replacement, int max) * @param text text to search and replace in, may be null * @param searchString the String to search for, may be null * @param replacement the String to replace with, may be null * @return the text with any replacements processed, * {@code null} if null String input */ public static String replaceOnce(String text, String searchString, String replacement) { return replace(text, searchString, replacement, 1); } /** * <p>Replaces all occurrences of a String within another String.</p> * * <p>A {@code null} reference passed to this method is a no-op.</p> * * <pre> * StringUtils.replace(null, *, *) = null * StringUtils.replace("", *, *) = "" * StringUtils.replace("any", null, *) = "any" * StringUtils.replace("any", *, null) = "any" * StringUtils.replace("any", "", *) = "any" * StringUtils.replace("aba", "a", null) = "aba" * StringUtils.replace("aba", "a", "") = "b" * StringUtils.replace("aba", "a", "z") = "zbz" * </pre> * * @see #replace(String text, String searchString, String replacement, int max) * @param text text to search and replace in, may be null * @param searchString the String to search for, may be null * @param replacement the String to replace it with, may be null * @return the text with any replacements processed, * {@code null} if null String input */ public static String replace(String text, String searchString, String replacement) { return replace(text, searchString, replacement, -1); } /** * <p>Replaces a String with another String inside a larger String, * for the first {@code max} values of the search String.</p> * * <p>A {@code null} reference passed to this method is a no-op.</p> * * <pre> * StringUtils.replace(null, *, *, *) = null * StringUtils.replace("", *, *, *) = "" * StringUtils.replace("any", null, *, *) = "any" * StringUtils.replace("any", *, null, *) = "any" * StringUtils.replace("any", "", *, *) = "any" * StringUtils.replace("any", *, *, 0) = "any" * StringUtils.replace("abaa", "a", null, -1) = "abaa" * StringUtils.replace("abaa", "a", "", -1) = "b" * StringUtils.replace("abaa", "a", "z", 0) = "abaa" * StringUtils.replace("abaa", "a", "z", 1) = "zbaa" * StringUtils.replace("abaa", "a", "z", 2) = "zbza" * StringUtils.replace("abaa", "a", "z", -1) = "zbzz" * </pre> * * @param text text to search and replace in, may be null * @param searchString the String to search for, may be null * @param replacement the String to replace it with, may be null * @param max maximum number of values to replace, or {@code -1} if no maximum * @return the text with any replacements processed, * {@code null} if null String input */ public static String replace(String text, String searchString, String replacement, int max) { if (isEmpty(text) || isEmpty(searchString) || replacement == null || max == 0) { return text; } int start = 0; int end = text.indexOf(searchString, start); if (end == INDEX_NOT_FOUND) { return text; } int replLength = searchString.length(); int increase = replacement.length() - replLength; increase = increase < 0 ? 0 : increase; increase *= max < 0 ? 16 : max > 64 ? 64 : max; StringBuilder buf = new StringBuilder(text.length() + increase); while (end != INDEX_NOT_FOUND) { buf.append(text.substring(start, end)).append(replacement); start = end + replLength; if (--max == 0) { break; } end = text.indexOf(searchString, start); } buf.append(text.substring(start)); return buf.toString(); } /** * <p> * Replaces all occurrences of Strings within another String. * </p> * * <p> * A {@code null} reference passed to this method is a no-op, or if * any "search string" or "string to replace" is null, that replace will be * ignored. This will not repeat. For repeating replaces, call the * overloaded method. * </p> * * <pre> * StringUtils.replaceEach(null, *, *) = null * StringUtils.replaceEach("", *, *) = "" * StringUtils.replaceEach("aba", null, null) = "aba" * StringUtils.replaceEach("aba", new String[0], null) = "aba" * StringUtils.replaceEach("aba", null, new String[0]) = "aba" * StringUtils.replaceEach("aba", new String[]{"a"}, null) = "aba" * StringUtils.replaceEach("aba", new String[]{"a"}, new String[]{""}) = "b" * StringUtils.replaceEach("aba", new String[]{null}, new String[]{"a"}) = "aba" * StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"w", "t"}) = "wcte" * (example of how it does not repeat) * StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "t"}) = "dcte" * </pre> * * @param text * text to search and replace in, no-op if null * @param searchList * the Strings to search for, no-op if null * @param replacementList * the Strings to replace them with, no-op if null * @return the text with any replacements processed, {@code null} if * null String input * @throws IllegalArgumentException * if the lengths of the arrays are not the same (null is ok, * and/or size 0) * @since 2.4 */ public static String replaceEach(String text, String[] searchList, String[] replacementList) { return replaceEach(text, searchList, replacementList, false, 0); } /** * <p> * Replaces all occurrences of Strings within another String. * </p> * * <p> * A {@code null} reference passed to this method is a no-op, or if * any "search string" or "string to replace" is null, that replace will be * ignored. * </p> * * <pre> * StringUtils.replaceEach(null, *, *, *) = null * StringUtils.replaceEach("", *, *, *) = "" * StringUtils.replaceEach("aba", null, null, *) = "aba" * StringUtils.replaceEach("aba", new String[0], null, *) = "aba" * StringUtils.replaceEach("aba", null, new String[0], *) = "aba" * StringUtils.replaceEach("aba", new String[]{"a"}, null, *) = "aba" * StringUtils.replaceEach("aba", new String[]{"a"}, new String[]{""}, *) = "b" * StringUtils.replaceEach("aba", new String[]{null}, new String[]{"a"}, *) = "aba" * StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"w", "t"}, *) = "wcte" * (example of how it repeats) * StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "t"}, false) = "dcte" * StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "t"}, true) = "tcte" * StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "ab"}, true) = IllegalStateException * StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "ab"}, false) = "dcabe" * </pre> * * @param text * text to search and replace in, no-op if null * @param searchList * the Strings to search for, no-op if null * @param replacementList * the Strings to replace them with, no-op if null * @return the text with any replacements processed, {@code null} if * null String input * @throws IllegalStateException * if the search is repeating and there is an endless loop due * to outputs of one being inputs to another * @throws IllegalArgumentException * if the lengths of the arrays are not the same (null is ok, * and/or size 0) * @since 2.4 */ public static String replaceEachRepeatedly(String text, String[] searchList, String[] replacementList) { // timeToLive should be 0 if not used or nothing to replace, else it's // the length of the replace array int timeToLive = searchList == null ? 0 : searchList.length; return replaceEach(text, searchList, replacementList, true, timeToLive); } /** * <p> * Replaces all occurrences of Strings within another String. * </p> * * <p> * A {@code null} reference passed to this method is a no-op, or if * any "search string" or "string to replace" is null, that replace will be * ignored. * </p> * * <pre> * StringUtils.replaceEach(null, *, *, *) = null * StringUtils.replaceEach("", *, *, *) = "" * StringUtils.replaceEach("aba", null, null, *) = "aba" * StringUtils.replaceEach("aba", new String[0], null, *) = "aba" * StringUtils.replaceEach("aba", null, new String[0], *) = "aba" * StringUtils.replaceEach("aba", new String[]{"a"}, null, *) = "aba" * StringUtils.replaceEach("aba", new String[]{"a"}, new String[]{""}, *) = "b" * StringUtils.replaceEach("aba", new String[]{null}, new String[]{"a"}, *) = "aba" * StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"w", "t"}, *) = "wcte" * (example of how it repeats) * StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "t"}, false) = "dcte" * StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "t"}, true) = "tcte" * StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "ab"}, *) = IllegalStateException * </pre> * * @param text * text to search and replace in, no-op if null * @param searchList * the Strings to search for, no-op if null * @param replacementList * the Strings to replace them with, no-op if null * @param repeat if true, then replace repeatedly * until there are no more possible replacements or timeToLive < 0 * @param timeToLive * if less than 0 then there is a circular reference and endless * loop * @return the text with any replacements processed, {@code null} if * null String input * @throws IllegalStateException * if the search is repeating and there is an endless loop due * to outputs of one being inputs to another * @throws IllegalArgumentException * if the lengths of the arrays are not the same (null is ok, * and/or size 0) * @since 2.4 */ private static String replaceEach( String text, String[] searchList, String[] replacementList, boolean repeat, int timeToLive) { // mchyzer Performance note: This creates very few new objects (one major goal) // let me know if there are performance requests, we can create a harness to measure if (text == null || text.length() == 0 || searchList == null || searchList.length == 0 || replacementList == null || replacementList.length == 0) { return text; } // if recursing, this shouldn't be less than 0 if (timeToLive < 0) { throw new IllegalStateException("Aborting to protect against StackOverflowError - " + "output of one loop is the input of another"); } int searchLength = searchList.length; int replacementLength = replacementList.length; // make sure lengths are ok, these need to be equal if (searchLength != replacementLength) { throw new IllegalArgumentException("Search and Replace array lengths don't match: " + searchLength + " vs " + replacementLength); } // keep track of which still have matches boolean[] noMoreMatchesForReplIndex = new boolean[searchLength]; // index on index that the match was found int textIndex = -1; int replaceIndex = -1; int tempIndex = -1; // index of replace array that will replace the search string found // NOTE: logic duplicated below START for (int i = 0; i < searchLength; i++) { if (noMoreMatchesForReplIndex[i] || searchList[i] == null || searchList[i].length() == 0 || replacementList[i] == null) { continue; } tempIndex = text.indexOf(searchList[i]); // see if we need to keep searching for this if (tempIndex == -1) { noMoreMatchesForReplIndex[i] = true; } else { if (textIndex == -1 || tempIndex < textIndex) { textIndex = tempIndex; replaceIndex = i; } } } // NOTE: logic mostly below END // no search strings found, we are done if (textIndex == -1) { return text; } int start = 0; // get a good guess on the size of the result buffer so it doesn't have to double if it goes over a bit int increase = 0; // count the replacement text elements that are larger than their corresponding text being replaced for (int i = 0; i < searchList.length; i++) { if (searchList[i] == null || replacementList[i] == null) { continue; } int greater = replacementList[i].length() - searchList[i].length(); if (greater > 0) { increase += 3 * greater; // assume 3 matches } } // have upper-bound at 20% increase, then let Java take over increase = Math.min(increase, text.length() / 5); StringBuilder buf = new StringBuilder(text.length() + increase); while (textIndex != -1) { for (int i = start; i < textIndex; i++) { buf.append(text.charAt(i)); } buf.append(replacementList[replaceIndex]); start = textIndex + searchList[replaceIndex].length(); textIndex = -1; replaceIndex = -1; tempIndex = -1; // find the next earliest match // NOTE: logic mostly duplicated above START for (int i = 0; i < searchLength; i++) { if (noMoreMatchesForReplIndex[i] || searchList[i] == null || searchList[i].length() == 0 || replacementList[i] == null) { continue; } tempIndex = text.indexOf(searchList[i], start); // see if we need to keep searching for this if (tempIndex == -1) { noMoreMatchesForReplIndex[i] = true; } else { if (textIndex == -1 || tempIndex < textIndex) { textIndex = tempIndex; replaceIndex = i; } } } // NOTE: logic duplicated above END } int textLength = text.length(); for (int i = start; i < textLength; i++) { buf.append(text.charAt(i)); } String result = buf.toString(); if (!repeat) { return result; } return replaceEach(result, searchList, replacementList, repeat, timeToLive - 1); } // Replace, character based //----------------------------------------------------------------------- /** * <p>Replaces all occurrences of a character in a String with another. * This is a null-safe version of {@link String#replace(char, char)}.</p> * * <p>A {@code null} string input returns {@code null}. * An empty ("") string input returns an empty string.</p> * * <pre> * StringUtils.replaceChars(null, *, *) = null * StringUtils.replaceChars("", *, *) = "" * StringUtils.replaceChars("abcba", 'b', 'y') = "aycya" * StringUtils.replaceChars("abcba", 'z', 'y') = "abcba" * </pre> * * @param str String to replace characters in, may be null * @param searchChar the character to search for, may be null * @param replaceChar the character to replace, may be null * @return modified String, {@code null} if null string input * @since 2.0 */ public static String replaceChars(String str, char searchChar, char replaceChar) { if (str == null) { return null; } return str.replace(searchChar, replaceChar); } /** * <p>Replaces multiple characters in a String in one go. * This method can also be used to delete characters.</p> * * <p>For example:<br /> * <code>replaceChars("hello", "ho", "jy") = jelly</code>.</p> * * <p>A {@code null} string input returns {@code null}. * An empty ("") string input returns an empty string. * A null or empty set of search characters returns the input string.</p> * * <p>The length of the search characters should normally equal the length * of the replace characters. * If the search characters is longer, then the extra search characters * are deleted. * If the search characters is shorter, then the extra replace characters * are ignored.</p> * * <pre> * StringUtils.replaceChars(null, *, *) = null * StringUtils.replaceChars("", *, *) = "" * StringUtils.replaceChars("abc", null, *) = "abc" * StringUtils.replaceChars("abc", "", *) = "abc" * StringUtils.replaceChars("abc", "b", null) = "ac" * StringUtils.replaceChars("abc", "b", "") = "ac" * StringUtils.replaceChars("abcba", "bc", "yz") = "ayzya" * StringUtils.replaceChars("abcba", "bc", "y") = "ayya" * StringUtils.replaceChars("abcba", "bc", "yzx") = "ayzya" * </pre> * * @param str String to replace characters in, may be null * @param searchChars a set of characters to search for, may be null * @param replaceChars a set of characters to replace, may be null * @return modified String, {@code null} if null string input * @since 2.0 */ public static String replaceChars(String str, String searchChars, String replaceChars) { if (isEmpty(str) || isEmpty(searchChars)) { return str; } if (replaceChars == null) { replaceChars = EMPTY; } boolean modified = false; int replaceCharsLength = replaceChars.length(); int strLength = str.length(); StringBuilder buf = new StringBuilder(strLength); for (int i = 0; i < strLength; i++) { char ch = str.charAt(i); int index = searchChars.indexOf(ch); if (index >= 0) { modified = true; if (index < replaceCharsLength) { buf.append(replaceChars.charAt(index)); } } else { buf.append(ch); } } if (modified) { return buf.toString(); } return str; } // Overlay //----------------------------------------------------------------------- /** * <p>Overlays part of a String with another String.</p> * * <p>A {@code null} string input returns {@code null}. * A negative index is treated as zero. * An index greater than the string length is treated as the string length. * The start index is always the smaller of the two indices.</p> * * <pre> * StringUtils.overlay(null, *, *, *) = null * StringUtils.overlay("", "abc", 0, 0) = "abc" * StringUtils.overlay("abcdef", null, 2, 4) = "abef" * StringUtils.overlay("abcdef", "", 2, 4) = "abef" * StringUtils.overlay("abcdef", "", 4, 2) = "abef" * StringUtils.overlay("abcdef", "zzzz", 2, 4) = "abzzzzef" * StringUtils.overlay("abcdef", "zzzz", 4, 2) = "abzzzzef" * StringUtils.overlay("abcdef", "zzzz", -1, 4) = "zzzzef" * StringUtils.overlay("abcdef", "zzzz", 2, 8) = "abzzzz" * StringUtils.overlay("abcdef", "zzzz", -2, -3) = "zzzzabcdef" * StringUtils.overlay("abcdef", "zzzz", 8, 10) = "abcdefzzzz" * </pre> * * @param str the String to do overlaying in, may be null * @param overlay the String to overlay, may be null * @param start the position to start overlaying at * @param end the position to stop overlaying before * @return overlayed String, {@code null} if null String input * @since 2.0 */ public static String overlay(String str, String overlay, int start, int end) { if (str == null) { return null; } if (overlay == null) { overlay = EMPTY; } int len = str.length(); if (start < 0) { start = 0; } if (start > len) { start = len; } if (end < 0) { end = 0; } if (end > len) { end = len; } if (start > end) { int temp = start; start = end; end = temp; } return new StringBuilder(len + start - end + overlay.length() + 1) .append(str.substring(0, start)) .append(overlay) .append(str.substring(end)) .toString(); } /** * <p>Removes {@code separator} from the end of * {@code str} if it's there, otherwise leave it alone.</p> * * <p>NOTE: This method changed in version 2.0. * It now more closely matches Perl chomp. * For the previous behavior, use {@link #substringBeforeLast(String, String)}. * This method uses {@link String#endsWith(String)}.</p> * * <pre> * StringUtils.chomp(null, *) = null * StringUtils.chomp("", *) = "" * StringUtils.chomp("foobar", "bar") = "foo" * StringUtils.chomp("foobar", "baz") = "foobar" * StringUtils.chomp("foo", "foo") = "" * StringUtils.chomp("foo ", "foo") = "foo " * StringUtils.chomp(" foo", "foo") = " " * StringUtils.chomp("foo", "foooo") = "foo" * StringUtils.chomp("foo", "") = "foo" * StringUtils.chomp("foo", null) = "foo" * </pre> * * @param str the String to chomp from, may be null * @param separator separator String, may be null * @return String without trailing separator, {@code null} if null String input * @deprecated This feature will be removed in Lang 4.0, use {@link StringUtils#removeEnd(String, String)} instead */ @Deprecated public static String chomp(String str, String separator) { return removeEnd(str,separator); } // Padding //----------------------------------------------------------------------- /** * <p>Repeat a String {@code repeat} times to form a * new String.