Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * 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.apache.commons.lang3; import java.util.regex.Pattern; /** * <p>Helpers to process Strings using regular expressions.</p> * @see java.util.regex.Pattern * @since 3.8 */ public class RegExUtils { /** * <p>Removes each substring of the text String that matches the given regular expression pattern.</p> * * This method is a {@code null} safe equivalent to: * <ul> * <li>{@code pattern.matcher(text).replaceAll(StringUtils.EMPTY)}</li> * </ul> * * <p>A {@code null} reference passed to this method is a no-op.</p> * * <pre> * StringUtils.removeAll(null, *) = null * StringUtils.removeAll("any", (Pattern) null) = "any" * StringUtils.removeAll("any", Pattern.compile("")) = "any" * StringUtils.removeAll("any", Pattern.compile(".*")) = "" * StringUtils.removeAll("any", Pattern.compile(".+")) = "" * StringUtils.removeAll("abc", Pattern.compile(".?")) = "" * StringUtils.removeAll("A<__>\n<__>B", Pattern.compile("<.*>")) = "A\nB" * StringUtils.removeAll("A<__>\n<__>B", Pattern.compile("(?s)<.*>")) = "AB" * StringUtils.removeAll("A<__>\n<__>B", Pattern.compile("<.*>", Pattern.DOTALL)) = "AB" * StringUtils.removeAll("ABCabc123abc", Pattern.compile("[a-z]")) = "ABC123" * </pre> * * @param text text to remove from, may be null * @param regex the regular expression to which this string is to be matched * @return the text with any removes processed, * {@code null} if null String input * * @see #replaceAll(String, Pattern, String) * @see java.util.regex.Matcher#replaceAll(String) * @see java.util.regex.Pattern */ public static String removeAll(final String text, final Pattern regex) { return replaceAll(text, regex, StringUtils.EMPTY); } /** * <p>Removes each substring of the text String that matches the given regular expression.</p> * * This method is a {@code null} safe equivalent to: * <ul> * <li>{@code text.replaceAll(regex, StringUtils.EMPTY)}</li> * <li>{@code Pattern.compile(regex).matcher(text).replaceAll(StringUtils.EMPTY)}</li> * </ul> * * <p>A {@code null} reference passed to this method is a no-op.</p> * * <p>Unlike in the {@link #removePattern(String, String)} method, the {@link Pattern#DOTALL} option * is NOT automatically added. * To use the DOTALL option prepend <code>"(?s)"</code> to the regex. * DOTALL is also known as single-line mode in Perl.</p> * * <pre> * StringUtils.removeAll(null, *) = null * StringUtils.removeAll("any", (String) null) = "any" * StringUtils.removeAll("any", "") = "any" * StringUtils.removeAll("any", ".*") = "" * StringUtils.removeAll("any", ".+") = "" * StringUtils.removeAll("abc", ".?") = "" * StringUtils.removeAll("A<__>\n<__>B", "<.*>") = "A\nB" * StringUtils.removeAll("A<__>\n<__>B", "(?s)<.*>") = "AB" * StringUtils.removeAll("ABCabc123abc", "[a-z]") = "ABC123" * </pre> * * @param text text to remove from, may be null * @param regex the regular expression to which this string is to be matched * @return the text with any removes processed, * {@code null} if null String input * * @throws java.util.regex.PatternSyntaxException * if the regular expression's syntax is invalid * * @see #replaceAll(String, String, String) * @see #removePattern(String, String) * @see String#replaceAll(String, String) * @see java.util.regex.Pattern * @see java.util.regex.Pattern#DOTALL */ public static String removeAll(final String text, final String regex) { return replaceAll(text, regex, StringUtils.EMPTY); } /** * <p>Removes the first substring of the text string that matches the given regular expression pattern.