Java tutorial
/* * Copyright 2015-2016 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 org.nanoframework.commons.util; import java.util.ArrayList; import java.util.Arrays; import java.util.Collection; import java.util.Collections; import java.util.Enumeration; import java.util.Iterator; import java.util.LinkedHashSet; 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.TimeZone; /** * Miscellaneous {@link String} utility methods. * * <p>Mainly for internal use within the framework; consider * <a href="http://commons.apache.org/proper/commons-lang/">Apache's Commons Lang</a> * for a more comprehensive suite of {@code String} utilities. * * <p>This class delivers some simple functionality that should really be * provided by the core Java {@link String} and {@link StringBuilder} * classes. 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 * @author Rick Evans * @author Arjen Poutsma * @author Sam Brannen * @since 16 April 2001 */ public abstract class StringUtils extends org.apache.commons.lang3.StringUtils { private static final String FOLDER_SEPARATOR = "/"; private static final char FOLDER_SEPARATOR_CHAR = '/'; 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 whether the given {@code String} is empty. * <p>This method accepts any Object as an argument, comparing it to * {@code null} and the empty String. As a consequence, this method * will never return {@code true} for a non-null non-String object. * <p>The Object signature is useful for general attribute handling code * that commonly deals with Strings but generally has to iterate over * Objects since attributes may e.g. be primitive value objects as well. * @param str the candidate String * @return Check whether the given {@code String} is empty. * @since 3.2.1 */ public static boolean isEmpty(Object str) { return (str == null || "".equals(str)); } /** * Check that the given {@code CharSequence} is neither {@code null} nor * of length 0. * Note: this method returns {@code true} for a {@code CharSequence} * that purely consists of whitespace. <br> * <pre class="code"> * StringUtils.hasLength(null) = false * StringUtils.hasLength("") = false * StringUtils.hasLength(" ") = true * StringUtils.hasLength("Hello") = true * </pre> * @param str the {@code CharSequence} to check (may be {@code null}) * @return {@code true} if the {@code CharSequence} is not {@code null} and has length * @see #hasText(String) */ public static boolean hasLength(CharSequence str) { return (str != null && str.length() > 0); } /** * Check that the given {@code String} is neither {@code null} nor of length 0.<br> * Note: this method returns {@code true} for a {@code String} that * purely consists of whitespace. * @param str the {@code String} to check (may be {@code null}) * @return {@code true} if the {@code String} is not {@code null} and has length * @see #hasLength(CharSequence) * @see #hasText(String) */ public static boolean hasLength(String str) { return hasLength((CharSequence) str); } /** * Check whether the given {@code CharSequence} contains actual <em>text</em>. * <p>More specifically, this method returns {@code true} if the * {@code CharSequence} is not {@code null}, its length is greater than * 0, and it contains at least one non-whitespace character. * <p><pre class="code"> * StringUtils.hasText(null) = false * StringUtils.hasText("") = false * StringUtils.hasText(" ") = false * StringUtils.hasText("12345") = true * StringUtils.hasText(" 12345 ") = true * </pre> * @param str the {@code CharSequence} to check (may be {@code null}) * @return {@code true} if the {@code CharSequence} is not {@code null}, * its length is greater than 0, and it does not contain whitespace only * @see Character#isWhitespace */ public static boolean hasText(CharSequence str) { if (!hasLength(str)) { return false; } int strLen = str.length(); for (int i = 0; i < strLen; i++) { if (!Character.isWhitespace(str.charAt(i))) { return true; } } return false; } /** * Check whether the given {@code String} contains actual <em>text</em>. * <p>More specifically, this method returns {@code true} if the * {@code String} is not {@code null}, its length is greater than 0, * and it contains at least one non-whitespace character. * @param str the {@code String} to check (may be {@code null}) * @return {@code true} if the {@code String} is not {@code null}, its * length is greater than 0, and it does not contain whitespace only * @see #hasText(CharSequence) */ public static boolean hasText(String str) { return hasText((CharSequence) str); } /** * Check whether the given {@code CharSequence} contains any whitespace characters. * @param str the {@code CharSequence} to check (may be {@code null}) * @return {@code true} if the {@code CharSequence} is not empty and * contains at least 1 whitespace character * @see