Java examples for java.lang:String Replace
Replaces all occurrences of a character in a String with another.
/*/*from www .j a v a 2 s . co m*/ * Copyright 2013 Guidewire Software, Inc. */ /** * This class is based, in part, on org.apache.commons.lang.StringUtils and is intended * to break the dependency on that project. * * @author <a href="http://jakarta.apache.org/turbine/">Apache Jakarta Turbine</a> * @author <a href="mailto:jon@latchkey.com">Jon S. Stevens</a> * @author Daniel L. Rall * @author <a href="mailto:gcoladonato@yahoo.com">Greg Coladonato</a> * @author <a href="mailto:ed@apache.org">Ed Korthof</a> * @author <a href="mailto:rand_mcneely@yahoo.com">Rand McNeely</a> * @author Stephen Colebourne * @author <a href="mailto:fredrik@westermarck.com">Fredrik Westermarck</a> * @author Holger Krauth * @author <a href="mailto:alex@purpletech.com">Alexander Day Chaffee</a> * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a> * @author Arun Mammen Thomas * @author Gary Gregory * @author Phil Steitz * @author Al Chou * @author Michael Davey * @author Reuben Sivan * @author Chris Hyzer * Johnson */ //package com.java2s; public class Main { public static void main(String[] argv) { String str = "java2s.com"; char searchChar = 'a'; char replaceChar = 'a'; System.out.println(replaceChars(str, searchChar, replaceChar)); } /** * The empty String <code>""</code>. * @since 2.0 */ public static final String EMPTY = ""; /** * <p>Replaces all occurrences of a character in a String with another. * This is a null-safe version of {@link String#replace(char, char)}.</p> * * <p>A <code>null</code> string input returns <code>null</code>. * An empty ("") string input returns an empty string.</p> * * <pre> * replaceChars(null, *, *) = null * replaceChars("", *, *) = "" * replaceChars("abcba", 'b', 'y') = "aycya" * replaceChars("abcba", 'z', 'y') = "abcba" * </pre> * * @param str String to replace characters in, may be null * @param searchChar the character to search for, may be null * @param replaceChar the character to replace, may be null * @return modified String, <code>null</code> if null string input * @since 2.0 */ public static String replaceChars(String str, char searchChar, char replaceChar) { if (str == null) { return null; } return str.replace(searchChar, replaceChar); } /** * <p>Replaces multiple characters in a String in one go. * This method can also be used to delete characters.</p> * * <p>For example:<br /> * <code>replaceChars("hello", "ho", "jy") = jelly</code>.</p> * * <p>A <code>null</code> string input returns <code>null</code>. * An empty ("") string input returns an empty string. * A null or empty set of search characters returns the input string.</p> * * <p>The length of the search characters should normally equal the length * of the replace characters. * If the search characters is longer, then the extra search characters * are deleted. * If the search characters is shorter, then the extra replace characters * are ignored.</p> * * <pre> * replaceChars(null, *, *) = null * replaceChars("", *, *) = "" * replaceChars("abc", null, *) = "abc" * replaceChars("abc", "", *) = "abc" * replaceChars("abc", "b", null) = "ac" * replaceChars("abc", "b", "") = "ac" * replaceChars("abcba", "bc", "yz") = "ayzya" * replaceChars("abcba", "bc", "y") = "ayya" * replaceChars("abcba", "bc", "yzx") = "ayzya" * </pre> * * @param str String to replace characters in, may be null * @param searchChars a set of characters to search for, may be null * @param replaceChars a set of characters to replace, may be null * @return modified String, <code>null</code> if null string input * @since 2.0 */ public static String replaceChars(String str, String searchChars, String replaceChars) { if (isEmpty(str) || isEmpty(searchChars)) { return str; } if (replaceChars == null) { replaceChars = EMPTY; } boolean modified = false; int replaceCharsLength = replaceChars.length(); int strLength = str.length(); StringBuilder buf = new StringBuilder(strLength); for (int i = 0; i < strLength; i++) { char ch = str.charAt(i); int index = searchChars.indexOf(ch); if (index >= 0) { modified = true; if (index < replaceCharsLength) { buf.append(replaceChars.charAt(index)); } } else { buf.append(ch); } } if (modified) { return buf.toString(); } return str; } /** * <p>Replaces all occurrences of a String within another String.</p> * * <p>A <code>null</code> reference passed to this method is a no-op.</p> * * <pre> * replace(null, *, *) = null * replace("", *, *) = "" * replace("any", null, *) = "any" * replace("any", *, null) = "any" * replace("any", "", *) = "any" * replace("aba", "a", null) = "aba" * replace("aba", "a", "") = "b" * replace("aba", "a", "z") = "zbz" * </pre> * * @see #replace(String text, String searchString, String replacement, int max) * @param text text to search and replace in, may be null * @param searchString the String to search for, may be null * @param replacement the String to replace it with, may be null * @return the text with any replacements processed, * <code>null</code> if null String input */ public static String replace(String text, String searchString, String replacement) { return replace(text, searchString, replacement, -1); } /** * <p>Replaces a String with another String inside a larger String, * for the first <code>max</code> values of the search String.