</p> * * <pre> * StringUtils.repeat(null, 2) = null * StringUtils.repeat("", 0) = "" * StringUtils.repeat("", 2) = "" * StringUtils.repeat("a", 3) = "aaa" * StringUtils.repeat("ab", 2) = "abab" * StringUtils.repeat("a", -2) = "" * </pre> * * @param str the String to repeat, may be null * @param repeat number of times to repeat str, negative treated as zero * @return a new String consisting of the original String repeated, * {@code null} if null String input */ public static String repeat(String str, int repeat) { // Performance tuned for 2.0 (JDK1.4) if (str == null) { return null; } if (repeat <= 0) { return EMPTY; } int inputLength = str.length(); if (repeat == 1 || inputLength == 0) { return str; } if (inputLength == 1 && repeat <= PAD_LIMIT) { return repeat(str.charAt(0), repeat); } int outputLength = inputLength * repeat; switch (inputLength) { case 1 : return repeat(str.charAt(0), repeat); case 2 : char ch0 = str.charAt(0); char ch1 = str.charAt(1); char[] output2 = new char[outputLength]; for (int i = repeat * 2 - 2; i >= 0; i--, i--) { output2[i] = ch0; output2[i + 1] = ch1; } return new String(output2); default : StringBuilder buf = new StringBuilder(outputLength); for (int i = 0; i < repeat; i++) { buf.append(str); } return buf.toString(); } } /** * <p>Repeat a String {@code repeat} times to form a * new String, with a String separator injected each time. </p> * * <pre> * StringUtils.repeat(null, null, 2) = null * StringUtils.repeat(null, "x", 2) = null * StringUtils.repeat("", null, 0) = "" * StringUtils.repeat("", "", 2) = "" * StringUtils.repeat("", "x", 3) = "xxx" * StringUtils.repeat("?", ", ", 3) = "?, ?, ?" * </pre> * * @param str the String to repeat, may be null * @param separator the String to inject, may be null * @param repeat number of times to repeat str, negative treated as zero * @return a new String consisting of the original String repeated, * {@code null} if null String input * @since 2.5 */ public static String repeat(String str, String separator, int repeat) { if(str == null || separator == null) { return repeat(str, repeat); } else { // given that repeat(String, int) is quite optimized, better to rely on it than try and splice this into it String result = repeat(str + separator, repeat); return removeEnd(result, separator); } } /** * <p>Returns padding using the specified delimiter repeated * to a given length.</p> * * <pre> * StringUtils.repeat(0, 'e') = "" * StringUtils.repeat(3, 'e') = "eee" * StringUtils.repeat(-2, 'e') = "" * </pre> * * <p>Note: this method doesn't not support padding with * <a href="http://www.unicode.org/glossary/#supplementary_character">Unicode Supplementary Characters</a> * as they require a pair of {@code char}s to be represented. * If you are needing to support full I18N of your applications * consider using {@link #repeat(String, int)} instead. * </p> * * @param ch character to repeat * @param repeat number of times to repeat char, negative treated as zero * @return String with repeated character * @see #repeat(String, int) */ public static String repeat(char ch, int repeat) { char[] buf = new char[repeat]; for (int i = repeat - 1; i >= 0; i--) { buf[i] = ch; } return new String(buf); } /** * <p>Right pad a String with spaces (' ').</p> * * <p>The String is padded to the size of {@code size}.</p> * * <pre> * StringUtils.rightPad(null, *) = null * StringUtils.rightPad("", 3) = " " * StringUtils.rightPad("bat", 3) = "bat" * StringUtils.rightPad("bat", 5) = "bat " * StringUtils.rightPad("bat", 1) = "bat" * StringUtils.rightPad("bat", -1) = "bat" * </pre> * * @param str the String to pad out, may be null * @param size the size to pad to * @return right padded String or original String if no padding is necessary, * {@code null} if null String input */ public static String rightPad(String str, int size) { return rightPad(str, size, ' '); } /** * <p>Right pad a String with a specified character.</p> * * <p>The String is padded to the size of {@code size}.</p> * * <pre> * StringUtils.rightPad(null, *, *) = null * StringUtils.rightPad("", 3, 'z') = "zzz" * StringUtils.rightPad("bat", 3, 'z') = "bat" * StringUtils.rightPad("bat", 5, 'z') = "batzz" * StringUtils.rightPad("bat", 1, 'z') = "bat" * StringUtils.rightPad("bat", -1, 'z') = "bat" * </pre> * * @param str the String to pad out, may be null * @param size the size to pad to * @param padChar the character to pad with * @return right padded String or original String if no padding is necessary, * {@code null} if null String input * @since 2.0 */ public static String rightPad(String str, int size, char padChar) { if (str == null) { return null; } int pads = size - str.length(); if (pads <= 0) { return str; // returns original String when possible } if (pads > PAD_LIMIT) { return rightPad(str, size, String.valueOf(padChar)); } return str.concat(repeat(padChar, pads)); } /** * <p>Right pad a String with a specified String.</p> * * <p>The String is padded to the size of {@code size}.</p> * * <pre> * StringUtils.rightPad(null, *, *) = null * StringUtils.rightPad("", 3, "z") = "zzz" * StringUtils.rightPad("bat", 3, "yz") = "bat" * StringUtils.rightPad("bat", 5, "yz") = "batyz" * StringUtils.rightPad("bat", 8, "yz") = "batyzyzy" * StringUtils.rightPad("bat", 1, "yz") = "bat" * StringUtils.rightPad("bat", -1, "yz") = "bat" * StringUtils.rightPad("bat", 5, null) = "bat " * StringUtils.rightPad("bat", 5, "") = "bat " * </pre> * * @param str the String to pad out, may be null * @param size the size to pad to * @param padStr the String to pad with, null or empty treated as single space * @return right padded String or original String if no padding is necessary, * {@code null} if null String input */ public static String rightPad(String str, int size, String padStr) { if (str == null) { return null; } if (isEmpty(padStr)) { padStr = " "; } int padLen = padStr.length(); int strLen = str.length(); int pads = size - strLen; if (pads <= 0) { return str; // returns original String when possible } if (padLen == 1 && pads <= PAD_LIMIT) { return rightPad(str, size, padStr.charAt(0)); } if (pads == padLen) { return str.concat(padStr); } else if (pads < padLen) { return str.concat(padStr.substring(0, pads)); } else { char[] padding = new char[pads]; char[] padChars = padStr.toCharArray(); for (int i = 0; i < pads; i++) { padding[i] = padChars[i % padLen]; } return str.concat(new String(padding)); } } /** * <p>Left pad a String with spaces (' ').</p> * * <p>The String is padded to the size of {@code size}.</p> * * <pre> * StringUtils.leftPad(null, *) = null * StringUtils.leftPad("", 3) = " " * StringUtils.leftPad("bat", 3) = "bat" * StringUtils.leftPad("bat", 5) = " bat" * StringUtils.leftPad("bat", 1) = "bat" * StringUtils.leftPad("bat", -1) = "bat" * </pre> * * @param str the String to pad out, may be null * @param size the size to pad to * @return left padded String or original String if no padding is necessary, * {@code null} if null String input */ public static String leftPad(String str, int size) { return leftPad(str, size, ' '); } /** * <p>Left pad a String with a specified character.</p> * * <p>Pad to a size of {@code size}.</p> * * <pre> * StringUtils.leftPad(null, *, *) = null * StringUtils.leftPad("", 3, 'z') = "zzz" * StringUtils.leftPad("bat", 3, 'z') = "bat" * StringUtils.leftPad("bat", 5, 'z') = "zzbat" * StringUtils.leftPad("bat", 1, 'z') = "bat" * StringUtils.leftPad("bat", -1, 'z') = "bat" * </pre> * * @param str the String to pad out, may be null * @param size the size to pad to * @param padChar the character to pad with * @return left padded String or original String if no padding is necessary, * {@code null} if null String input * @since 2.0 */ public static String leftPad(String str, int size, char padChar) { if (str == null) { return null; } int pads = size - str.length(); if (pads <= 0) { return str; // returns original String when possible } if (pads > PAD_LIMIT) { return leftPad(str, size, String.valueOf(padChar)); } return repeat(padChar, pads).concat(str); } /** * <p>Left pad a String with a specified String.</p> * * <p>Pad to a size of {@code size}.</p> * * <pre> * StringUtils.leftPad(null, *, *) = null * StringUtils.leftPad("", 3, "z") = "zzz" * StringUtils.leftPad("bat", 3, "yz") = "bat" * StringUtils.leftPad("bat", 5, "yz") = "yzbat" * StringUtils.leftPad("bat", 8, "yz") = "yzyzybat" * StringUtils.leftPad("bat", 1, "yz") = "bat" * StringUtils.leftPad("bat", -1, "yz") = "bat" * StringUtils.leftPad("bat", 5, null) = " bat" * StringUtils.leftPad("bat", 5, "") = " bat" * </pre> * * @param str the String to pad out, may be null * @param size the size to pad to * @param padStr the String to pad with, null or empty treated as single space * @return left padded String or original String if no padding is necessary, * {@code null} if null String input */ public static String leftPad(String str, int size, String padStr) { if (str == null) { return null; } if (isEmpty(padStr)) { padStr = " "; } int padLen = padStr.length(); int strLen = str.length(); int pads = size - strLen; if (pads <= 0) { return str; // returns original String when possible } if (padLen == 1 && pads <= PAD_LIMIT) { return leftPad(str, size, padStr.charAt(0)); } if (pads == padLen) { return padStr.concat(str); } else if (pads < padLen) { return padStr.substring(0, pads).concat(str); } else { char[] padding = new char[pads]; char[] padChars = padStr.toCharArray(); for (int i = 0; i < pads; i++) { padding[i] = padChars[i % padLen]; } return new String(padding).concat(str); } } /** * Gets a CharSequence length or {@code 0} if the CharSequence is * {@code null}. * * @param cs * a CharSequence or {@code null} * @return CharSequence length or {@code 0} if the CharSequence is * {@code null}. * @since 2.4 * @since 3.0 Changed signature from length(String) to length(CharSequence) */ public static int length(CharSequence cs) { return cs == null ? 