</p> * * This method is a {@code null} safe equivalent to: * <ul> * <li>{@code pattern.matcher(text).replaceFirst(StringUtils.EMPTY)}</li> * </ul> * * <p>A {@code null} reference passed to this method is a no-op.</p> * * <pre> * StringUtils.removeFirst(null, *) = null * StringUtils.removeFirst("any", (Pattern) null) = "any" * StringUtils.removeFirst("any", Pattern.compile("")) = "any" * StringUtils.removeFirst("any", Pattern.compile(".*")) = "" * StringUtils.removeFirst("any", Pattern.compile(".+")) = "" * StringUtils.removeFirst("abc", Pattern.compile(".?")) = "bc" * StringUtils.removeFirst("A<__>\n<__>B", Pattern.compile("<.*>")) = "A\n<__>B" * StringUtils.removeFirst("A<__>\n<__>B", Pattern.compile("(?s)<.*>")) = "AB" * StringUtils.removeFirst("ABCabc123", Pattern.compile("[a-z]")) = "ABCbc123" * StringUtils.removeFirst("ABCabc123abc", Pattern.compile("[a-z]+")) = "ABC123abc" * </pre> * * @param text text to remove from, may be null * @param regex the regular expression pattern to which this string is to be matched * @return the text with the first replacement processed, * {@code null} if null String input * * @see #replaceFirst(String, Pattern, String) * @see java.util.regex.Matcher#replaceFirst(String) * @see java.util.regex.Pattern */ public static String removeFirst(final String text, final Pattern regex) { return replaceFirst(text, regex, StringUtils.EMPTY); } /** * <p>Removes the first substring of the text string that matches the given regular expression.</p> * * This method is a {@code null} safe equivalent to: * <ul> * <li>{@code text.replaceFirst(regex, StringUtils.EMPTY)}</li> * <li>{@code Pattern.compile(regex).matcher(text).replaceFirst(StringUtils.EMPTY)}</li> * </ul> * * <p>A {@code null} reference passed to this method is a no-op.</p> * * <p>The {@link Pattern#DOTALL} option is NOT automatically added. * To use the DOTALL option prepend <code>"(?s)"</code> to the regex. * DOTALL is also known as single-line mode in Perl.</p> * * <pre> * StringUtils.removeFirst(null, *) = null * StringUtils.removeFirst("any", (String) null) = "any" * StringUtils.removeFirst("any", "") = "any" * StringUtils.removeFirst("any", ".*") = "" * StringUtils.removeFirst("any", ".+") = "" * StringUtils.removeFirst("abc", ".?") = "bc" * StringUtils.removeFirst("A<__>\n<__>B", "<.*>") = "A\n<__>B" * StringUtils.removeFirst("A<__>\n<__>B", "(?s)<.*>") = "AB" * StringUtils.removeFirst("ABCabc123", "[a-z]") = "ABCbc123" * StringUtils.removeFirst("ABCabc123abc", "[a-z]+") = "ABC123abc" * </pre> * * @param text text to remove from, may be null * @param regex the regular expression to which this string is to be matched * @return the text with the first replacement processed, * {@code null} if null String input * * @throws java.util.regex.PatternSyntaxException * if the regular expression's syntax is invalid * * @see #replaceFirst(String, String, String) * @see String#replaceFirst(String, String) * @see java.util.regex.Pattern * @see java.util.regex.Pattern#DOTALL */ public static String removeFirst(final String text, final String regex) { return replaceFirst(text, regex, StringUtils.EMPTY); } /** * <p>Removes each substring of the source String that matches the given regular expression using the DOTALL option.</p> * * This call is a {@code null} safe equivalent to: * <ul> * <li>{@code text.replaceAll("(?s)" + regex, StringUtils.EMPTY)}</li> * <li>{@code Pattern.compile(regex, Pattern.DOTALL).matcher(text).replaceAll(StringUtils.EMPTY)}</li> * </ul> * * <p>A {@code null} reference passed to this method is a no-op.