Character#isWhitespace */ public static boolean containsWhitespace(CharSequence str) { if (!hasLength(str)) { return false; } int strLen = str.length(); for (int i = 0; i < strLen; i++) { if (Character.isWhitespace(str.charAt(i))) { return true; } } return false; } /** * Check whether the given {@code String} contains any whitespace characters. * @param str the {@code String} to check (may be {@code null}) * @return {@code true} if the {@code String} is not empty and * contains at least 1 whitespace character * @see #containsWhitespace(CharSequence) */ public static boolean containsWhitespace(String str) { return containsWhitespace((CharSequence) str); } /** * Trim leading and trailing whitespace from the given {@code String}. * @param str the {@code String} to check * @return the trimmed {@code String} * @see java.lang.Character#isWhitespace */ public static String trimWhitespace(String str) { if (!hasLength(str)) { return str; } StringBuilder sb = new StringBuilder(str); while (sb.length() > 0 && Character.isWhitespace(sb.charAt(0))) { sb.deleteCharAt(0); } while (sb.length() > 0 && Character.isWhitespace(sb.charAt(sb.length() - 1))) { sb.deleteCharAt(sb.length() - 1); } return sb.toString(); } /** * Trim <i>all</i> whitespace from the given {@code String}: * leading, trailing, and in between characters. * @param str the {@code String} to check * @return the trimmed {@code String} * @see java.lang.Character#isWhitespace */ public static String trimAllWhitespace(String str) { if (!hasLength(str)) { return str; } int len = str.length(); StringBuilder sb = new StringBuilder(str.length()); for (int i = 0; i < len; i++) { char c = str.charAt(i); if (!Character.isWhitespace(c)) { sb.append(c); } } return sb.toString(); } /** * Trim leading whitespace from the given {@code String}. * @param str the {@code String} to check * @return the trimmed {@code String} * @see java.lang.Character#isWhitespace */ public static String trimLeadingWhitespace(String str) { if (!hasLength(str)) { return str; } StringBuilder sb = new StringBuilder(str); while (sb.length() > 0 && Character.isWhitespace(sb.charAt(0))) { sb.deleteCharAt(0); } return sb.toString(); } /** * Trim trailing whitespace from the given {@code String}. * @param str the {@code String} to check * @return the trimmed {@code String} * @see java.lang.Character#isWhitespace */ public static String trimTrailingWhitespace(String str) { if (!hasLength(str)) { return str; } StringBuilder sb = new StringBuilder(str); while (sb.length() > 0 && Character.isWhitespace(sb.charAt(sb.length() - 1))) { sb.deleteCharAt(sb.length() - 1); } return sb.toString(); } /** * Trim all occurrences of the supplied leading character from the given {@code String}. * @param str the {@code String} to check * @param leadingCharacter the leading character to be trimmed * @return the trimmed {@code String} */ public static String trimLeadingCharacter(String str, char leadingCharacter) { if (!hasLength(str)) { return str; } StringBuilder sb = new StringBuilder(str); while (sb.length() > 0 && sb.charAt(0) == leadingCharacter) { sb.deleteCharAt(0); } return sb.toString(); } /** * Trim all occurrences of the supplied trailing character from the given {@code String}. * @param str the {@code String} to check * @param trailingCharacter the trailing character to be trimmed * @return the trimmed {@code String} */ public static String trimTrailingCharacter(String str, char trailingCharacter) { if (!hasLength(str)) { return str; } StringBuilder sb = new StringBuilder(str); while (sb.length() > 0 && sb.charAt(sb.length() - 1) == trailingCharacter) { sb.deleteCharAt(sb.length() - 1); } return sb.toString(); } /** * Test if the given {@code String} starts with the specified prefix, * ignoring upper/lower case. * @param str the {@code String} to check * @param prefix the prefix to look for * @return Test if the given {@code String} starts with the specified prefix, * ignoring upper/lower case. * @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 {@code String} ends with the specified suffix, * ignoring upper/lower case. * @param str the {@code String} to check * @param suffix the suffix to look for * @return Test if the given {@code String} ends with the specified suffix, * ignoring upper/lower case. * @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); } /** * Test whether the given string matches the given substring * at the given index. * @param str the original string (or StringBuilder) * @param index the index in the original string to start matching against * @param substring the substring to match at the given index * @return Test whether the given string matches the given substring * at the given index. */ public static boolean substringMatch(CharSequence str, int index, CharSequence substring) { for (int j = 0; j < substring.length(); j++) { int i = index + j; if (i >= str.length() || str.charAt(i) != substring.charAt(j)) { return false; } } return true; } /** * Count the occurrences of the substring {@code sub} in string {@code str}. * @param str string to search in. Return 0 if this is {@code null}. * @param sub string to search for. Return 0 if this is {@code null}. * @return Count the occurrences of the substring {@code sub} in string {@code str}. */ public static int countOccurrencesOf(String str, String sub) { if (str == null || sub == null || str.length() == 0 || sub.length() == 0) { return 0; } int count = 0; int pos = 0; int idx; while ((idx = str.indexOf(sub, pos)) != -1) { ++count; pos = idx + sub.length(); } return count; } /** * Replace all occurrences of a substring within a string with * another string. * @param inString {@code String} to examine * @param oldPattern {@code String} to replace * @param newPattern {@code String} to insert * @return a {@code String} with the replacements */ public static String replace(String inString, String oldPattern, String newPattern) { if (!hasLength(inString) || !hasLength(oldPattern) || newPattern == null) { return inString; } StringBuilder sb = new StringBuilder(); 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) { sb.append(inString.substring(pos, index)); sb.append(newPattern); pos = index + patLen; index = inString.indexOf(oldPattern, pos); } sb.append(inString.substring(pos)); // remember to append any characters to the right of a match return sb.toString(); } /** * Delete all occurrences of the given substring. * @param inString the original {@code String} * @param pattern the pattern to delete all occurrences of * @return the resulting {@code String} */ public static String delete(String inString, String pattern) { return replace(inString, pattern, ""); } /** * Delete any character in a given {@code String}. * @param inString the original {@code String} * @param charsToDelete a set of characters to delete. * E.g. "az\n" will delete 'a's, 'z's and new lines. * @return the resulting {@code String} */ public static String deleteAny(String inString, String charsToDelete) { if (!hasLength(inString) || !hasLength(charsToDelete)) { return inString; } StringBuilder sb = new StringBuilder(); for (int i = 0; i < inString.length(); i++) { char c = inString.charAt(i); if (charsToDelete.indexOf(c) == -1) { sb.append(c); } } return sb.toString(); } //--------------------------------------------------------------------- // Convenience methods for working with formatted Strings //--------------------------------------------------------------------- /** * Quote the given {@code String} with single quotes. * @param str the input {@code String} (e.g. "myString") * @return the quoted {@code String} (e.g. "'myString'"), * or {@code null} if the input was {@code null} */ public static String quote(String str) { return (str != null ? '\'' + str + '\'' : null); } /** * Turn the given Object into a {@code String} with single quotes * if it is a {@code String}; keeping the Object as-is else. * @param obj the input Object (e.g. "myString") * @return the quoted {@code String} (e.g. "'myString'"), * or the input object as-is if not a {@code 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 * @return Unqualify a string qualified by a '.' dot character. For example, * "this.name.is.qualified", returns "qualified". */ 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 * @return Unqualify a string qualified by a separator character. For example, * "this:name:is:qualified" returns "qualified" if using a ':' separator. */ public static String unqualify(String qualifiedName, char separator) { return qualifiedName.substring(qualifiedName.lastIndexOf(separator) + 1); } /** * Capitalize a {@code String}, changing the first letter to * upper case as per {@link Character#toUpperCase(char)}. * No other letters are changed. * @param str the {@code String} to capitalize, may be {@code null} * @return the capitalized {@code String}, or {@code null} if the supplied * string is {@code null} */ public static String capitalize(String str) { return changeFirstCharacterCase(str, true); } /** * Uncapitalize a {@code String}, changing the first letter to * lower case as per {@link Character#toLowerCase(char)}. * No other letters are changed. * @param str the {@code String} to uncapitalize, may be {@code null} * @return the uncapitalized {@code String}, or {@code null} if the supplied * string is {@code 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; } StringBuilder sb = new StringBuilder(str.length()); if (capitalize) { sb.append(Character.toUpperCase(str.charAt(0))); } else { sb.append(Character.toLowerCase(str.charAt(0))); } sb.append(str.substring(1)); return sb.toString(); } /** * Extract