Java tutorial
/* * Copyright 2002-2006 the original author or authors. * * Licensed 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 * * 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 com.dsj.core.beans; import java.util.ArrayList; import java.util.Arrays; import java.util.Collection; import java.util.Iterator; import java.util.LinkedList; import java.util.List; import java.util.Locale; import java.util.Properties; import java.util.Set; import java.util.StringTokenizer; import java.util.TreeSet; /** * Miscellaneous string utility methods. Mainly for internal use * within the framework; consider Jakarta's Commons Lang for a more * comprehensive suite of string utilities. * * <p>This class delivers some simple functionality that should really * be provided by the core Java String and StringBuffer classes, such * as the ability to replace all occurrences of a given substring in a * target string. It also provides easy-to-use methods to convert between * delimited strings, such as CSV strings, and collections and arrays. * * @author Rod Johnson * @author Juergen Hoeller * @author Keith Donald * @author Rob Harrop * @since 16 April 2001 * @see org.apache.commons.lang.StringUtils */ public abstract class StringUtils { private static final String FOLDER_SEPARATOR = "/"; private static final String WINDOWS_FOLDER_SEPARATOR = "\\"; private static final String TOP_PATH = ".."; private static final String CURRENT_PATH = "."; private static final char EXTENSION_SEPARATOR = '.'; //--------------------------------------------------------------------- // General convenience methods for working with Strings //--------------------------------------------------------------------- /** * Check if a String has length. * <p><pre> * StringUtils.hasLength(null) = false * StringUtils.hasLength("") = false * StringUtils.hasLength(" ") = true * StringUtils.hasLength("Hello") = true * </pre> * @param str the String to check, may be <code>null</code> * @return <code>true</code> if the String is not null and has length */ public static boolean hasLength(String str) { return (str != null && str.length() > 0); } /** * Check if a String has text. More specifically, returns <code>true</code> * if the string not <code>null<code>, it's <code>length is > 0</code>, and * it has at least one non-whitespace character. * <p><pre> * StringUtils.hasText(null) = false * StringUtils.hasText("") = false * StringUtils.hasText(" ") = false * StringUtils.hasText("12345") = true * StringUtils.hasText(" 12345 ") = true * </pre> * @param str the String to check, may be <code>null</code> * @return <code>true</code> if the String is not null, length > 0, * and not whitespace only * @see java.lang.Character#isWhitespace */ public static boolean hasText(String str) { int strLen; if (str == null || (strLen = str.length()) == 0) { return false; } for (int i = 0; i < strLen; i++) { if (!Character.isWhitespace(str.charAt(i))) { return true; } } return false; } /** * Trim leading and trailing whitespace from the given String. * @param str the String to check * @return the trimmed String * @see java.lang.Character#isWhitespace */ public static String trimWhitespace(String str) { if (!hasLength(str)) { return str; } StringBuffer buf = new StringBuffer(str); while (buf.length() > 0 && Character.isWhitespace(buf.charAt(0))) { buf.deleteCharAt(0); } while (buf.length() > 0 && Character.isWhitespace(buf.charAt(buf.length() - 1))) { buf.deleteCharAt(buf.length() - 1); } return buf.toString(); } /** * Trim leading whitespace from the given String. * @param str the String to check * @return the trimmed String * @see java.lang.Character#isWhitespace */ public static String trimLeadingWhitespace(String str) { if (!hasLength(str)) { return str; } StringBuffer buf = new StringBuffer(str); while (buf.length() > 0 && Character.isWhitespace(buf.charAt(0))) { buf.deleteCharAt(0); } return buf.toString(); } /** * Trim trailing whitespace from the given String. * @param str the String to check * @return the trimmed String * @see java.lang.Character#isWhitespace */ public static String trimTrailingWhitespace(String str) { if (!hasLength(str)) { return str; } StringBuffer buf = new StringBuffer(str); while (buf.length() > 0 && Character.isWhitespace(buf.charAt(buf.length() - 1))) { buf.deleteCharAt(buf.length() - 1); } return buf.toString(); } /** * Test if the given String starts with the specified prefix, * ignoring upper/lower case. * @param str the String to check * @param prefix the prefix to look for * @see java.lang.String#startsWith */ public static boolean startsWithIgnoreCase(String str, String