</p> * * <pre> * StringUtils.removePattern(null, *) = null * StringUtils.removePattern("any", (String) null) = "any" * StringUtils.removePattern("A<__>\n<__>B", "<.*>") = "AB" * StringUtils.removePattern("ABCabc123", "[a-z]") = "ABC123" * </pre> * * @param text * the source string * @param regex * the regular expression to which this string is to be matched * @return The resulting {@code String} * @see #replacePattern(String, String, String) * @see String#replaceAll(String, String) * @see Pattern#DOTALL */ public static String removePattern(final String text, final String regex) { return replacePattern(text, regex, StringUtils.EMPTY); } /** * <p>Replaces each substring of the text String that matches the given regular expression pattern with the given replacement.</p> * * This method is a {@code null} safe equivalent to: * <ul> * <li>{@code pattern.matcher(text).replaceAll(replacement)}</li> * </ul> * * <p>A {@code null} reference passed to this method is a no-op.</p> * * <pre> * StringUtils.replaceAll(null, *, *) = null * StringUtils.replaceAll("any", (Pattern) null, *) = "any" * StringUtils.replaceAll("any", *, null) = "any" * StringUtils.replaceAll("", Pattern.compile(""), "zzz") = "zzz" * StringUtils.replaceAll("", Pattern.compile(".*"), "zzz") = "zzz" * StringUtils.replaceAll("", Pattern.compile(".+"), "zzz") = "" * StringUtils.replaceAll("abc", Pattern.compile(""), "ZZ") = "ZZaZZbZZcZZ" * StringUtils.replaceAll("<__>\n<__>", Pattern.compile("<.*>"), "z") = "z\nz" * StringUtils.replaceAll("<__>\n<__>", Pattern.compile("<.*>", Pattern.DOTALL), "z") = "z" * StringUtils.replaceAll("<__>\n<__>", Pattern.compile("(?s)<.*>"), "z") = "z" * StringUtils.replaceAll("ABCabc123", Pattern.compile("[a-z]"), "_") = "ABC___123" * StringUtils.replaceAll("ABCabc123", Pattern.compile("[^A-Z0-9]+"), "_") = "ABC_123" * StringUtils.replaceAll("ABCabc123", Pattern.compile("[^A-Z0-9]+"), "") = "ABC123" * StringUtils.replaceAll("Lorem ipsum dolor sit", Pattern.compile("( +)([a-z]+)"), "_$2") = "Lorem_ipsum_dolor_sit" * </pre> * * @param text text to search and replace in, may be null * @param regex the regular expression pattern to which this string is to be matched * @param replacement the string to be substituted for each match * @return the text with any replacements processed, * {@code null} if null String input * * @see java.util.regex.Matcher#replaceAll(String) * @see java.util.regex.Pattern */ public static String replaceAll(final String text, final Pattern regex, final String replacement) { if (text == null || regex == null || replacement == null) { return text; } return regex.matcher(text).replaceAll(replacement); } /** * <p>Replaces each substring of the text String that matches the given regular expression * with the given replacement.</p> * * This method is a {@code null} safe equivalent to: * <ul> * <li>{@code text.replaceAll(regex, replacement)}</li> * <li>{@code Pattern.compile(regex).matcher(text).replaceAll(replacement)}</li> * </ul> * * <p>A {@code null} reference passed to this method is a no-op.</p> * * <p>Unlike in the {@link #replacePattern(String, String, String)} method, the {@link Pattern#DOTALL} option * is NOT automatically added. * To use the DOTALL option prepend <code>"(?s)"</code> to the regex. * DOTALL is also known as single-line mode in Perl.</p> * * <pre> * StringUtils.replaceAll(null, *, *) = null * StringUtils.replaceAll("any", (String) null, *) = "any" * StringUtils.replaceAll("any", *, null) = "any" * StringUtils.replaceAll("", "", "zzz") = "zzz" * StringUtils.replaceAll("", ".*", "zzz") = "zzz" * StringUtils.replaceAll("", ".