the filename from the given path, * e.g. {@code "mypath/myfile.txt" -> "myfile.txt"}. * @param path the file path (may be {@code null}) * @return the extracted filename, or {@code null} if none */ public static String getFilename(String path) { if (path == null) { return null; } int separatorIndex = path.lastIndexOf(FOLDER_SEPARATOR_CHAR); 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}) * @return the extracted filename extension, or {@code null} if none */ public static String getFilenameExtension(String path) { if (path == null) { return null; } int extIndex = path.lastIndexOf(EXTENSION_SEPARATOR); if (extIndex == -1) { return null; } int folderIndex = path.lastIndexOf(FOLDER_SEPARATOR_CHAR); if (folderIndex > extIndex) { return null; } return path.substring(extIndex + 1); } /** * Strip the filename extension from the given path, * e.g. "mypath/myfile.txt" -> "mypath/myfile". * @param path the file path (may be {@code null}) * @return the path with stripped filename extension, * or {@code null} if none */ public static String stripFilenameExtension(String path) { if (path == null) { return null; } int extIndex = path.lastIndexOf(EXTENSION_SEPARATOR); if (extIndex == -1) { return path; } int folderIndex = path.lastIndexOf(FOLDER_SEPARATOR_CHAR); if (folderIndex > extIndex) { return path; } return path.substring(0, extIndex); } /** * 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_CHAR); if (separatorIndex != -1) { String newPath = path.substring(0, separatorIndex); if (!relativePath.startsWith(FOLDER_SEPARATOR)) { newPath += FOLDER_SEPARATOR_CHAR; } 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) { if (path == null) { return null; } 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); if (prefix.contains("/")) { prefix = ""; } else { pathToUse = pathToUse.substring(prefixIndex + 1); } } if (pathToUse.startsWith(FOLDER_SEPARATOR)) { prefix = prefix + FOLDER_SEPARATOR_CHAR; pathToUse = pathToUse.substring(1); } String[] pathArray = delimitedListToStringArray(pathToUse, FOLDER_SEPARATOR); List<String> pathElements = new LinkedList<String>(); int tops = 0; for (int i = pathArray.length - 1; i >= 0; i--) { String element = pathArray[i]; if (CURRENT_PATH.equals(element)) { // Points to current directory - drop it. } else if (TOP_PATH.equals(element)) { // Registering top path found. tops++; } else { if (tops > 0) { // Merging path element with element corresponding to top path. tops--; } else { // Normal path element found. pathElements.add(0, element); } } } // 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 comparison * @param path2 second path for comparison * @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 {@code localeString} value into a {@link Locale}. * <p>This is the inverse operation of {@link Locale#toString Locale's toString}. * @param localeString the locale {@code String}, following {@code Locale's} * {@code toString()} format ("en", "en_UK", etc); * also accepts spaces as separators, as an alternative to underscores * @return a corresponding {@code Locale} instance * @throws IllegalArgumentException in case of an invalid locale specification */ 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] : ""); validateLocalePart(language); validateLocalePart(country); String variant = ""; if (parts.length > 2) { // There is definitely a variant, and it is everything after the country // code sans the separator between the country code and the variant. int endIndexOfCountryCode = localeString.indexOf(country, language.length()) + country.length(); // Strip off any leading '_' and whitespace, what's left is the variant. variant = trimLeadingWhitespace(localeString.substring(endIndexOfCountryCode)); if (variant.startsWith("_")) { variant = trimLeadingCharacter(variant, '_'); } } return (language.length() > 0 ? new Locale(language, country, variant) : null); } private static void validateLocalePart(String localePart) { for (int i = 0; i < localePart.length(); i++) { char ch = localePart.charAt(i); if (ch != '_' && ch != ' ' && !Character.isLetterOrDigit(ch)) { throw new IllegalArgumentException( "Locale part \"" + localePart + "\" contains invalid characters"); } } } /** * Determine the RFC 3066 compliant language tag, * as used for the HTTP "Accept-Language" header. * @param locale the Locale to transform to a language tag * @return the RFC 3066 compliant language tag as {@code String} */ public static String toLanguageTag(Locale locale) { return locale.getLanguage() + (hasText(locale.getCountry()) ? '-' + locale.getCountry() : ""); } /** * Parse the given {@code timeZoneString} value into a {@link TimeZone}. * @param timeZoneString the time zone {@code String}, following {@link TimeZone#getTimeZone(String)} * but throwing {@link IllegalArgumentException} in case of an invalid