0 : cs.length(); } // Centering //----------------------------------------------------------------------- /** * <p>Centers a String in a larger String of size {@code size} * using the space character (' ').<p> * * <p>If the size is less than the String length, the String is returned. * A {@code null} String returns {@code null}. * A negative size is treated as zero.</p> * * <p>Equivalent to {@code center(str, size, " ")}.</p> * * <pre> * StringUtils.center(null, *) = null * StringUtils.center("", 4) = " " * StringUtils.center("ab", -1) = "ab" * StringUtils.center("ab", 4) = " ab " * StringUtils.center("abcd", 2) = "abcd" * StringUtils.center("a", 4) = " a " * </pre> * * @param str the String to center, may be null * @param size the int size of new String, negative treated as zero * @return centered String, {@code null} if null String input */ public static String center(String str, int size) { return center(str, size, ' '); } /** * <p>Centers a String in a larger String of size {@code size}. * Uses a supplied character as the value to pad the String with.</p> * * <p>If the size is less than the String length, the String is returned. * A {@code null} String returns {@code null}. * A negative size is treated as zero.</p> * * <pre> * StringUtils.center(null, *, *) = null * StringUtils.center("", 4, ' ') = " " * StringUtils.center("ab", -1, ' ') = "ab" * StringUtils.center("ab", 4, ' ') = " ab" * StringUtils.center("abcd", 2, ' ') = "abcd" * StringUtils.center("a", 4, ' ') = " a " * StringUtils.center("a", 4, 'y') = "yayy" * </pre> * * @param str the String to center, may be null * @param size the int size of new String, negative treated as zero * @param padChar the character to pad the new String with * @return centered String, {@code null} if null String input * @since 2.0 */ public static String center(String str, int size, char padChar) { if (str == null || size <= 0) { return str; } int strLen = str.length(); int pads = size - strLen; if (pads <= 0) { return str; } str = leftPad(str, strLen + pads / 2, padChar); str = rightPad(str, size, padChar); return str; } /** * <p>Centers a String in a larger String of size {@code size}. * Uses a supplied String as the value to pad the String with.</p> * * <p>If the size is less than the String length, the String is returned. * A {@code null} String returns {@code null}. * A negative size is treated as zero.</p> * * <pre> * StringUtils.center(null, *, *) = null * StringUtils.center("", 4, " ") = " " * StringUtils.center("ab", -1, " ") = "ab" * StringUtils.center("ab", 4, " ") = " ab" * StringUtils.center("abcd", 2, " ") = "abcd" * StringUtils.center("a", 4, " ") = " a " * StringUtils.center("a", 4, "yz") = "yayz" * StringUtils.center("abc", 7, null) = " abc " * StringUtils.center("abc", 7, "") = " abc " * </pre> * * @param str the String to center, may be null * @param size the int size of new String, negative treated as zero * @param padStr the String to pad the new String with, must not be null or empty * @return centered String, {@code null} if null String input * @throws IllegalArgumentException if padStr is {@code null} or empty */ public static String center(String str, int size, String padStr) { if (str == null || size <= 0) { return str; } if (isEmpty(padStr)) { padStr = " "; } int strLen = str.length(); int pads = size - strLen; if (pads <= 0) { return str; } str = leftPad(str, strLen + pads / 2, padStr); str = rightPad(str, size, padStr); return str; } // Case conversion //----------------------------------------------------------------------- /** * <p>Converts a String to upper case as per {@link String#toUpperCase(Locale)}.</p> * * <p>A {@code null} input String returns {@code null}.</p> * * <pre> * StringUtils.upperCase(null, Locale.ENGLISH) = null * StringUtils.upperCase("", Locale.ENGLISH) = "" * StringUtils.upperCase("aBc", Locale.ENGLISH) = "ABC" * </pre> * * @param str the String to upper case, may be null * @param locale the locale that defines the case transformation rules, must not be null * @return the upper cased String, {@code null} if null String input * @since 2.5 */ public static String upperCase(String str, Locale locale) { if (str == null) { return null; } return str.toUpperCase(locale); } /** * <p>Converts a String to lower case as per {@link String#toLowerCase(Locale)}.</p> * * <p>A {@code null} input String returns {@code null}.</p> * * <pre> * StringUtils.lowerCase(null, Locale.ENGLISH) = null * StringUtils.lowerCase("", Locale.ENGLISH) = "" * StringUtils.lowerCase("aBc", Locale.ENGLISH) = "abc" * </pre> * * @param str the String to lower case, may be null * @param locale the locale that defines the case transformation rules, must not be null * @return the lower cased String, {@code null} if null String input * @since 2.5 */ public static String lowerCase(String str, Locale locale) { if (str == null) { return null; } return str.toLowerCase(locale); } /** * <p>Capitalizes a String changing the first letter to title case as * per {@link Character#toTitleCase(char)}. No other letters are changed.</p> * * <p>For a word based algorithm, see {@link org.apache.commons.lang3.text.WordUtils#capitalize(String)}. * A {@code null} input String returns {@code null}.</p> * * <pre> * StringUtils.capitalize(null) = null * StringUtils.capitalize("") = "" * StringUtils.capitalize("cat") = "Cat" * StringUtils.capitalize("cAt") = "CAt" * </pre> * * @param str the String to capitalize, may be null * @return the capitalized String, {@code null} if null String input * @see org.apache.commons.lang3.text.WordUtils#capitalize(String) * @see #uncapitalize(String) * @since 2.0 */ public static String capitalize(String str) { int strLen; if (str == null || (strLen = str.length()) == 0) { return str; } return new StringBuilder(strLen) .append(Character.toTitleCase(str.charAt(0))) .append(str.substring(1)) .toString(); } /** * <p>Uncapitalizes a String changing the first letter to title case as * per {@link Character#toLowerCase(char)}. No other letters are changed.</p> * * <p>For a word based algorithm, see {@link org.apache.commons.lang3.text.WordUtils#uncapitalize(String)}. * A {@code null} input String returns {@code null}.</p> * * <pre> * StringUtils.uncapitalize(null) = null * StringUtils.uncapitalize("") = "" * StringUtils.uncapitalize("Cat") = "cat" * StringUtils.uncapitalize("CAT") = "cAT" * </pre> * * @param str the String to uncapitalize, may be null * @return the uncapitalized String, {@code null} if null String input * @see org.apache.commons.lang3.text.WordUtils#uncapitalize(String) * @see #capitalize(String) * @since 2.0 */ public static String uncapitalize(String str) { int strLen; if (str == null || (strLen = str.length()) == 0) { return str; } return new StringBuilder(strLen) .append(Character.toLowerCase(str.charAt(0))) .append(str.substring(1)) .toString(); } /** * <p>Swaps the case of a String changing upper and title case to * lower case, and lower case to upper case.</p> * * <ul> * <li>Upper case character converts to Lower case</li> * <li>Title case character converts to Lower case</li> * <li>Lower case character converts to Upper case</li> * </ul> * * <p>For a word based algorithm, see {@link org.apache.commons.lang3.text.WordUtils#swapCase(String)}. * A {@code null} input String returns {@code null}.</p> * * <pre> * StringUtils.swapCase(null) = null * StringUtils.swapCase("") = "" * StringUtils.swapCase("The dog has a BONE") = "tHE DOG HAS A bone" * </pre> * * <p>NOTE: This method changed in Lang version 2.0. * It no longer performs a word based algorithm. * If you only use ASCII, you will notice no change. * That functionality is available in org.apache.commons.lang3.text.WordUtils.</p> * * @param str the String to swap case, may be null * @return the changed String, {@code null} if null String input */ public static String swapCase(String str) { if (StringUtils.isEmpty(str)) { return str; } char[] buffer = str.toCharArray(); for (int i = 0; i < buffer.length; i++) { char ch = buffer[i]; if (Character.isUpperCase(ch)) { buffer[i] = Character.toLowerCase(ch); } else if (Character.isTitleCase(ch)) { buffer[i] = Character.toLowerCase(ch); } else if (Character.isLowerCase(ch)) { buffer[i] = Character.toUpperCase(ch); } } return new String(buffer); } // Character Tests //----------------------------------------------------------------------- /** * <p>Checks if the CharSequence contains only Unicode letters.</p> * * <p>{@code null} will return {@code false}. * An empty CharSequence (length()=0) will return {@code false}.