prefix) { if (str == null || prefix == null) { return false; } if (str.startsWith(prefix)) { return true; } if (str.length() < prefix.length()) { return false; } String lcStr = str.substring(0, prefix.length()).toLowerCase(); String lcPrefix = prefix.toLowerCase(); return lcStr.equals(lcPrefix); } /** * Test if the given String ends with the specified suffix, * ignoring upper/lower case. * @param str the String to check * @param suffix the suffix to look for * @see java.lang.String#endsWith */ public static boolean endsWithIgnoreCase(String str, String suffix) { if (str == null || suffix == null) { return false; } if (str.endsWith(suffix)) { return true; } if (str.length() < suffix.length()) { return false; } String lcStr = str.substring(str.length() - suffix.length()).toLowerCase(); String lcSuffix = suffix.toLowerCase(); return lcStr.equals(lcSuffix); } /** * Count the occurrences of the substring in string s. * @param str string to search in. Return 0 if this is null. * @param sub string to search for. Return 0 if this is null. */ public static int countOccurrencesOf(String str, String sub) { if (str == null || sub == null || str.length() == 0 || sub.length() == 0) { return 0; } int count = 0, pos = 0, idx = 0; while ((idx = str.indexOf(sub, pos)) != -1) { ++count; pos = idx + sub.length(); } return count; } /** * Replace all occurences of a substring within a string with * another string. * @param inString String to examine * @param oldPattern String to replace * @param newPattern String to insert * @return a String with the replacements */ public static String replace(String inString, String oldPattern, String newPattern) { if (inString == null) { return null; } if (oldPattern == null || newPattern == null) { return inString; } StringBuffer sbuf = new StringBuffer(); // output StringBuffer we'll build up int pos = 0; // our position in the old string int index = inString.indexOf(oldPattern); // the index of an occurrence we've found, or -1 int patLen = oldPattern.length(); while (index >= 0) { sbuf.append(inString.substring(pos, index)); sbuf.append(newPattern); pos = index + patLen; index = inString.indexOf(oldPattern, pos); } sbuf.append(inString.substring(pos)); // remember to append any characters to the right of a match return sbuf.toString(); } /** * Delete all occurrences of the given substring. * @param pattern the pattern to delete all occurrences of */ public static String delete(String inString, String pattern) { return replace(inString, pattern, ""); } /** * Delete any character in a given string. * @param charsToDelete a set of characters to delete. * E.g. "az\n" will delete 'a's, 'z's and new lines. */ public static String deleteAny(String inString, String charsToDelete) { if (inString == null || charsToDelete == null) { return inString; } StringBuffer out = new StringBuffer(); for (int i = 0; i < inString.length(); i++) { char c = inString.charAt(i); if (charsToDelete.indexOf(c) == -1) { out.append(c); } } return out.toString(); } //--------------------------------------------------------------------- // Convenience methods for working with formatted Strings //--------------------------------------------------------------------- /** * Quote the given String with single quotes. * @param str the input String (e.g. "myString") * @return the quoted String (e.g. "'myString'"), * or <code>null<code> if the input was <code>null</code> */ public static String quote(String str) { return (str != null ? "'" + str + "'" : null); } /** * Turn the given Object into a String with single quotes * if it is a String; keeping the Object as-is else. * @param obj the input Object (e.g. "myString") * @return the quoted String (e.g. "'myString'"), * or the input object as-is if not a String */ public static Object quoteIfString(Object obj) { return (obj instanceof String ? quote((String) obj) : obj); } /** * Unqualify a string qualified by a '.' dot character. For example, * "this.name.is.qualified", returns "qualified". * @param qualifiedName the qualified name */ public static String unqualify(String qualifiedName) { return unqualify(qualifiedName, '.'); } /** * Unqualify a string qualified by a separator character. For example, * "this:name:is:qualified" returns "qualified" if using a ':' separator. * @param qualifiedName the qualified name * @param separator the separator */ public static String unqualify(String qualifiedName, char separator) { return qualifiedName.substring(qualifiedName.lastIndexOf(separator) + 1); } /** * Capitalize a <code>String</code>, changing the first letter to * upper case as per {@link