time zone specification * @return a corresponding {@link TimeZone} instance * @throws IllegalArgumentException in case of an invalid time zone specification */ public static TimeZone parseTimeZoneString(String timeZoneString) { TimeZone timeZone = TimeZone.getTimeZone(timeZoneString); if ("GMT".equals(timeZone.getID()) && !timeZoneString.startsWith("GMT")) { // We don't want that GMT fallback... throw new IllegalArgumentException("Invalid time zone specification '" + timeZoneString + '\''); } return timeZone; } //--------------------------------------------------------------------- // Convenience methods for working with String arrays //--------------------------------------------------------------------- /** * Append the given {@code String} to the given {@code String} array, * returning a new array consisting of the input array contents plus * the given {@code String}. * @param array the array to append to (can be {@code null}) * @param str the {@code String} to append * @return the new array (never {@code null}) */ 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 {@code 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}) * @param array2 the second array (can be {@code null}) * @return the new array ({@code null} if both given arrays were {@code null}) */ 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 {@code 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 occurrence). * @param array1 the first array (can be {@code null}) * @param array2 the second array (can be {@code null}) * @return the new array ({@code null} if both given arrays were {@code null}) */ public static String[] mergeStringArrays(String[] array1, String[] array2) { if (ObjectUtils.isEmpty(array1)) { return array2; } if (ObjectUtils.isEmpty(array2)) { return array1; } List<String> result = new ArrayList<String>(); result.addAll(Arrays.asList(array1)); for (String str : array2) { if (!result.contains(str)) { result.add(str); } } return toStringArray(result); } /** * Turn given source {@code String} array into sorted array. * @param array the source array * @return the sorted array (never {@code null}) */ public static String[] sortStringArray(String[] array) { if (ObjectUtils.isEmpty(array)) { return new String[0]; } Arrays.sort(array); return array; } /** * Copy the given {@code Collection} into a {@code String} array. * <p>The {@code Collection} must contain {@code String} elements only. * @param collection the {@code Collection} to copy * @return the {@code String} array ({@code null} if the supplied * {@code Collection} was {@code null}) */ public static String[] toStringArray(Collection<String> collection) { if (collection == null) { return null; } return collection.toArray(new String[collection.size()]); } /** * Copy the given Enumeration into a {@code String} array. * The Enumeration must contain {@code String} elements only. * @param enumeration the Enumeration to copy * @return the {@code String} array ({@code null} if the passed-in * Enumeration was {@code null}) */ public static String[] toStringArray(Enumeration<String> enumeration) { if (enumeration == null) { return null; } List<String> list = Collections.list(enumeration); return list.toArray(new String[list.size()]); } /** * Trim the elements of the given {@code String} array, * calling {@code String.trim()} on each of them. * @param array the original {@code String} array * @return the resulting array (of the same size) with trimmed elements */ public static String[] trimArrayElements(String[] array) { if (ObjectUtils.isEmpty(array)) { return new String[0]; } String[] result = new String[array.length]; for (int i = 0; i < array.length; i++) { String element = array[i]; result[i] = (element != null ? element.trim() : null); } return result; } /** * Remove duplicate strings from the given array. * <p>As of 4.2, it preserves the original order, as it uses a {@link LinkedHashSet}. * @param array the {@code String} array * @return an array without duplicates, in natural sort order */ public static String[] removeDuplicateStrings(String[] array) { if (ObjectUtils.isEmpty(array)) { return array; } Set<String> set = new LinkedHashSet<String>(); for (String element : array) { set.add(element); } return toStringArray(set); } /** * Split a {@code 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} if the delimiter wasn't found in the given input {@code 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 of strings and split each element based on the given delimiter. * A {@code Properties} 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} instance. * @param array the array to process * @param delimiter to split each element using (typically the equals symbol) * @return a {@code Properties} instance representing the array contents, * or {@code null} if the array to