Java tutorial
/** * Copyright (C) 2010-2016 Gordon Fraser, Andrea Arcuri and EvoSuite * contributors * * This file is part of EvoSuite. * * EvoSuite is free software: you can redistribute it and/or modify it * under the terms of the GNU Lesser General Public License as published * by the Free Software Foundation, either version 3.0 of the License, or * (at your option) any later version. * * EvoSuite 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 * Lesser Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with EvoSuite. If not, see <http://www.gnu.org/licenses/>. */ package org.evosuite.utils; import org.apache.commons.lang3.StringEscapeUtils; public abstract class StringUtil { public static String getEscapedString(String original) { char[] charArray = StringEscapeUtils.escapeJava((String) original).toCharArray(); StringBuilder sb = new StringBuilder(); for (int i = 0; i < charArray.length; ++i) { char a = charArray[i]; if (a > 255) { sb.append("\\u"); sb.append(Integer.toHexString(a)); } else { sb.append(a); } } return sb.toString(); } /** * <p>escapeQuotes</p> * * @param str a {@link java.lang.String} object. * @return a {@link java.lang.String} object. */ public static String escapeQuotes(String str) { return str.replaceAll("['\"\\\\]", "\\\\$0"); } /** * Compares all Strings in an array and returns the initial sequence of * characters that is common to all of them. * * For example, * <code>getCommonPrefix(new String[] {"i am a machine", "i am a robot"}) -> "i am a "</code> * * <pre> * StringUtils.getCommonPrefix(null) = "" * StringUtils.getCommonPrefix(new String[] {}) = "" * StringUtils.getCommonPrefix(new String[] {"abc"}) = "abc" * StringUtils.getCommonPrefix(new String[] {null, null}) = "" * StringUtils.getCommonPrefix(new String[] {"", ""}) = "" * StringUtils.getCommonPrefix(new String[] {"", null}) = "" * StringUtils.getCommonPrefix(new String[] {"abc", null, null}) = "" * StringUtils.getCommonPrefix(new String[] {null, null, "abc"}) = "" * StringUtils.getCommonPrefix(new String[] {"", "abc"}) = "" * StringUtils.getCommonPrefix(new String[] {"abc", ""}) = "" * StringUtils.getCommonPrefix(new String[] {"abc", "abc"}) = "abc" * StringUtils.getCommonPrefix(new String[] {"abc", "a"}) = "a" * StringUtils.getCommonPrefix(new String[] {"ab", "abxyz"}) = "ab" * StringUtils.getCommonPrefix(new String[] {"abcde", "abxyz"}) = "ab" * StringUtils.getCommonPrefix(new String[] {"abcde", "xyz"}) = "" * StringUtils.getCommonPrefix(new String[] {"xyz", "abcde"}) = "" * StringUtils.getCommonPrefix(new String[] {"i am a machine", "i am a robot"}) = "i am a " * </pre> * * @param strs * array of String objects, entries may be null * @return the initial sequence of characters that are common to all Strings * in the array; empty String if the array is null, the elements are * all null or if there is no common prefix. * @since 2.4 */ public static String getCommonPrefix(String[] strs) { if (strs == null || strs.length == 0) { return ""; } int smallestIndexOfDiff = indexOfDifference(strs); if (smallestIndexOfDiff == -1) { // all strings were identical if (strs[0] == null) { return ""; } return strs[0]; } else if (smallestIndexOfDiff == 0) { // there were no common initial characters return ""; } else { // we found a common initial character sequence return strs[0].substring(0, smallestIndexOfDiff); } } /** * Compares all Strings in an array and returns the index at which the * Strings begin to differ. * * For example, * <code>indexOfDifference(new String[] {"i am a machine", "i am a robot"}) -> 7</code> * * <pre> * StringUtils.indexOfDifference(null) = -1 * StringUtils.indexOfDifference(new String[] {}) = -1 * StringUtils.indexOfDifference(new String[] {"abc"}) = -1 * StringUtils.indexOfDifference(new String[] {null, null}) = -1 * StringUtils.indexOfDifference(new String[] {"", ""}) = -1 * StringUtils.indexOfDifference(new String[] {"", null}) = 0 * StringUtils.indexOfDifference(new String[] {"abc", null, null}) = 0 * StringUtils.indexOfDifference(new String[] {null, null, "abc"}) = 0 * StringUtils.indexOfDifference(new String[] {"", "abc"}) = 0 * StringUtils.indexOfDifference(new String[] {"abc", ""}) = 0 * StringUtils.indexOfDifference(new String[] {"abc", "abc"}) = -1 * StringUtils.indexOfDifference(new String[] {"abc", "a"}) = 1 * StringUtils.indexOfDifference(new String[] {"ab", "abxyz"}) = 2 * StringUtils.indexOfDifference(new String[] {"abcde", "abxyz"}) = 2 * StringUtils.indexOfDifference(new String[] {"abcde", "xyz"}) = 0 * StringUtils.indexOfDifference(new String[] {"xyz", "abcde"}) = 0 * StringUtils.indexOfDifference(new String[] {"i am a machine", "i am a robot"}) = 7 * </pre> * * @param strs * array of strings, entries may be null * @return the index where the strings begin to differ; -1 if they are all * equal * @since 2.4 */ public static int indexOfDifference(String[] strs) { if (strs == null || strs.length <= 1) { return -1; } boolean anyStringNull = false; boolean allStringsNull = true; int arrayLen = strs.length; int shortestStrLen = Integer.MAX_VALUE; int longestStrLen = 0; // find the min and max string lengths; this avoids checking to make // sure we are not exceeding the length of the string each time through // the bottom loop. for (int i = 0; i < arrayLen; i++) { if (strs[i] == null) { anyStringNull = true; shortestStrLen = 0; } else { allStringsNull = false; shortestStrLen = Math.min(strs[i].length(), shortestStrLen); longestStrLen = Math.max(strs[i].length(), longestStrLen); } } // handle lists containing all nulls or all empty strings if (allStringsNull || (longestStrLen == 0 && !anyStringNull)) { return -1; } // handle lists containing some nulls or some empty strings if (shortestStrLen == 0) { return 0; } // find the position with the first difference across all strings int firstDiff = -1; for (int stringPos = 0; stringPos < shortestStrLen; stringPos++) { char comparisonChar = strs[0].charAt(stringPos); for (int arrayPos = 1; arrayPos < arrayLen; arrayPos++) { if (strs[arrayPos].charAt(stringPos) != comparisonChar) { firstDiff = stringPos; break; } } if (firstDiff != -1) { break; } } if (firstDiff == -1 && shortestStrLen != longestStrLen) { // we compared all of the characters up to the length of the // shortest string and didn't find a match, but the string lengths // vary, so return the length of the shortest string. return shortestStrLen; } return firstDiff; } }