Character#toUpperCase(char)}. * No other letters are changed. * @param str the String to capitalize, may be <code>null</code> * @return the capitalized String, <code>null</code> if null */ public static String capitalize(String str) { return changeFirstCharacterCase(str, true); } /** * Uncapitalize a <code>String</code>, changing the first letter to * lower case as per {@link Character#toLowerCase(char)}. * No other letters are changed. * @param str the String to uncapitalize, may be <code>null</code> * @return the uncapitalized String, <code>null</code> if null */ public static String uncapitalize(String str) { return changeFirstCharacterCase(str, false); } private static String changeFirstCharacterCase(String str, boolean capitalize) { if (str == null || str.length() == 0) { return str; } StringBuffer buf = new StringBuffer(str.length()); if (capitalize) { buf.append(Character.toUpperCase(str.charAt(0))); } else { buf.append(Character.toLowerCase(str.charAt(0))); } buf.append(str.substring(1)); return buf.toString(); } /** * Extract the filename from the given path, * e.g. "mypath/myfile.txt" -> "myfile.txt". * @param path the file path (may be <code>null</code>) * @return the extracted filename, or <code>null</code> if none */ public static String getFilename(String path) { if (path == null) { return null; } int separatorIndex = path.lastIndexOf(FOLDER_SEPARATOR); return (separatorIndex != -1 ? path.substring(separatorIndex + 1) : path); } /** * Extract the filename extension from the given path, * e.g. "mypath/myfile.txt" -> "txt". * @param path the file path (may be <code>null</code>) * @return the extracted filename extension, or <code>null</code> if none */ public static String getFilenameExtension(String path) { if (path == null) { return null; } int sepIndex = path.lastIndexOf(EXTENSION_SEPARATOR); return (sepIndex != -1 ? path.substring(sepIndex + 1) : null); } /** * Strip the filename extension from the given path, * e.g. "mypath/myfile.txt" -> "mypath/myfile". * @param path the file path (may be <code>null</code>) * @return the path with stripped filename extension, * or <code>null</code> if none */ public static String stripFilenameExtension(String path) { if (path == null) { return null; } int sepIndex = path.lastIndexOf(EXTENSION_SEPARATOR); return (sepIndex != -1 ? path.substring(0, sepIndex) : path); } /** * Apply the given relative path to the given path, * assuming standard Java folder separation (i.e. "/" separators); * @param path the path to start from (usually a full file path) * @param relativePath the relative path to apply * (relative to the full file path above) * @return the full file path that results from applying the relative path */ public static String applyRelativePath(String path, String relativePath) { int separatorIndex = path.lastIndexOf(FOLDER_SEPARATOR); if (separatorIndex != -1) { String newPath = path.substring(0, separatorIndex); if (!relativePath.startsWith(FOLDER_SEPARATOR)) { newPath += FOLDER_SEPARATOR; } return newPath + relativePath; } else { return relativePath; } } /** * Normalize the path by suppressing sequences like "path/.." and * inner simple dots. * <p>The result is convenient for path comparison. For other uses, * notice that Windows separators ("\") are replaced by simple slashes. * @param path the original path * @return the normalized path */ public static String cleanPath(String path) { String pathToUse = replace(path, WINDOWS_FOLDER_SEPARATOR, FOLDER_SEPARATOR); // Strip prefix from path to analyze, to not treat it as part of the // first path element. This is necessary to correctly parse paths like // "file:core/../core/io/Resource.class", where the ".." should just // strip the first "core" directory while keeping the "file:" prefix. int prefixIndex = pathToUse.indexOf(":"); String prefix = ""; if (prefixIndex != -1) { prefix = pathToUse.substring(0, prefixIndex + 1); pathToUse = pathToUse.substring(prefixIndex + 1); } String[] pathArray = delimitedListToStringArray(pathToUse, FOLDER_SEPARATOR); List pathElements = new LinkedList(); int tops = 0; for (int i = pathArray.length - 1; i >= 0; i--) { if (CURRENT_PATH.equals(pathArray[i])) { // Points to current directory - drop it. } else if (TOP_PATH.equals(pathArray[i])) { // Registering top path found. tops++; } else { if (tops > 0) { // Merging path element with corresponding to top path. tops--; } else { // Normal path element found. pathElements.add(0, pathArray[i]); } } } // Remaining top paths need to be retained. for (int i = 0; i < tops; i++) { pathElements.add(0, TOP_PATH); } return prefix + collectionToDelimitedString(pathElements, FOLDER_SEPARATOR); } /** * Compare two paths after normalization of them. * @param path1 First path for comparizon * @param path2 Second path for comparizon * @return whether the two paths are equivalent after normalization */ public static boolean pathEquals(String path1, String path2) { return cleanPath(path1).equals(cleanPath(path2)); } /** * Parse the given locale string into a <code>java.util.Locale</code>. * This is the inverse operation of Locale's <code>toString</code>. * @param localeString the locale string, following * <code>java.util.Locale</code>'s toString format ("en", "en_UK", etc). * Also accepts spaces as separators, as alternative to underscores. * @return a corresponding Locale instance */ public static Locale parseLocaleString(String localeString) { String[] parts = tokenizeToStringArray(localeString, "_ ", false, false); String language = (parts.length > 0 ? parts[0] : ""); String country = (parts.length > 1 ? parts[1] : ""); String variant = (parts.length > 2 ? parts[2] : ""); return (language.length() > 0 ? new Locale(language, country, variant) : null); } //--------------------------------------------------------------------- // Convenience methods for working with String arrays //--------------------------------------------------------------------- /** * Append the given String to the given String array, returning a new array * consisting of the input array contents plus the given String. * @param array the array to append to (can be <code>null</code>) * @param str the String to append * @return the new array (never <code>null</code>) */ public static String[] addStringToArray(String[] array, String str) { if (ObjectUtils.isEmpty(array)) { return new String[] { str }; } String[] newArr = new String[array.length + 1]; System.arraycopy(array, 0, newArr, 0, array.length); newArr[array.length] = str; return newArr; } /** * Concatenate the given String arrays into one, * with overlapping array elements included twice. * <p>The order of elements in the original arrays is preserved. * @param array1 the first array (can be <code>null</code>) * @param array2 the second array (can be <code>null</code>) * @return the new array (<code>null</code> if both given arrays were <code>null</code>) */ public static String[] concatenateStringArrays(String[] array1, String[] array2) { if (ObjectUtils.isEmpty(array1)) { return array2; } if (ObjectUtils.isEmpty(array2)) { return array1; } String[] newArr = new String[array1.length + array2.length]; System.arraycopy(array1, 0, newArr, 0, array1.length); System.arraycopy(array2, 0, newArr, array1.length, array2.length); return newArr; } /** * Merge the given String arrays into one, with overlapping * array elements only included once. * <p>The order of elements in the original arrays is preserved * (with the exception of overlapping elements, which are only * included on their first occurence). * @param array1 the first array (can be <code>null</code>) * @param array2 the second array (can be <code>null</code>) * @return the new array (<code>null</code> if both given arrays were <code>null</code>) */ public static String[] mergeStringArrays(String[] array1, String[] array2) { if (ObjectUtils.isEmpty(array1)) { return array2; } if (ObjectUtils.isEmpty(array2)) { return array1; } List result = new ArrayList(); result.addAll(Arrays.asList(array1)); for (int i = 0; i < array2.length; i++) { String str = array2[i]; if (!result.contains(str)) { result.add(str); } } return toStringArray(result); } /** * Turn given source String array into sorted array. * @param array the source array * @return the sorted array (never <code>null</code>) */ public static String[] sortStringArray(String[] array) { if (ObjectUtils.isEmpty(array)) { return new String[0]; } Arrays.sort(array); return array; } /** * Copy the given Collection into a String array. * The Collection must contain String elements only. * @param collection the Collection to copy * @return the String array (<code>null</code> if the Collection * was <code>null</code> as well) */ public static String[] toStringArray(Collection collection) { if (collection == null) { return null; } return (String[]) collection.toArray(new String[collection.size()]); } /** * Remove duplicate Strings from the given array. * Also sorts the array, as it uses a TreeSet. * @param array the String array * @return an array without duplicates, in natural sort order */ public static String[] removeDuplicateStrings(String[] array) { if (ObjectUtils.isEmpty(array)) { return array; } Set set = new TreeSet(); for (int i = 0; i < array.length; i++) { set.add(array[i]); } return