</p> * * <pre> * StringUtils.isAlpha(null) = false * StringUtils.isAlpha("") = false * StringUtils.isAlpha(" ") = false * StringUtils.isAlpha("abc") = true * StringUtils.isAlpha("ab2c") = false * StringUtils.isAlpha("ab-c") = false * </pre> * * @param cs the CharSequence to check, may be null * @return {@code true} if only contains letters, and is non-null * @since 3.0 Changed signature from isAlpha(String) to isAlpha(CharSequence) * @since 3.0 Changed "" to return false and not true */ public static boolean isAlpha(CharSequence cs) { if (cs == null || cs.length() == 0) { return false; } int sz = cs.length(); for (int i = 0; i < sz; i++) { if (Character.isLetter(cs.charAt(i)) == false) { return false; } } return true; } /** * <p>Checks if the CharSequence contains only Unicode letters and * space (' ').</p> * * <p>{@code null} will return {@code false} * An empty CharSequence (length()=0) will return {@code true}.</p> * * <pre> * StringUtils.isAlphaSpace(null) = false * StringUtils.isAlphaSpace("") = true * StringUtils.isAlphaSpace(" ") = true * StringUtils.isAlphaSpace("abc") = true * StringUtils.isAlphaSpace("ab c") = true * StringUtils.isAlphaSpace("ab2c") = false * StringUtils.isAlphaSpace("ab-c") = false * </pre> * * @param cs the CharSequence to check, may be null * @return {@code true} if only contains letters and space, * and is non-null * @since 3.0 Changed signature from isAlphaSpace(String) to isAlphaSpace(CharSequence) */ public static boolean isAlphaSpace(CharSequence cs) { if (cs == null) { return false; } int sz = cs.length(); for (int i = 0; i < sz; i++) { if (Character.isLetter(cs.charAt(i)) == false && cs.charAt(i) != ' ') { return false; } } return true; } /** * <p>Checks if the CharSequence contains only Unicode letters or digits.</p> * * <p>{@code null} will return {@code false}. * An empty CharSequence (length()=0) will return {@code false}.</p> * * <pre> * StringUtils.isAlphanumeric(null) = false * StringUtils.isAlphanumeric("") = false * StringUtils.isAlphanumeric(" ") = false * StringUtils.isAlphanumeric("abc") = true * StringUtils.isAlphanumeric("ab c") = false * StringUtils.isAlphanumeric("ab2c") = true * StringUtils.isAlphanumeric("ab-c") = false * </pre> * * @param cs the CharSequence to check, may be null * @return {@code true} if only contains letters or digits, * and is non-null * @since 3.0 Changed signature from isAlphanumeric(String) to isAlphanumeric(CharSequence) * @since 3.0 Changed "" to return false and not true */ public static boolean isAlphanumeric(CharSequence cs) { if (cs == null || cs.length() == 0) { return false; } int sz = cs.length(); for (int i = 0; i < sz; i++) { if (Character.isLetterOrDigit(cs.charAt(i)) == false) { return false; } } return true; } /** * <p>Checks if the CharSequence contains only Unicode letters, digits * or space ({@code ' '}).</p> * * <p>{@code null} will return {@code false}. * An empty CharSequence (length()=0) will return {@code true}.</p> * * <pre> * StringUtils.isAlphanumericSpace(null) = false * StringUtils.isAlphanumericSpace("") = true * StringUtils.isAlphanumericSpace(" ") = true * StringUtils.isAlphanumericSpace("abc") = true * StringUtils.isAlphanumericSpace("ab c") = true * StringUtils.isAlphanumericSpace("ab2c") = true * StringUtils.isAlphanumericSpace("ab-c") = false * </pre> * * @param cs the CharSequence to check, may be null * @return {@code true} if only contains letters, digits or space, * and is non-null * @since 3.0 Changed signature from isAlphanumericSpace(String) to isAlphanumericSpace(CharSequence) */ public static boolean isAlphanumericSpace(CharSequence cs) { if (cs == null) { return false; } int sz = cs.length(); for (int i = 0; i < sz; i++) { if (Character.isLetterOrDigit(cs.charAt(i)) == false && cs.charAt(i) != ' ') { return false; } } return true; } /** * <p>Checks if the CharSequence contains only Unicode digits. * A decimal point is not a Unicode digit and returns false.</p> * * <p>{@code null} will return {@code false}. * An empty CharSequence (length()=0) will return {@code false}.</p> * * <pre> * StringUtils.isNumeric(null) = false * StringUtils.isNumeric("") = false * StringUtils.isNumeric(" ") = false * StringUtils.isNumeric("123") = true * StringUtils.isNumeric("12 3") = false * StringUtils.isNumeric("ab2c") = false * StringUtils.isNumeric("12-3") = false * StringUtils.isNumeric("12.3") = false * </pre> * * @param cs the CharSequence to check, may be null * @return {@code true} if only contains digits, and is non-null * @since 3.0 Changed signature from isNumeric(String) to isNumeric(CharSequence) * @since 3.0 Changed "" to return false and not true */ public static boolean isNumeric(CharSequence cs) { if (cs == null || cs.length() == 0) { return false; } int sz = cs.length(); for (int i = 0; i < sz; i++) { if (Character.isDigit(cs.charAt(i)) == false) { return false; } } return true; } /** * <p>Checks if the CharSequence contains only Unicode digits or space * ({@code ' '}). * A decimal point is not a Unicode digit and returns false.</p> * * <p>{@code null} will return {@code false}. * An empty CharSequence (length()=0) will return {@code true}.</p> * * <pre> * StringUtils.isNumericSpace(null) = false * StringUtils.isNumericSpace("") = true * StringUtils.isNumericSpace(" ") = true * StringUtils.isNumericSpace("123") = true * StringUtils.isNumericSpace("12 3") = true * StringUtils.isNumericSpace("ab2c") = false * StringUtils.isNumericSpace("12-3") = false * StringUtils.isNumericSpace("12.3") = false * </pre> * * @param cs the CharSequence to check, may be null * @return {@code true} if only contains digits or space, * and is non-null * @since 3.0 Changed signature from isNumericSpace(String) to isNumericSpace(CharSequence) */ public static boolean isNumericSpace(CharSequence cs) { if (cs == null) { return false; } int sz = cs.length(); for (int i = 0; i < sz; i++) { if (Character.isDigit(cs.charAt(i)) == false && cs.charAt(i) != ' ') { return false; } } return true; } /** * <p>Checks if the CharSequence contains only whitespace.</p> * * <p>{@code null} will return {@code false}. * An empty CharSequence (length()=0) will return {@code true}.</p> * * <pre> * StringUtils.isWhitespace(null) = false * StringUtils.isWhitespace("") = true * StringUtils.isWhitespace(" ") = true * StringUtils.isWhitespace("abc") = false * StringUtils.isWhitespace("ab2c") = false * StringUtils.isWhitespace("ab-c") = false * </pre> * * @param cs the CharSequence to check, may be null * @return {@code true} if only contains whitespace, and is non-null * @since 2.0 * @since 3.0 Changed signature from isWhitespace(String) to isWhitespace(CharSequence) */ public static boolean isWhitespace(CharSequence cs) { if (cs == null) { return false; } int sz = cs.length(); for (int i = 0; i < sz; i++) { if (Character.isWhitespace(cs.charAt(i)) == false) { return false; } } return true; } /** * <p>Checks if the CharSequence contains only lowercase characters.</p> * * <p>{@code null} will return {@code false}. * An empty CharSequence (length()=0) will return {@code false}.</p> * * <pre> * StringUtils.isAllLowerCase(null) = false * StringUtils.isAllLowerCase("") = false * StringUtils.isAllLowerCase(" ") = false * StringUtils.isAllLowerCase("abc") = true * StringUtils.isAllLowerCase("abC") = false * </pre> * * @param cs the CharSequence to check, may be null * @return {@code true} if only contains lowercase characters, and is non-null * @since 2.5 * @since 3.0 Changed signature from isAllLowerCase(String) to isAllLowerCase(CharSequence) */ public static boolean isAllLowerCase(CharSequence cs) { if (cs == null || isEmpty(cs)) { return false; } int sz = cs.length(); for (int i = 0; i < sz; i++) { if (Character.isLowerCase(cs.charAt(i)) == false) { return false; } } return true; } /** * <p>Checks if the CharSequence contains only uppercase characters.</p> * * <p>{@code null} will return {@code false}. * An empty String (length()=0) will return {@code false}.</p> * * <pre> * StringUtils.isAllUpperCase(null) = false * StringUtils.isAllUpperCase("") = false * StringUtils.isAllUpperCase(" ") = false * StringUtils.isAllUpperCase("ABC") = true * StringUtils.isAllUpperCase("aBC") = false * </pre> * * @param cs the CharSequence to check, may be null * @return {@code true} if only contains uppercase characters, and is non-null * @since 2.5 * @since 3.0 Changed signature from isAllUpperCase(String) to isAllUpperCase(CharSequence) */ public static boolean isAllUpperCase(CharSequence cs) { if (cs == null || isEmpty(cs)) { return false; } int sz = cs.length(); for (int i = 0; i < sz; i++) { if (Character.isUpperCase(cs.charAt(i)) == false) { return false; } } return true; } // Defaults //----------------------------------------------------------------------- /** * <p>Returns either the passed in String, * or if the String is {@code null}, an empty String ("").</p> * * <pre> * StringUtils.defaultString(null) = "" * StringUtils.defaultString("") = "" * StringUtils.defaultString("bat") = "bat" * </pre> * * @see ObjectUtils#toString(Object) * @see String#valueOf(Object) * @param str the String to check, may be null * @return the passed in String, or the empty String if it * was {@code null} */ public static String defaultString(String str) { return str == null ? EMPTY : str; } /** * <p>Returns either the passed in String, or if the String is * {@code null}, the value of {@code defaultStr}.