</p> * * <p>A <code>null</code> reference passed to this method is a no-op.</p> * * <pre> * replace(null, *, *, *) = null * replace("", *, *, *) = "" * replace("any", null, *, *) = "any" * replace("any", *, null, *) = "any" * replace("any", "", *, *) = "any" * replace("any", *, *, 0) = "any" * replace("abaa", "a", null, -1) = "abaa" * replace("abaa", "a", "", -1) = "b" * replace("abaa", "a", "z", 0) = "abaa" * replace("abaa", "a", "z", 1) = "zbaa" * replace("abaa", "a", "z", 2) = "zbza" * replace("abaa", "a", "z", -1) = "zbzz" * </pre> * * @param text text to search and replace in, may be null * @param searchString the String to search for, may be null * @param replacement the String to replace it with, may be null * @param max maximum number of values to replace, or <code>-1</code> if no maximum * @return the text with any replacements processed, * <code>null</code> if null String input */ public static String replace(String text, String searchString, String replacement, int max) { if (isEmpty(text) || isEmpty(searchString) || replacement == null || max == 0) { return text; } int start = 0; int end = text.indexOf(searchString, start); if (end == -1) { return text; } int replLength = searchString.length(); int increase = replacement.length() - replLength; increase = (increase < 0 ? 0 : increase); increase *= (max < 0 ? 16 : (max > 64 ? 64 : max)); StringBuilder buf = new StringBuilder(text.length() + increase); while (end != -1) { buf.append(text.substring(start, end)).append(replacement); start = end + replLength; if (--max == 0) { break; } end = text.indexOf(searchString, start); } buf.append(text.substring(start)); return buf.toString(); } /** * <p>Checks if a String is empty ("") or null.</p> * * <pre> * StringUtils.isEmpty(null) = true * StringUtils.isEmpty("") = true * StringUtils.isEmpty(" ") = false * StringUtils.isEmpty("bob") = false * StringUtils.isEmpty(" bob ") = false * </pre> * * <p>NOTE: This method changed in Lang version 2.0. * It no longer trims the String. * That functionality is available in isBlank().</p> * * @param str the String to check, may be null * @return <code>true</code> if the String is empty or null */ public static boolean isEmpty(String str) { return str == null || str.length() == 0; } /** * Gets a String's length or <code>0</code> if the String is <code>null</code>. * * @param str * a String or <code>null</code> * @return String length or <code>0</code> if the String is <code>null</code>. * @since 2.4 */ public static int length(String str) { return str == null ? 0 : str.length(); } /** * <p>Finds the first index within a String, handling <code>null</code>. * This method uses {@link String#indexOf(int)}.</p> * * <p>A <code>null</code> or empty ("") String will return <code>-1</code>.</p> * * <pre> * indexOf(null, *) = -1 * indexOf("", *) = -1 * indexOf("aabaabaa", 'a') = 0 * indexOf("aabaabaa", 'b') = 2 * </pre> * * @param str the String to check, may be null * @param searchChar the character to find * @return the first index of the search character, * -1 if no match or <code>null</code> string input * @since 2.0 */ public static int indexOf(String str, char searchChar) { if (isEmpty(str)) { return -1; } return str.indexOf(searchChar); } /** * <p>Finds the first index within a String from a start position, * handling <code>null</code>. * This method uses {@link String#indexOf(int, int)}.</p> * * <p>A <code>null</code> or empty ("") String will return <code>-1</code>. * A negative start position is treated as zero. * A start position greater than the string length returns <code>-1</code>.</p> * * <pre> * indexOf(null, *, *) = -1 * indexOf("", *, *) = -1 * indexOf("aabaabaa", 'b', 0) = 2 * indexOf("aabaabaa", 'b', 3) = 5 * indexOf("aabaabaa", 'b', 9) = -1 * indexOf("aabaabaa", 'b', -1) = 2 * </pre> * * @param str the String to check, may be null * @param searchChar the character to find * @param startPos the start position, negative treated as zero * @return the first index of the search character, * -1 if no match or <code>null</code> string input * @since 2.0 */ public static int indexOf(String str, char searchChar, int startPos) { if (isEmpty(str)) { return -1; } return str.indexOf(searchChar, startPos); } /** * <p>Finds the first index within a String, handling <code>null</code>. * This method uses {@link String#indexOf(String)}.</p> * * <p>A <code>null</code> String will return <code>-1</code>.