+", "zzz") = "" * StringUtils.replaceAll("abc", "", "ZZ") = "ZZaZZbZZcZZ" * StringUtils.replaceAll("<__>\n<__>", "<.*>", "z") = "z\nz" * StringUtils.replaceAll("<__>\n<__>", "(?s)<.*>", "z") = "z" * StringUtils.replaceAll("ABCabc123", "[a-z]", "_") = "ABC___123" * StringUtils.replaceAll("ABCabc123", "[^A-Z0-9]+", "_") = "ABC_123" * StringUtils.replaceAll("ABCabc123", "[^A-Z0-9]+", "") = "ABC123" * StringUtils.replaceAll("Lorem ipsum dolor sit", "( +)([a-z]+)", "_$2") = "Lorem_ipsum_dolor_sit" * </pre> * * @param text text to search and replace in, may be null * @param regex the regular expression to which this string is to be matched * @param replacement the string to be substituted for each match * @return the text with any replacements processed, * {@code null} if null String input * * @throws java.util.regex.PatternSyntaxException * if the regular expression's syntax is invalid * * @see #replacePattern(String, String, String) * @see String#replaceAll(String, String) * @see java.util.regex.Pattern * @see java.util.regex.Pattern#DOTALL */ public static String replaceAll(final String text, final String regex, final String replacement) { if (text == null || regex == null || replacement == null) { return text; } return text.replaceAll(regex, replacement); } /** * <p>Replaces the first substring of the text string that matches the given regular expression pattern * with the given replacement.</p> * * This method is a {@code null} safe equivalent to: * <ul> * <li>{@code pattern.matcher(text).replaceFirst(replacement)}</li> * </ul> * * <p>A {@code null} reference passed to this method is a no-op.</p> * * <pre> * StringUtils.replaceFirst(null, *, *) = null * StringUtils.replaceFirst("any", (Pattern) null, *) = "any" * StringUtils.replaceFirst("any", *, null) = "any" * StringUtils.replaceFirst("", Pattern.compile(""), "zzz") = "zzz" * StringUtils.replaceFirst("", Pattern.compile(".*"), "zzz") = "zzz" * StringUtils.replaceFirst("", Pattern.compile(".+"), "zzz") = "" * StringUtils.replaceFirst("abc", Pattern.compile(""), "ZZ") = "ZZabc" * StringUtils.replaceFirst("<__>\n<__>", Pattern.compile("<.*>"), "z") = "z\n<__>" * StringUtils.replaceFirst("<__>\n<__>", Pattern.compile("(?s)<.*>"), "z") = "z" * StringUtils.replaceFirst("ABCabc123", Pattern.compile("[a-z]"), "_") = "ABC_bc123" * StringUtils.replaceFirst("ABCabc123abc", Pattern.compile("[^A-Z0-9]+"), "_") = "ABC_123abc" * StringUtils.replaceFirst("ABCabc123abc", Pattern.compile("[^A-Z0-9]+"), "") = "ABC123abc" * StringUtils.replaceFirst("Lorem ipsum dolor sit", Pattern.compile("( +)([a-z]+)"), "_$2") = "Lorem_ipsum dolor sit" * </pre> * * @param text text to search and replace in, may be null * @param regex the regular expression pattern to which this string is to be matched * @param replacement the string to be substituted for the first match * @return the text with the first replacement processed, * {@code null} if null String input * * @see java.util.regex.Matcher#replaceFirst(String) * @see java.util.regex.Pattern */ public static String replaceFirst(final String text, final Pattern regex, final String replacement) { if (text == null || regex == null || replacement == null) { return text; } return regex.matcher(text).replaceFirst(replacement); } /** * <p>Replaces the first substring of the text string that matches the given regular expression * with the given replacement.</p> * * This method is a {@code null} safe equivalent to: * <ul> * <li>{@code text.replaceFirst(regex, replacement)}</li> * <li>{@code Pattern.compile(regex).matcher(text).replaceFirst(replacement)}</li> * </ul> * * <p>A {@code null} reference passed to this method is a no-op.