</p> * * <pre> * StringUtils.defaultString(null, "NULL") = "NULL" * StringUtils.defaultString("", "NULL") = "" * StringUtils.defaultString("bat", "NULL") = "bat" * </pre> * * @see ObjectUtils#toString(Object,String) * @see String#valueOf(Object) * @param str the String to check, may be null * @param defaultStr the default String to return * if the input is {@code null}, may be null * @return the passed in String, or the default if it was {@code null} */ public static String defaultString(String str, String defaultStr) { return str == null ? defaultStr : str; } /** * <p>Returns either the passed in CharSequence, or if the CharSequence is * whitespace, empty ("") or {@code null}, the value of {@code defaultStr}.</p> * * <pre> * StringUtils.defaultIfBlank(null, "NULL") = "NULL" * StringUtils.defaultIfBlank("", "NULL") = "NULL" * StringUtils.defaultIfBlank(" ", "NULL") = "NULL" * StringUtils.defaultIfBlank("bat", "NULL") = "bat" * StringUtils.defaultIfBlank("", null) = null * </pre> * @param <T> the specific kind of CharSequence * @param str the CharSequence to check, may be null * @param defaultStr the default CharSequence to return * if the input is whitespace, empty ("") or {@code null}, may be null * @return the passed in CharSequence, or the default * @see StringUtils#defaultString(String, String) */ public static <T extends CharSequence> T defaultIfBlank(T str, T defaultStr) { return StringUtils.isBlank(str) ? defaultStr : str; } /** * <p>Returns either the passed in CharSequence, or if the CharSequence is * empty or {@code null}, the value of {@code defaultStr}.</p> * * <pre> * StringUtils.defaultIfEmpty(null, "NULL") = "NULL" * StringUtils.defaultIfEmpty("", "NULL") = "NULL" * StringUtils.defaultIfEmpty(" ", "NULL") = " " * StringUtils.defaultIfEmpty("bat", "NULL") = "bat" * StringUtils.defaultIfEmpty("", null) = null * </pre> * @param <T> the specific kind of CharSequence * @param str the CharSequence to check, may be null * @param defaultStr the default CharSequence to return * if the input is empty ("") or {@code null}, may be null * @return the passed in CharSequence, or the default * @see StringUtils#defaultString(String, String) */ public static <T extends CharSequence> T defaultIfEmpty(T str, T defaultStr) { return StringUtils.isEmpty(str) ? defaultStr : str; } // Reversing //----------------------------------------------------------------------- /** * <p>Reverses a String as per {@link StringBuilder#reverse()}.</p> * * <p>A {@code null} String returns {@code null}.</p> * * <pre> * StringUtils.reverse(null) = null * StringUtils.reverse("") = "" * StringUtils.reverse("bat") = "tab" * </pre> * * @param str the String to reverse, may be null * @return the reversed String, {@code null} if null String input */ public static String reverse(String str) { if (str == null) { return null; } return new StringBuilder(str).reverse().toString(); } // Abbreviating //----------------------------------------------------------------------- /** * <p>Abbreviates a String using ellipses. This will turn * "Now is the time for all good men" into "Now is the time for..."</p> * * <p>Specifically: * <ul> * <li>If {@code str} is less than {@code maxWidth} characters * long, return it.</li> * <li>Else abbreviate it to {@code (substring(str, 0, max-3) + "...")}.</li> * <li>If {@code maxWidth} is less than {@code 4}, throw an * {@code IllegalArgumentException}.</li> * <li>In no case will it return a String of length greater than * {@code maxWidth}.</li> * </ul> * </p> * * <pre> * StringUtils.abbreviate(null, *) = null * StringUtils.abbreviate("", 4) = "" * StringUtils.abbreviate("abcdefg", 6) = "abc..." * StringUtils.abbreviate("abcdefg", 7) = "abcdefg" * StringUtils.abbreviate("abcdefg", 8) = "abcdefg" * StringUtils.abbreviate("abcdefg", 4) = "a..." * StringUtils.abbreviate("abcdefg", 3) = IllegalArgumentException * </pre> * * @param str the String to check, may be null * @param maxWidth maximum length of result String, must be at least 4 * @return abbreviated String, {@code null} if null String input * @throws IllegalArgumentException if the width is too small * @since 2.0 */ public static String abbreviate(String str, int maxWidth) { return abbreviate(str, 0, maxWidth); } /** * <p>Abbreviates a String using ellipses. This will turn * "Now is the time for all good men" into "...is the time for..."</p> * * <p>Works like {@code abbreviate(String, int)}, but allows you to specify * a "left edge" offset. Note that this left edge is not necessarily going to * be the leftmost character in the result, or the first character following the * ellipses, but it will appear somewhere in the result. * * <p>In no case will it return a String of length greater than * {@code maxWidth}.</p> * * <pre> * StringUtils.abbreviate(null, *, *) = null * StringUtils.abbreviate("", 0, 4) = "" * StringUtils.abbreviate("abcdefghijklmno", -1, 10) = "abcdefg..." * StringUtils.abbreviate("abcdefghijklmno", 0, 10) = "abcdefg..." * StringUtils.abbreviate("abcdefghijklmno", 1, 10) = "abcdefg..." * StringUtils.abbreviate("abcdefghijklmno", 4, 10) = "abcdefg..." * StringUtils.abbreviate("abcdefghijklmno", 5, 10) = "...fghi..." * StringUtils.abbreviate("abcdefghijklmno", 6, 10) = "...ghij..." * StringUtils.abbreviate("abcdefghijklmno", 8, 10) = "...ijklmno" * StringUtils.abbreviate("abcdefghijklmno", 10, 10) = "...ijklmno" * StringUtils.abbreviate("abcdefghijklmno", 12, 10) = "...ijklmno" * StringUtils.abbreviate("abcdefghij", 0, 3) = IllegalArgumentException * StringUtils.abbreviate("abcdefghij", 5, 6) = IllegalArgumentException * </pre> * * @param str the String to check, may be null * @param offset left edge of source String * @param maxWidth maximum length of result String, must be at least 4 * @return abbreviated String, {@code null} if null String input * @throws IllegalArgumentException if the width is too small * @since 2.0 */ public static String abbreviate(String str, int offset, int maxWidth) { if (str == null) { return null; } if (maxWidth < 4) { throw new IllegalArgumentException("Minimum abbreviation width is 4"); } if (str.length() <= maxWidth) { return str; } if (offset > str.length()) { offset = str.length(); } if (str.length() - offset < maxWidth - 3) { offset = str.length() - (maxWidth - 3); } final String abrevMarker = "..."; if (offset <= 4) { return str.substring(0, maxWidth - 3) + abrevMarker; } if (maxWidth < 7) { throw new IllegalArgumentException("Minimum abbreviation width with offset is 7"); } if (offset + maxWidth - 3 < str.length()) { return abrevMarker + abbreviate(str.substring(offset), maxWidth - 3); } return abrevMarker + str.substring(str.length() - (maxWidth - 3)); } /** * <p>Abbreviates a String to the length passed, replacing the middle characters with the supplied * replacement String.</p> * * <p>This abbreviation only occurs if the following criteria is met: * <ul> * <li>Neither the String for abbreviation nor the replacement String are null or empty </li> * <li>The length to truncate to is less than the length of the supplied String</li> * <li>The length to truncate to is greater than 0</li> * <li>The abbreviated String will have enough room for the length supplied replacement String * and the first and last characters of the supplied String for abbreviation</li> * </ul> * Otherwise, the returned String will be the same as the supplied String for abbreviation. * </p> * * <pre> * StringUtils.abbreviateMiddle(null, null, 0) = null * StringUtils.abbreviateMiddle("abc", null, 0) = "abc" * StringUtils.abbreviateMiddle("abc", ".", 0) = "abc" * StringUtils.abbreviateMiddle("abc", ".", 3) = "abc" * StringUtils.abbreviateMiddle("abcdef", ".", 4) = "ab.f" * </pre> * * @param str the String to abbreviate, may be null * @param middle the String to replace the middle characters with, may be null * @param length the length to abbreviate {@code str} to. * @return the abbreviated String if the above criteria is met, or the original String supplied for abbreviation. * @since 2.5 */ public static String abbreviateMiddle(String str, String middle, int length) { if (isEmpty(str) || isEmpty(middle)) { return str; } if (length >= str.length() || length < middle.length()+2) { return str; } int targetSting = length-middle.length(); int startOffset = targetSting/2+targetSting%2; int endOffset = str.length()-targetSting/2; StringBuilder builder = new StringBuilder(length); builder.append(str.substring(0,startOffset)); builder.append(middle); builder.append(str.substring(endOffset)); return builder.toString(); } // Difference //----------------------------------------------------------------------- /** * <p>Compares two Strings, and returns the portion where they differ. * (More precisely, return the remainder of the second String, * starting from where it's different from the first.)</p> * * <p>For example, * {@code difference("i am a machine", "i am a robot") -> "robot"}.</p> * * <pre> * StringUtils.difference(null, null) = null * StringUtils.difference("", "") = "" * StringUtils.difference("", "abc") = "abc" * StringUtils.difference("abc", "") = "" * StringUtils.difference("abc", "abc") = "" * StringUtils.difference("ab", "abxyz") = "xyz" * StringUtils.difference("abcde", "abxyz") = "xyz" * StringUtils.difference("abcde", "xyz") = "xyz" * </pre> * * @param str1 the first String, may be null * @param str2 the second String, may be null * @return the portion of str2 where it differs from str1; returns the * empty String if they are equal * @since 2.0 */ public static String difference(String str1, String str2) { if (str1 == null) { return str2; } if (str2 == null) { return str1; } int at = indexOfDifference(str1, str2); if (at == INDEX_NOT_FOUND) { return EMPTY; } return str2.substring(at); } /** * <p>Compares two CharSequences, and returns the index at which the * CharSequences begin to differ.