</p> * * <pre> * indexOf(null, *) = -1 * indexOf(*, null) = -1 * indexOf("", "") = 0 * indexOf("aabaabaa", "a") = 0 * indexOf("aabaabaa", "b") = 2 * indexOf("aabaabaa", "ab") = 1 * indexOf("aabaabaa", "") = 0 * </pre> * * @param str the String to check, may be null * @param searchStr the String to find, may be null * @return the first index of the search String, * -1 if no match or <code>null</code> string input * @since 2.0 */ public static int indexOf(String str, String searchStr) { if (str == null || searchStr == null) { return -1; } return str.indexOf(searchStr); } /** * <p>Finds the first index within a String, handling <code>null</code>. * This method uses {@link String#indexOf(String, int)}.</p> * * <p>A <code>null</code> String will return <code>-1</code>. * A negative start position is treated as zero. * An empty ("") search String always matches. * A start position greater than the string length only matches * an empty search String.</p> * * <pre> * indexOf(null, *, *) = -1 * indexOf(*, null, *) = -1 * indexOf("", "", 0) = 0 * indexOf("aabaabaa", "a", 0) = 0 * indexOf("aabaabaa", "b", 0) = 2 * indexOf("aabaabaa", "ab", 0) = 1 * indexOf("aabaabaa", "b", 3) = 5 * indexOf("aabaabaa", "b", 9) = -1 * indexOf("aabaabaa", "b", -1) = 2 * indexOf("aabaabaa", "", 2) = 2 * indexOf("abc", "", 9) = 3 * </pre> * * @param str the String to check, may be null * @param searchStr the String to find, may be null * @param startPos the start position, negative treated as zero * @return the first index of the search String, * -1 if no match or <code>null</code> string input * @since 2.0 */ public static int indexOf(String str, String searchStr, int startPos) { if (str == null || searchStr == null) { return -1; } // JDK1.2/JDK1.3 have a bug, when startPos > str.length for "", hence if (searchStr.length() == 0 && startPos >= str.length()) { return str.length(); } return str.indexOf(searchStr, startPos); } /** * <p>Gets a substring from the specified String avoiding exceptions.</p> * * <p>A negative start position can be used to start <code>n</code> * characters from the end of the String.</p> * * <p>A <code>null</code> String will return <code>null</code>. * An empty ("") String will return "".</p> * * <pre> * substring(null, *) = null * substring("", *) = "" * substring("abc", 0) = "abc" * substring("abc", 2) = "c" * substring("abc", 4) = "" * substring("abc", -2) = "bc" * substring("abc", -4) = "abc" * </pre> * * @param str the String to get the substring from, may be null * @param start the position to start from, negative means * count back from the end of the String by this many characters * @return substring from start position, <code>null</code> if null String input */ public static String substring(String str, int start) { if (str == null) { return null; } // handle negatives, which means last n characters if (start < 0) { start = str.length() + start; // remember start is negative } if (start < 0) { start = 0; } if (start > str.length()) { return EMPTY; } return str.substring(start); } /** * <p>Gets a substring from the specified String avoiding exceptions.</p> * * <p>A negative start position can be used to start/end <code>n</code> * characters from the end of the String.</p> * * <p>The returned substring starts with the character in the <code>start</code> * position and ends before the <code>end</code> position. All position counting is * zero-based -- i.e., to start at the beginning of the string use * <code>start = 0</code>. Negative start and end positions can be used to * specify offsets relative to the end of the String.</p> * * <p>If <code>start</code> is not strictly to the left of <code>end</code>, "" * is returned.</p> * * <pre> * substring(null, *, *) = null * substring("", * , *) = ""; * substring("abc", 0, 2) = "ab" * substring("abc", 2, 0) = "" * substring("abc", 2, 4) = "c" * substring("abc", 4, 6) = "" * substring("abc", 2, 2) = "" * substring("abc", -2, -1) = "b" * substring("abc", -4, 2) = "ab" * </pre> * * @param str the String to get the substring from, may be null * @param start the position to start from, negative means * count back from the end of the String by this many characters * @param end the position to end at (exclusive), negative means * count back from the end of the String by this many characters * @return substring from start position to end positon, * <code>null</code> if null String input */ public static String substring(String str, int start, int end) { if (str == null) { return null; } // handle negatives if (end < 0) { end = str.length() + end; // remember end is negative } if (start < 0) { start = str.length() + start; // remember start is negative } // check length next if (end > str.length()) { end = str.length(); } // if start is greater than end, return "" if (start > end) { return EMPTY; } if (start < 0) { start = 0; } if (end < 0) { end = 0; } return str.substring(start, end); } }