</p> * * <p>The {@link Pattern#DOTALL} option is NOT automatically added. * To use the DOTALL option prepend <code>"(?s)"</code> to the regex. * DOTALL is also known as single-line mode in Perl.</p> * * <pre> * StringUtils.replaceFirst(null, *, *) = null * StringUtils.replaceFirst("any", (String) null, *) = "any" * StringUtils.replaceFirst("any", *, null) = "any" * StringUtils.replaceFirst("", "", "zzz") = "zzz" * StringUtils.replaceFirst("", ".*", "zzz") = "zzz" * StringUtils.replaceFirst("", ".+", "zzz") = "" * StringUtils.replaceFirst("abc", "", "ZZ") = "ZZabc" * StringUtils.replaceFirst("<__>\n<__>", "<.*>", "z") = "z\n<__>" * StringUtils.replaceFirst("<__>\n<__>", "(?s)<.*>", "z") = "z" * StringUtils.replaceFirst("ABCabc123", "[a-z]", "_") = "ABC_bc123" * StringUtils.replaceFirst("ABCabc123abc", "[^A-Z0-9]+", "_") = "ABC_123abc" * StringUtils.replaceFirst("ABCabc123abc", "[^A-Z0-9]+", "") = "ABC123abc" * StringUtils.replaceFirst("Lorem ipsum dolor sit", "( +)([a-z]+)", "_$2") = "Lorem_ipsum dolor sit" * </pre> * * @param text text to search and replace in, may be null * @param regex the regular expression to which this string is to be matched * @param replacement the string to be substituted for the first match * @return the text with the first replacement processed, * {@code null} if null String input * * @throws java.util.regex.PatternSyntaxException * if the regular expression's syntax is invalid * * @see String#replaceFirst(String, String) * @see java.util.regex.Pattern * @see java.util.regex.Pattern#DOTALL */ public static String replaceFirst(final String text, final String regex, final String replacement) { if (text == null || regex == null || replacement == null) { return text; } return text.replaceFirst(regex, replacement); } /** * <p>Replaces each substring of the source String that matches the given regular expression with the given * replacement using the {@link Pattern#DOTALL} option. DOTALL is also known as single-line mode in Perl.</p> * * This call is a {@code null} safe equivalent to: * <ul> * <li>{@code text.replaceAll("(?s)" + regex, replacement)}</li> * <li>{@code Pattern.compile(regex, Pattern.DOTALL).matcher(text).replaceAll(replacement)}</li> * </ul> * * <p>A {@code null} reference passed to this method is a no-op.</p> * * <pre> * StringUtils.replacePattern(null, *, *) = null * StringUtils.replacePattern("any", (String) null, *) = "any" * StringUtils.replacePattern("any", *, null) = "any" * StringUtils.replacePattern("", "", "zzz") = "zzz" * StringUtils.replacePattern("", ".*", "zzz") = "zzz" * StringUtils.replacePattern("", ".+", "zzz") = "" * StringUtils.replacePattern("<__>\n<__>", "<.*>", "z") = "z" * StringUtils.replacePattern("ABCabc123", "[a-z]", "_") = "ABC___123" * StringUtils.replacePattern("ABCabc123", "[^A-Z0-9]+", "_") = "ABC_123" * StringUtils.replacePattern("ABCabc123", "[^A-Z0-9]+", "") = "ABC123" * StringUtils.replacePattern("Lorem ipsum dolor sit", "( +)([a-z]+)", "_$2") = "Lorem_ipsum_dolor_sit" * </pre> * * @param text * the source string * @param regex * the regular expression to which this string is to be matched * @param replacement * the string to be substituted for each match * @return The resulting {@code String} * @see #replaceAll(String, String, String) * @see String#replaceAll(String, String) * @see Pattern#DOTALL */ public static String replacePattern(final String text, final String regex, final String replacement) { if (text == null || regex == null || replacement == null) { return text; } return Pattern.compile(regex, Pattern.DOTALL).matcher(text).replaceAll(replacement); } }