</p> * * <p>For example, * {@code indexOfDifference("i am a machine", "i am a robot") -> 7}</p> * * <pre> * StringUtils.indexOfDifference(null, null) = -1 * StringUtils.indexOfDifference("", "") = -1 * StringUtils.indexOfDifference("", "abc") = 0 * StringUtils.indexOfDifference("abc", "") = 0 * StringUtils.indexOfDifference("abc", "abc") = -1 * StringUtils.indexOfDifference("ab", "abxyz") = 2 * StringUtils.indexOfDifference("abcde", "abxyz") = 2 * StringUtils.indexOfDifference("abcde", "xyz") = 0 * </pre> * * @param cs1 the first CharSequence, may be null * @param cs2 the second CharSequence, may be null * @return the index where cs1 and cs2 begin to differ; -1 if they are equal * @since 2.0 * @since 3.0 Changed signature from indexOfDifference(String, String) to * indexOfDifference(CharSequence, CharSequence) */ public static int indexOfDifference(CharSequence cs1, CharSequence cs2) { if (cs1 == cs2) { return INDEX_NOT_FOUND; } if (cs1 == null || cs2 == null) { return 0; } int i; for (i = 0; i < cs1.length() && i < cs2.length(); ++i) { if (cs1.charAt(i) != cs2.charAt(i)) { break; } } if (i < cs2.length() || i < cs1.length()) { return i; } return INDEX_NOT_FOUND; } /** * <p>Compares all CharSequences in an array and returns the index at which the * CharSequences begin to differ.</p> * * <p>For example, * <code>indexOfDifference(new String[] {"i am a machine", "i am a robot"}) -> 7</code></p> * * <pre> * StringUtils.indexOfDifference(null) = -1 * StringUtils.indexOfDifference(new String[] {}) = -1 * StringUtils.indexOfDifference(new String[] {"abc"}) = -1 * StringUtils.indexOfDifference(new String[] {null, null}) = -1 * StringUtils.indexOfDifference(new String[] {"", ""}) = -1 * StringUtils.indexOfDifference(new String[] {"", null}) = 0 * StringUtils.indexOfDifference(new String[] {"abc", null, null}) = 0 * StringUtils.indexOfDifference(new String[] {null, null, "abc"}) = 0 * StringUtils.indexOfDifference(new String[] {"", "abc"}) = 0 * StringUtils.indexOfDifference(new String[] {"abc", ""}) = 0 * StringUtils.indexOfDifference(new String[] {"abc", "abc"}) = -1 * StringUtils.indexOfDifference(new String[] {"abc", "a"}) = 1 * StringUtils.indexOfDifference(new String[] {"ab", "abxyz"}) = 2 * StringUtils.indexOfDifference(new String[] {"abcde", "abxyz"}) = 2 * StringUtils.indexOfDifference(new String[] {"abcde", "xyz"}) = 0 * StringUtils.indexOfDifference(new String[] {"xyz", "abcde"}) = 0 * StringUtils.indexOfDifference(new String[] {"i am a machine", "i am a robot"}) = 7 * </pre> * * @param css array of CharSequences, entries may be null * @return the index where the strings begin to differ; -1 if they are all equal * @since 2.4 * @since 3.0 Changed signature from indexOfDifference(String...) to indexOfDifference(CharSequence...) */ public static int indexOfDifference(CharSequence... css) { if (css == null || css.length <= 1) { return INDEX_NOT_FOUND; } boolean anyStringNull = false; boolean allStringsNull = true; int arrayLen = css.length; int shortestStrLen = Integer.MAX_VALUE; int longestStrLen = 0; // find the min and max string lengths; this avoids checking to make // sure we are not exceeding the length of the string each time through // the bottom loop. for (int i = 0; i < arrayLen; i++) { if (css[i] == null) { anyStringNull = true; shortestStrLen = 0; } else { allStringsNull = false; shortestStrLen = Math.min(css[i].length(), shortestStrLen); longestStrLen = Math.max(css[i].length(), longestStrLen); } } // handle lists containing all nulls or all empty strings if (allStringsNull || longestStrLen == 0 && !anyStringNull) { return INDEX_NOT_FOUND; } // handle lists containing some nulls or some empty strings if (shortestStrLen == 0) { return 0; } // find the position with the first difference across all strings int firstDiff = -1; for (int stringPos = 0; stringPos < shortestStrLen; stringPos++) { char comparisonChar = css[0].charAt(stringPos); for (int arrayPos = 1; arrayPos < arrayLen; arrayPos++) { if (css[arrayPos].charAt(stringPos) != comparisonChar) { firstDiff = stringPos; break; } } if (firstDiff != -1) { break; } } if (firstDiff == -1 && shortestStrLen != longestStrLen) { // we compared all of the characters up to the length of the // shortest string and didn't find a match, but the string lengths // vary, so return the length of the shortest string. return shortestStrLen; } return firstDiff; } /** * <p>Compares all Strings in an array and returns the initial sequence of * characters that is common to all of them.</p> * * <p>For example, * <code>getCommonPrefix(new String[] {"i am a machine", "i am a robot"}) -> "i am a "</code></p> * * <pre> * StringUtils.getCommonPrefix(null) = "" * StringUtils.getCommonPrefix(new String[] {}) = "" * StringUtils.getCommonPrefix(new String[] {"abc"}) = "abc" * StringUtils.getCommonPrefix(new String[] {null, null}) = "" * StringUtils.getCommonPrefix(new String[] {"", ""}) = "" * StringUtils.getCommonPrefix(new String[] {"", null}) = "" * StringUtils.getCommonPrefix(new String[] {"abc", null, null}) = "" * StringUtils.getCommonPrefix(new String[] {null, null, "abc"}) = "" * StringUtils.getCommonPrefix(new String[] {"", "abc"}) = "" * StringUtils.getCommonPrefix(new String[] {"abc", ""}) = "" * StringUtils.getCommonPrefix(new String[] {"abc", "abc"}) = "abc" * StringUtils.getCommonPrefix(new String[] {"abc", "a"}) = "a" * StringUtils.getCommonPrefix(new String[] {"ab", "abxyz"}) = "ab" * StringUtils.getCommonPrefix(new String[] {"abcde", "abxyz"}) = "ab" * StringUtils.getCommonPrefix(new String[] {"abcde", "xyz"}) = "" * StringUtils.getCommonPrefix(new String[] {"xyz", "abcde"}) = "" * StringUtils.getCommonPrefix(new String[] {"i am a machine", "i am a robot"}) = "i am a " * </pre> * * @param strs array of String objects, entries may be null * @return the initial sequence of characters that are common to all Strings * in the array; empty String if the array is null, the elements are all null * or if there is no common prefix. * @since 2.4 */ public static String getCommonPrefix(String... strs) { if (strs == null || strs.length == 0) { return EMPTY; } int smallestIndexOfDiff = indexOfDifference(strs); if (smallestIndexOfDiff == INDEX_NOT_FOUND) { // all strings were identical if (strs[0] == null) { return EMPTY; } return strs[0]; } else if (smallestIndexOfDiff == 0) { // there were no common initial characters return EMPTY; } else { // we found a common initial character sequence return strs[0].substring(0, smallestIndexOfDiff); } } // Misc //----------------------------------------------------------------------- /** * <p>Find the Levenshtein distance between two Strings.</p> * * <p>This is the number of changes needed to change one String into * another, where each change is a single character modification (deletion, * insertion or substitution).</p> * * <p>The previous implementation of the Levenshtein distance algorithm * was from <a href="http://www.merriampark.com/ld.htm">http://www.merriampark.com/ld.htm</a></p> * * <p>Chas Emerick has written an implementation in Java, which avoids an OutOfMemoryError * which can occur when my Java implementation is used with very large strings.<br> * This implementation of the Levenshtein distance algorithm * is from <a href="http://www.merriampark.com/ldjava.htm">http://www.merriampark.com/ldjava.htm</a></p> * * <pre> * StringUtils.getLevenshteinDistance(null, *) = IllegalArgumentException * StringUtils.getLevenshteinDistance(*, null) = IllegalArgumentException * StringUtils.getLevenshteinDistance("","") = 0 * StringUtils.getLevenshteinDistance("","a") = 1 * StringUtils.getLevenshteinDistance("aaapppp", "") = 7 * StringUtils.getLevenshteinDistance("frog", "fog") = 1 * StringUtils.getLevenshteinDistance("fly", "ant") = 3 * StringUtils.getLevenshteinDistance("elephant", "hippo") = 7 * StringUtils.getLevenshteinDistance("hippo", "elephant") = 7 * StringUtils.getLevenshteinDistance("hippo", "zzzzzzzz") = 8 * StringUtils.getLevenshteinDistance("hello", "hallo") = 1 * </pre> * * @param s the first String, must not be null * @param t the second String, must not be null * @return result distance * @throws IllegalArgumentException if either String input {@code null} * @since 3.0 Changed signature from getLevenshteinDistance(String, String) to * getLevenshteinDistance(CharSequence, CharSequence) */ public static int getLevenshteinDistance(CharSequence s, CharSequence t) { if (s == null || t == null) { throw new IllegalArgumentException("Strings must not be null"); } /* The difference between this impl. and the previous is that, rather than creating and retaining a matrix of size s.length() + 1 by t.length() + 1, we maintain two single-dimensional arrays of length s.length() + 1. The first, d, is the 'current working' distance array that maintains the newest distance cost counts as we iterate through the characters of String s. Each time we increment the index of String t we are comparing, d is copied to p, the second int[]. Doing so allows us to retain the previous cost counts as required by the algorithm (taking the minimum of the cost count to the left, up one, and diagonally up and to the left of the current cost count being calculated). (Note that the arrays aren't really copied anymore, just switched...this is clearly much better than cloning an array or doing a System.arraycopy() each time through the outer loop.) Effectively, the difference between the two implementations is this one does not cause an out of memory condition when calculating the LD over two very large strings. */ int n = s.length(); // length of s int m = t.length(); // length of t if (n == 0) { return m; } else if (m == 0) { return n; } if (n > m) { // swap the input strings to consume less memory CharSequence tmp = s; s = t; t = tmp; n = m; m = t.length(); } int p[] = new int[n + 1]; //'previous' cost array, horizontally int d[] = new int[n + 1]; // cost array, horizontally int _d[]; //placeholder to assist in swapping p and d // indexes into strings s and t int i; // iterates through s int j; // iterates through t char t_j; // jth character of t int cost; // cost for (i = 0; i <= n; i++) { p[i] = i; } for (j = 1; j <= m; j++) { t_j = t.charAt(j - 1); d[0] = j; for (i = 1; i <= n; i++) { cost = s.charAt(i - 1) == t_j ? 