toStringArray(set); } /** * Split a String at the first occurrence of the delimiter. * Does not include the delimiter in the result. * @param toSplit the string to split * @param delimiter to split the string up with * @return a two element array with index 0 being before the delimiter, and * index 1 being after the delimiter (neither element includes the delimiter); * or <code>null</code> if the delimiter wasn't found in the given input String */ public static String[] split(String toSplit, String delimiter) { if (!hasLength(toSplit) || !hasLength(delimiter)) { return null; } int offset = toSplit.indexOf(delimiter); if (offset < 0) { return null; } String beforeDelimiter = toSplit.substring(0, offset); String afterDelimiter = toSplit.substring(offset + delimiter.length()); return new String[] { beforeDelimiter, afterDelimiter }; } /** * Take an array Strings and split each element based on the given delimiter. * A <code>Properties</code> instance is then generated, with the left of the * delimiter providing the key, and the right of the delimiter providing the value. * <p>Will trim both the key and value before adding them to the * <code>Properties</code> instance. * @param array the array to process * @param delimiter to split each element using (typically the equals symbol) * @return a <code>Properties</code> instance representing the array contents, * or <code>null</code> if the array to process was null or empty */ public static Properties splitArrayElementsIntoProperties(String[] array, String delimiter) { return splitArrayElementsIntoProperties(array, delimiter, null); } /** * Take an array Strings and split each element based on the given delimiter. * A <code>Properties</code> instance is then generated, with the left of the * delimiter providing the key, and the right of the delimiter providing the value. * <p>Will trim both the key and value before adding them to the * <code>Properties</code> instance. * @param array the array to process * @param delimiter to split each element using (typically the equals symbol) * @param charsToDelete one or more characters to remove from each element * prior to attempting the split operation (typically the quotation mark * symbol), or <code>null</code> if no removal should occur * @return a <code>Properties</code> instance representing the array contents, * or <code>null</code> if the array to process was null or empty */ public static Properties splitArrayElementsIntoProperties(String[] array, String delimiter, String charsToDelete) { if (array == null || array.length == 0) { return null; } Properties result = new Properties(); for (int i = 0; i < array.length; i++) { String element = array[i]; if (charsToDelete != null) { element = deleteAny(array[i], charsToDelete); } String[] splittedElement = split(element, delimiter); if (splittedElement == null) { continue; } result.setProperty(splittedElement[0].trim(), splittedElement[1].trim()); } return result; } /** * Tokenize the given String into a String array via a StringTokenizer. * Trims tokens and omits empty tokens. * <p>The given delimiters string is supposed to consist of any number of * delimiter characters. Each of those characters can be used to separate * tokens. A delimiter is always a single character; for multi-character * delimiters, consider using <code>delimitedListToStringArray</code> * @param str the String to tokenize * @param delimiters the delimiter characters, assembled as String * (each of those characters is individually considered as delimiter). * @return an array of the tokens * @see java.util.StringTokenizer * @see java.lang.String#trim * @see #delimitedListToStringArray */ public static String[] tokenizeToStringArray(String str, String delimiters) { return tokenizeToStringArray(str, delimiters, true, true); } /** * Tokenize the given String into a String array via a StringTokenizer. * <p>The given delimiters string is supposed to consist of any number of * delimiter characters. Each of those characters can be used to separate * tokens. A delimiter is always a single character; for multi-character * delimiters, consider using <code>delimitedListToStringArray</code> * @param str the String to tokenize * @param delimiters the delimiter characters, assembled as String * (each of those characters is individually considered as delimiter) * @param trimTokens trim the tokens via String's <code>trim</code> * @param ignoreEmptyTokens omit empty tokens from the result array * (only applies to tokens that are empty after trimming; StringTokenizer * will not consider subsequent delimiters as token in the