Here you can find the source of longestCommonPrefix(String s1, String s2)
public static String longestCommonPrefix(String s1, String s2)
//package com.java2s; /*//from w w w .ja va2s.c o m * Copyright (C) 2011 Matus Goljer * This file is a part of Project DASik, an IRC bot. * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. */ public class Main { public static String longestCommonPrefix(String s1, String s2) { if (s1.length() > s2.length()) { String tmp = s1; s1 = s2; s2 = tmp; } int i = 0; while (i < s1.length() && Character.toUpperCase(s1.charAt(i)) == Character.toUpperCase(s2.charAt(i))) { i++; } return s1.substring(0, i); } }