process was {@code null} or empty */ public static Properties splitArrayElementsIntoProperties(String[] array, String delimiter) { return splitArrayElementsIntoProperties(array, delimiter, null); } /** * Take an array of strings and split each element based on the given delimiter. * A {@code Properties} 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} 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} if no removal should occur * @return a {@code Properties} instance representing the array contents, * or {@code null} if the array to process was {@code null} or empty */ public static Properties splitArrayElementsIntoProperties(String[] array, String delimiter, String charsToDelete) { if (ObjectUtils.isEmpty(array)) { return null; } Properties result = new Properties(); for (String element : array) { if (charsToDelete != null) { element = deleteAny(element, charsToDelete); } String[] splittedElement = split(element, delimiter); if (splittedElement == null) { continue; } result.setProperty(splittedElement[0].trim(), splittedElement[1].trim()); } return result; } /** * Tokenize the given {@code String} into a {@code String} array via a * {@link StringTokenizer}. * <p>Trims tokens and omits empty tokens. * <p>The given {@code delimiters} string can 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 {@link #delimitedListToStringArray}. * @param str the {@code String} to tokenize * @param delimiters the delimiter characters, assembled as a {@code String} * (each of the characters is individually considered as a delimiter) * @return an array of the tokens * @see java.util.StringTokenizer * @see String#trim() * @see #delimitedListToStringArray */ public static String[] tokenizeToStringArray(String str, String delimiters) { return tokenizeToStringArray(str, delimiters, true, true); } /** * Tokenize the given {@code String} into a {@code String} array via a * {@link StringTokenizer}. * <p>The given {@code delimiters} string can 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 {@link #delimitedListToStringArray}. * @param str the {@code String} to tokenize * @param delimiters the delimiter characters, assembled as a {@code String} * (each of the characters is individually considered as a delimiter) * @param trimTokens trim the tokens via {@link String#trim()} * @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 ({@code null} if the input {@code String} * was {@code null}) * @see java.util.StringTokenizer * @see String#trim() * @see #delimitedListToStringArray */ public static String[] tokenizeToStringArray(String str, String delimiters, boolean trimTokens, boolean ignoreEmptyTokens) { if (str == null) { return null; } StringTokenizer st = new StringTokenizer(str, delimiters); List<String> tokens = new ArrayList<String>(); 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 {@code String} that is a delimited list and convert it into a * {@code String} array. * <p>A single {@code delimiter} may consist of more than one character, * but it will still be considered as a single delimiter string, rather * than as bunch of potential delimiter characters, in contrast to * {@link #tokenizeToStringArray}. * @param str the input {@code 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) { return delimitedListToStringArray(str, delimiter, null); } /** * Take a {@code String} that is a delimited list and convert it into * a {@code String} array. * <p>A single {@code delimiter} may consist of more than one character, * but it will still be considered as a single delimiter string, rather * than as bunch of potential delimiter characters, in contrast to * {@link #tokenizeToStringArray}. * @param str the input {@code String} * @param delimiter the delimiter between elements (this is a single delimiter, * rather than a bunch individual delimiter characters) * @param charsToDelete a set of characters to delete; useful for deleting unwanted * line breaks: e.g. "\r\n\f" will delete all new lines and line feeds in a {@code String} * @return an array of the tokens in the list * @see #tokenizeToStringArray */ public static String[] delimitedListToStringArray(String str, String delimiter, String charsToDelete) { if (str == null) { return new String[0]; } if (delimiter == null) { return new String[] { str }; } List<String> result = new ArrayList<String>(); if ("".equals(delimiter)) { for (int i = 0; i < str.length(); i++) { result.add(deleteAny(str.substring(i, i + 1), charsToDelete)); } } else { int pos = 0; int delPos; while ((delPos = str.indexOf(delimiter, pos)) != -1) { result.add(deleteAny(str.substring(pos, delPos), charsToDelete)); pos = delPos + delimiter.length(); } if (str.length() > 0 && pos <= str.length()) { // Add rest of String, but not in case of empty input. result.add(deleteAny(str.substring(pos), charsToDelete)); } } return