0 : 1; // minimum of cell to the left+1, to the top+1, diagonally left and up +cost d[i] = Math.min(Math.min(d[i - 1] + 1, p[i] + 1), p[i - 1] + cost); } // copy current distance counts to 'previous row' distance counts _d = p; p = d; d = _d; } // our last action in the above loop was to switch d and p, so p now // actually has the most recent cost counts return p[n]; } /** * <p>Find the Levenshtein distance between two Strings if it's less than or equal to a given * threshold.</p> * * <p>This is the number of changes needed to change one String into * another, where each change is a single character modification (deletion, * insertion or substitution).</p> * * <p>This implementation follows from Algorithms on Strings, Trees and Sequences by Dan Gusfield * and Chas Emerick's implementation of the Levenshtein distance algorithm from * <a href="http://www.merriampark.com/ld.htm">http://www.merriampark.com/ld.htm</a></p> * * <pre> * StringUtils.getLevenshteinDistance(null, *, *) = IllegalArgumentException * StringUtils.getLevenshteinDistance(*, null, *) = IllegalArgumentException * StringUtils.getLevenshteinDistance(*, *, -1) = IllegalArgumentException * StringUtils.getLevenshteinDistance("","", 0) = 0 * StringUtils.getLevenshteinDistance("aaapppp", "", 8) = 7 * StringUtils.getLevenshteinDistance("aaapppp", "", 7) = 7 * StringUtils.getLevenshteinDistance("aaapppp", "", 6)) = -1 * StringUtils.getLevenshteinDistance("elephant", "hippo", 7) = 7 * StringUtils.getLevenshteinDistance("elephant", "hippo", 6) = -1 * StringUtils.getLevenshteinDistance("hippo", "elephant", 7) = 7 * StringUtils.getLevenshteinDistance("hippo", "elephant", 6) = -1 * </pre> * * @param s the first String, must not be null * @param t the second String, must not be null * @param threshold the target threshold, must not be negative * @return result distance, or {@code -1} if the distance would be greater than the threshold * @throws IllegalArgumentException if either String input {@code null} or negative threshold */ public static int getLevenshteinDistance(CharSequence s, CharSequence t, int threshold) { if (s == null || t == null) { throw new IllegalArgumentException("Strings must not be null"); } if (threshold < 0) { throw new IllegalArgumentException("Threshold must not be negative"); } /* This implementation only computes the distance if it's less than or equal to the threshold value, returning -1 if it's greater. The advantage is performance: unbounded distance is O(nm), but a bound of k allows us to reduce it to O(km) time by only computing a diagonal stripe of width 2k + 1 of the cost table. It is also possible to use this to compute the unbounded Levenshtein distance by starting the threshold at 1 and doubling each time until the distance is found; this is O(dm), where d is the distance. One subtlety comes from needing to ignore entries on the border of our stripe eg. p[] = |#|#|#|* d[] = *|#|#|#| We must ignore the entry to the left of the leftmost member We must ignore the entry above the rightmost member Another subtlety comes from our stripe running off the matrix if the strings aren't of the same size. Since string s is always swapped to be the shorter of the two, the stripe will always run off to the upper right instead of the lower left of the matrix. As a concrete example, suppose s is of length 5, t is of length 7, and our threshold is 1. In this case we're going to walk a stripe of length 3. The matrix would look like so: 1 2 3 4 5 1 |#|#| | | | 2 |#|#|#| | | 3 | |#|#|#| | 4 | | |#|#|#| 5 | | | |#|#| 6 | | | | |#| 7 | | | | | | Note how the stripe leads off the table as there is no possible way to turn a string of length 5 into one of length 7 in edit distance of 1. Additionally, this implementation decreases memory usage by using two single-dimensional arrays and swapping them back and forth instead of allocating an entire n by m matrix. This requires a few minor changes, such as immediately returning when it's detected that the stripe has run off the matrix and initially filling the arrays with large values so that entries we don't compute are ignored. See Algorithms on Strings, Trees and Sequences by Dan Gusfield for some discussion. */ int n = s.length(); // length of s int m = t.length(); // length of t // if one string is empty, the edit distance is necessarily the length of the other if (n == 0) { return m <= threshold ? m : -1; } else if (m == 0) { return n <= threshold ? n : -1; } if (n > m) { // swap the two strings to consume less memory CharSequence tmp = s; s = t; t = tmp; n = m; m = t.length(); } int p[] = new int[n + 1]; // 'previous' cost array, horizontally int d[] = new int[n + 1]; // cost array, horizontally int _d[]; // placeholder to assist in swapping p and d // fill in starting table values int boundary = Math.min(n, threshold) + 1; for (int i = 0; i < boundary; i++) { p[i] = i; } // these fills ensure that the value above the rightmost entry of our // stripe will be ignored in following loop iterations Arrays.fill(p, boundary, p.length, Integer.MAX_VALUE); Arrays.fill(d, Integer.MAX_VALUE); // iterates through t for (int j = 1; j <= m; j++) { char t_j = t.charAt(j - 1); // jth character of t d[0] = j; // compute stripe indices, constrain to array size int min = Math.max(1, j - threshold); int max = Math.min(n, j + threshold); // the stripe may lead off of the table if s and t are of different sizes if (min > max) { return -1; } // ignore entry left of leftmost if (min > 1) { d[min - 1] = Integer.MAX_VALUE; } // iterates through [min, max] in s for (int i = min; i <= max; i++) { if (s.charAt(i - 1) == t_j) { // diagonally left and up d[i] = p[i - 1]; } else { // 1 + minimum of cell to the left, to the top, diagonally left and up d[i] = 1 + Math.min(Math.min(d[i - 1], p[i]), p[i - 1]); } } // copy current distance counts to 'previous row' distance counts _d = p; p = d; d = _d; } // if p[n] is greater than the threshold, there's no guarantee on it being the correct // distance if (p[n] <= threshold) { return p[n]; } else { return -1; } } /** * <p> * Similar to <a * href="http://www.w3.org/TR/xpath/#function-normalize-space">http://www.w3.org/TR/xpath/#function-normalize * -space</a> * </p> * <p> * The function returns the argument string with whitespace normalized by using * <code>{@link #trim(String)}</code> to remove leading and trailing whitespace * and then replacing sequences of whitespace characters by a single space. * </p> * In XML Whitespace characters are the same as those allowed by the <a * href="http://www.w3.org/TR/REC-xml/#NT-S">S</a> production, which is S ::= (#x20 | #x9 | #xD | #xA)+ * <p> * Java's regexp pattern \s defines whitespace as [ \t\n\x0B\f\r] * <p> * For reference: * <ul> * <li>\x0B = vertical tab</li> * <li>\f = #xC = form feed</li> * <li>#x20 = space</li> * <li>#x9 = \t</li> * <li>#xA = \n</li> * <li>#xD = \r</li> * </ul> * </p> * <p> * The difference is that Java's whitespace includes vertical tab and form feed, which this functional will also * normalize. Additionally <code>{@link #trim(String)}</code> removes control characters (char <= 32) from both * ends of this String. * </p> * * @see Pattern * @see #trim(String) * @see <a * href="http://www.w3.org/TR/xpath/#function-normalize-space">http://www.w3.org/TR/xpath/#function-normalize-space</a> * @param str the source String to normalize whitespaces from, may be null * @return the modified string with whitespace normalized, {@code null} if null String input * * @since 3.0 */ public static String normalizeSpace(String str) { if (str == null) { return null; } return WHITESPACE_BLOCK.matcher(trim(str)).replaceAll(" "); } /** * Converts a <code>byte[]</code> to a String using the specified character encoding. * * @param bytes * the byte array to read from * @param charsetName * the encoding to use, if null then use the platform default * @return a new String * @throws UnsupportedEncodingException * If the named charset is not supported * @throws NullPointerException * if the input is null * @since 3.1 */ public static String toString(byte[] bytes, String charsetName) throws UnsupportedEncodingException { return charsetName == null ? new String(bytes) : new String(bytes, charsetName); } }