Here you can find the source of replace(String s, char oldSub, String newSub)
public static String replace(String s, char oldSub, String newSub)
//package com.java2s; /**//from www. j a v a 2s . c om * Copyright 2013 ?????? * * 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. */ public class Main { public static final String EMPTY = ""; public static String replace(String s, char oldSub, char newSub) { return replace(s, oldSub, Character.valueOf(newSub)); } public static String replace(String s, char oldSub, String newSub) { if ((s == null) || (newSub == null)) { return null; } char[] c = s.toCharArray(); StringBuffer sb = new StringBuffer(); for (int i = 0; i < c.length; i++) { if (c[i] == oldSub) { sb.append(newSub); } else { sb.append(c[i]); } } return sb.toString(); } public static String replace(String s, String oldSub, String newSub) { if ((s == null) || (oldSub == null) || (newSub == null)) { return null; } int y = s.indexOf(oldSub); if (y >= 0) { StringBuffer sb = new StringBuffer(); int length = oldSub.length(); int x = 0; while (x <= y) { sb.append(s.substring(x, y)); sb.append(newSub); x = y + length; y = s.indexOf(oldSub, x); } sb.append(s.substring(x)); return sb.toString(); } else { return s; } } public static String replace(String s, String[] oldSubs, String[] newSubs) { if ((s == null) || (oldSubs == null) || (newSubs == null)) { return null; } if (oldSubs.length != newSubs.length) { return s; } for (int i = 0; i < oldSubs.length; i++) { s = replace(s, oldSubs[i], newSubs[i]); } return s; } public static String replace(String s, String[] oldSubs, char[] newSubs) { if ((s == null) || (oldSubs == null) || (newSubs == null)) { return null; } if (oldSubs.length != newSubs.length) { return s; } for (int i = 0; i < oldSubs.length; i++) { s = replace(s, oldSubs[i], String.valueOf(newSubs[i])); } return s; } public static String substring(String str, int beginIndex) { if (str == null) { return null; } if (beginIndex < 0) { return EMPTY; } if (beginIndex > str.length()) { return EMPTY; } return str.substring(beginIndex); } public static String substring(String str, int beginIndex, int endIndex) { if (str == null) { return null; } if (beginIndex < 0 || endIndex < 0) { return EMPTY; } if (endIndex > str.length()) { endIndex = str.length(); } if (beginIndex > endIndex || beginIndex > str.length()) { return EMPTY; } return str.substring(beginIndex, endIndex); } }