toStringArray(result); } /** * Convert a comma delimited list (e.g., a row from a CSV file) into an * array of strings. * @param str the input {@code String} * @return an array of strings, or the empty array in case of empty input */ public static String[] commaDelimitedListToStringArray(String str) { return delimitedListToStringArray(str, ","); } /** * Convert a comma delimited list (e.g., a row from a CSV file) into a set. * <p>Note that this will suppress duplicates, and as of 4.2, the elements in * the returned set will preserve the original order in a {@link LinkedHashSet}. * @param str the input {@code String} * @return a set of {@code String} entries in the list * @see #removeDuplicateStrings(String[]) */ public static Set<String> commaDelimitedListToSet(String str) { Set<String> set = new LinkedHashSet<String>(); String[] tokens = commaDelimitedListToStringArray(str); for (String token : tokens) { set.add(token); } return set; } /** * Convert a {@link Collection} to a delimited {@code String} (e.g. CSV). * <p>Useful for {@code toString()} implementations. * @param coll the {@code Collection} to convert * @param delim the delimiter to use (typically a ",") * @param prefix the {@code String} to start each element with * @param suffix the {@code String} to end each element with * @return the delimited {@code String} */ public static String collectionToDelimitedString(Collection<?> coll, String delim, String prefix, String suffix) { if (CollectionUtils.isEmpty(coll)) { return ""; } StringBuilder sb = new StringBuilder(); Iterator<?> it = coll.iterator(); while (it.hasNext()) { sb.append(prefix).append(it.next()).append(suffix); if (it.hasNext()) { sb.append(delim); } } return sb.toString(); } /** * Convert a {@code Collection} into a delimited {@code String} (e.g. CSV). * <p>Useful for {@code toString()} implementations. * @param coll the {@code Collection} to convert * @param delim the delimiter to use (typically a ",") * @return the delimited {@code String} */ public static String collectionToDelimitedString(Collection<?> coll, String delim) { return collectionToDelimitedString(coll, delim, "", ""); } /** * Convert a {@code Collection} into a delimited {@code String} (e.g., CSV). * <p>Useful for {@code toString()} implementations. * @param coll the {@code Collection} to convert * @return the delimited {@code String} */ public static String collectionToCommaDelimitedString(Collection<?> coll) { return collectionToDelimitedString(coll, ","); } /** * Convert a {@code String} array into a delimited {@code String} (e.g. CSV). * <p>Useful for {@code toString()} implementations. * @param arr the array to display * @param delim the delimiter to use (typically a ",") * @return the delimited {@code String} */ public static String arrayToDelimitedString(Object[] arr, String delim) { if (ObjectUtils.isEmpty(arr)) { return ""; } if (arr.length == 1) { return ObjectUtils.nullSafeToString(arr[0]); } StringBuilder sb = new StringBuilder(); for (int i = 0; i < arr.length; i++) { if (i > 0) { sb.append(delim); } sb.append(arr[i]); } return sb.toString(); } /** * Convert a {@code String} array into a comma delimited {@code String} * (i.e., CSV). * <p>Useful for {@code toString()} implementations. * @param arr the array to display * @return the delimited {@code String} */ public static String arrayToCommaDelimitedString(Object[] arr) { return arrayToDelimitedString(arr, ","); } /** * <p>Converts a String to a boolean (optimised for performance).</p> * * <p>{@code 'true'}, {@code 'on'}, {@code 'y'}, {@code 't'} or {@code 'yes'} * (case insensitive) will return {@code true}. Otherwise, * {@code false} is returned.</p> * * <p>This method performs 4 times faster (JDK1.4) than * {@code Boolean.valueOf(String)}. However, this method accepts * 'on' and 'yes', 't', 'y' as true values. * * <pre> * BooleanUtils.toBoolean(null) = false * BooleanUtils.toBoolean("true") = true * BooleanUtils.toBoolean("TRUE") = true * BooleanUtils.toBoolean("tRUe") = true * BooleanUtils.toBoolean("on") = true * BooleanUtils.toBoolean("yes") = true * BooleanUtils.toBoolean("false") = false * BooleanUtils.toBoolean("x gti") = false * BooleanUtils.toBooleanObject("y") = true * BooleanUtils.toBooleanObject("n") = false * BooleanUtils.toBooleanObject("t") = true * BooleanUtils.toBooleanObject("f") = false * </pre> * * @param str the String to check * @return the boolean value of the string, {@code false} if no match or the String is null */ public static boolean toBoolean(final String str) { return toBooleanObject(str) == Boolean.TRUE; } /** * <p>Converts a String to a Boolean.</p> * * <p>{@code 'true'}, {@code 'on'}, {@code 'y'}, {@code 't'} or {@code 'yes'} * (case insensitive) will return {@code true}. * {@code 'false'}, {@code 'off'}, {@code 'n'}, {@code 'f'} or {@code 'no'} * (case insensitive) will return {@code false}. * Otherwise, {@code null} is returned.