Java tutorial
/* * Copyright 2006-2008 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.easyjf.util; 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 // --------------------------------------------------------------------- /** * 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 (array == null || array.length < 0) 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; } /** * 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; } /** * 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 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(); } /** * 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); } 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(); } /** * 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); } /** * 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, ","); } /** * 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 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 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 (String element : tokens) set.add(element); return set; } // --------------------------------------------------------------------- // Convenience methods for working with formatted // Strings // --------------------------------------------------------------------- /** * 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, ","); } /** * 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; } /** * 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(); } /** * 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); } /** * 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); } /** * 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); } /** * 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); } /** * ?? Java ? * * @param str * ? * @return */ 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; } /** * 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); } /** * 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)); } /** * 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); } // --------------------------------------------------------------------- // Convenience methods for working with String arrays // --------------------------------------------------------------------- /** * 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 (array == null || array.length < 0) return array; Set set = new TreeSet(); for (String element : array) set.add(element); return toStringArray(set); } /** * 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(); } /** * 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 (array == null || array.length < 0) return new String[0]; Arrays.sort(array); return array; } /** * 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 (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; } /** * 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); } /** * 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); } /** * 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) { if (str == null) return new String[] {}; 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); } /** * 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()]); } /** * 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(); } /** * 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(); } /** * 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); } /** * 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); } }