first place). * @return an array of the tokens * @see java.util.StringTokenizer * @see java.lang.String#trim * @see #delimitedListToStringArray */ public static String[] tokenizeToStringArray(String str, String delimiters, boolean trimTokens, boolean ignoreEmptyTokens) { StringTokenizer st = new StringTokenizer(str, delimiters); List tokens = new ArrayList(); while (st.hasMoreTokens()) { String token = st.nextToken(); if (trimTokens) { token = token.trim(); } if (!ignoreEmptyTokens || token.length() > 0) { tokens.add(token); } } return toStringArray(tokens); } /** * Take a String which is a delimited list and convert it to a String array. * <p>A single delimiter can consists of more than one character: It will still * be considered as single delimiter string, rather than as bunch of potential * delimiter characters - in contrast to <code>tokenizeToStringArray</code>. * @param str the input String * @param delimiter the delimiter between elements (this is a single delimiter, * rather than a bunch individual delimiter characters) * @return an array of the tokens in the list * @see #tokenizeToStringArray */ public static String[] delimitedListToStringArray(String str, String delimiter) { if (str == null) { return new String[0]; } if (delimiter == null) { return new String[] { str }; } List result = new ArrayList(); if ("".equals(delimiter)) { for (int i = 0; i < str.length(); i++) { result.add(str.substring(i, i + 1)); } } else { int pos = 0; int delPos = 0; while ((delPos = str.indexOf(delimiter, pos)) != -1) { result.add(str.substring(pos, delPos)); pos = delPos + delimiter.length(); } if (str.length() > 0 && pos <= str.length()) { // Add rest of String, but not in case of empty input. result.add(str.substring(pos)); } } return toStringArray(result); } /** * Convert a CSV list into an array of Strings. * @param str CSV list * @return an array of Strings, or the empty array if s is null */ public static String[] commaDelimitedListToStringArray(String str) { return delimitedListToStringArray(str, ","); } /** * Convenience method to convert a CSV string list to a set. * Note that this will suppress duplicates. * @param str CSV String * @return a Set of String entries in the list */ public static Set commaDelimitedListToSet(String str) { Set set = new TreeSet(); String[] tokens = commaDelimitedListToStringArray(str); for (int i = 0; i < tokens.length; i++) { set.add(tokens[i]); } return set; } /** * Convenience method to return a String array as a delimited (e.g. CSV) * String. E.g. useful for toString() implementations. * @param arr array to display. Elements may be of any type (toString * will be called on each element). * @param delim delimiter to use (probably a ",") */ public static String arrayToDelimitedString(Object[] arr, String delim) { if (arr == null) { return ""; } StringBuffer sb = new StringBuffer(); for (int i = 0; i < arr.length; i++) { if (i > 0) { sb.append(delim); } sb.append(arr[i]); } return sb.toString(); } /** * Convenience method to return a Collection as a delimited (e.g. CSV) * String. E.g. useful for toString() implementations. * @param coll Collection to display * @param delim delimiter to use (probably a ",") * @param prefix string to start each element with * @param suffix string to end each element with */ public static String collectionToDelimitedString(Collection coll, String delim, String prefix, String suffix) { if (coll == null) { return ""; } StringBuffer sb = new StringBuffer(); Iterator it = coll.iterator(); int i = 0; while (it.hasNext()) { if (i > 0) { sb.append(delim); } sb.append(prefix).append(it.next()).append(suffix); i++; } return sb.toString(); } /** * Convenience method to return a Collection as a delimited (e.g. CSV) * String. E.g. useful for toString() implementations. * @param coll Collection to display * @param delim delimiter to use (probably a ",") */ public static String collectionToDelimitedString(Collection coll, String delim) { return collectionToDelimitedString(coll, delim, "", ""); } /** * Convenience method to return a String array as a CSV String. * E.g. useful for toString() implementations. * @param arr array to display. Elements may be of any type (toString * will be called on each element). */ public static String arrayToCommaDelimitedString(Object[] arr) { return arrayToDelimitedString(arr, ","); } /** * Convenience method to return a Collection as a CSV String. * E.g. useful for toString() implementations. * @param coll Collection to display */ public static String collectionToCommaDelimitedString(Collection coll) { return collectionToDelimitedString(coll, ","); } }