</p> * * <p>NOTE: This returns null and will throw a NullPointerException if autoboxed to a boolean. </p> * * <pre> * // N.B. case is not significant * BooleanUtils.toBooleanObject(null) = null * BooleanUtils.toBooleanObject("true") = Boolean.TRUE * BooleanUtils.toBooleanObject("T") = Boolean.TRUE // i.e. T[RUE] * BooleanUtils.toBooleanObject("false") = Boolean.FALSE * BooleanUtils.toBooleanObject("f") = Boolean.FALSE // i.e. f[alse] * BooleanUtils.toBooleanObject("No") = Boolean.FALSE * BooleanUtils.toBooleanObject("n") = Boolean.FALSE // i.e. n[o] * BooleanUtils.toBooleanObject("on") = Boolean.TRUE * BooleanUtils.toBooleanObject("ON") = Boolean.TRUE * BooleanUtils.toBooleanObject("off") = Boolean.FALSE * BooleanUtils.toBooleanObject("oFf") = Boolean.FALSE * BooleanUtils.toBooleanObject("yes") = Boolean.TRUE * BooleanUtils.toBooleanObject("Y") = Boolean.TRUE // i.e. Y[ES] * BooleanUtils.toBooleanObject("blue") = null * BooleanUtils.toBooleanObject("true ") = null // trailing space (too long) * BooleanUtils.toBooleanObject("ono") = null // does not match on or no * </pre> * * @param str the String to check; upper and lower case are treated as the same * @return the Boolean value of the string, {@code null} if no match or {@code null} input */ public static Boolean toBooleanObject(final String str) { // Previously used equalsIgnoreCase, which was fast for interned 'true'. // Non interned 'true' matched 15 times slower. // // Optimisation provides same performance as before for interned 'true'. // Similar performance for null, 'false', and other strings not length 2/3/4. // 'true'/'TRUE' match 4 times slower, 'tRUE'/'True' 7 times slower. if ("true".equals(str)) { return Boolean.TRUE; } if (str == null) { return null; } switch (str.length()) { case 1: { final char ch0 = str.charAt(0); if (ch0 == 'y' || ch0 == 'Y' || ch0 == 't' || ch0 == 'T') { return Boolean.TRUE; } if (ch0 == 'n' || ch0 == 'N' || ch0 == 'f' || ch0 == 'F') { return Boolean.FALSE; } break; } case 2: { final char ch0 = str.charAt(0); final char ch1 = str.charAt(1); if ((ch0 == 'o' || ch0 == 'O') && (ch1 == 'n' || ch1 == 'N')) { return Boolean.TRUE; } if ((ch0 == 'n' || ch0 == 'N') && (ch1 == 'o' || ch1 == 'O')) { return Boolean.FALSE; } break; } case 3: { final char ch0 = str.charAt(0); final char ch1 = str.charAt(1); final char ch2 = str.charAt(2); if ((ch0 == 'y' || ch0 == 'Y') && (ch1 == 'e' || ch1 == 'E') && (ch2 == 's' || ch2 == 'S')) { return Boolean.TRUE; } if ((ch0 == 'o' || ch0 == 'O') && (ch1 == 'f' || ch1 == 'F') && (ch2 == 'f' || ch2 == 'F')) { return Boolean.FALSE; } break; } case 4: { final char ch0 = str.charAt(0); final char ch1 = str.charAt(1); final char ch2 = str.charAt(2); final char ch3 = str.charAt(3); if ((ch0 == 't' || ch0 == 'T') && (ch1 == 'r' || ch1 == 'R') && (ch2 == 'u' || ch2 == 'U') && (ch3 == 'e' || ch3 == 'E')) { return Boolean.TRUE; } break; } case 5: { final char ch0 = str.charAt(0); final char ch1 = str.charAt(1); final char ch2 = str.charAt(2); final char ch3 = str.charAt(3); final char ch4 = str.charAt(4); if ((ch0 == 'f' || ch0 == 'F') && (ch1 == 'a' || ch1 == 'A') && (ch2 == 'l' || ch2 == 'L') && (ch3 == 's' || ch3 == 'S') && (ch4 == 'e' || ch4 == 'E')) { return Boolean.FALSE; } break; } default: break; } return null; } /** * <p>Convert a <code>String</code> to a <code>long</code>, returning a * default value if the conversion fails.</p> * * <p>If the string is <code>null</code>, the default value is returned.</p> * * <pre> * NumberUtils.toLong(null, 1L) = 1L * NumberUtils.toLong("", 1L) = 1L * NumberUtils.toLong("1", 0L) = 1L * </pre> * * @param str the string to convert, may be null * @param defaultValue the default value * @return the long represented by the string, or the default if conversion fails */ public static long toLong(final String str, final long defaultValue) { if (str == null) { return defaultValue; } try { return Long.parseLong(str); } catch (final NumberFormatException nfe) { return defaultValue; } } /** * <p>Convert a <code>String</code> to an <code>int</code>, returning a * default value if the conversion fails.</p> * * <p>If the string is <code>null</code>, the default value is returned.</p> * * <pre> * NumberUtils.toInt(null, 1) = 1 * NumberUtils.toInt("", 1) = 1 * NumberUtils.toInt("1", 0) = 1 * </pre> * * @param str the string to convert, may be null * @param defaultValue the default value * @return the int represented by the string, or the default if conversion fails */ public static int toInt(final String str, final int defaultValue) { if (str == null) { return defaultValue; } try { return Integer.parseInt(str); } catch (final NumberFormatException nfe) { return defaultValue; } } }