1 /* IntegerUtil.java -- JDK 5 Integer methods with 1.4 API 2 Copyright (C) 2006 Free Software Foundation, Inc. 3 4 This file is part of GNU Classpath. 5 6 GNU Classpath is free software; you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 2, or (at your option) 9 any later version. 10 11 GNU Classpath is distributed in the hope that it will be useful, but 12 WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with GNU Classpath; see the file COPYING. If not, write to the 18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19 02110-1301 USA. 20 21 Linking this library statically or dynamically with other modules is 22 making a combined work based on this library. Thus, the terms and 23 conditions of the GNU General Public License cover the whole 24 combination. 25 26 As a special exception, the copyright holders of this library give you 27 permission to link this library with independent modules to produce an 28 executable, regardless of the license terms of these independent 29 modules, and to copy and distribute the resulting executable under 30 terms of your choice, provided that you also meet, for each linked 31 independent module, the terms and conditions of the license of that 32 module. An independent module is a module which is not derived from 33 or based on this library. If you modify this library, you may extend 34 this exception to your version of the library, but you are not 35 obligated to do so. If you do not wish to do so, delete this 36 exception statement from your version. */ 37 38 39 package gnu.java.security.util; 40 41 import java.util.LinkedHashMap; 42 import java.util.Map; 43 44 /** 45 * Utility class which offers Integer related methods found in RI's version 5 46 * but written with RI's 1.4 API. 47 */ 48 public abstract class IntegerUtil 49 { 50 /** Maximum size of our cache of constructed Integers. */ 51 private static final int CACHE_SIZE = 100; 52 /** LRU (Least Recently Used) cache, of the last accessed 100 Integers. */ 53 private static final Map cache = new LinkedHashMap(CACHE_SIZE + 1, 0.75F, true) 54 { 55 public boolean removeEldestEntry(Map.Entry entry) 56 { 57 return size() > CACHE_SIZE; 58 } 59 }; 60 61 /** Trivial private constructor to enforce Singleton usage. */ IntegerUtil()62 private IntegerUtil() 63 { 64 super(); 65 } 66 67 /** 68 * Similar to {@link Integer#valueOf(String)} except it caches the result in 69 * a local LRU cache of 100 elements, organized by access order. 70 * <p> 71 * This method MUST be used in the gnu.java.security and gnu.javax.crypto 72 * packages to ensure they would work with a version 1.4 only of the Java 73 * class library API. 74 * 75 * @param aString a string representation of an integer. 76 * @return the {@link Integer} object representing the designated string. 77 */ valueOf(String aString)78 public static final Integer valueOf(String aString) 79 { 80 Integer result; 81 synchronized (cache) 82 { 83 result = (Integer) cache.get(aString); 84 if (result == null) 85 { 86 result = Integer.valueOf(aString); 87 cache.put(aString, result); 88 } 89 } 90 return result; 91 } 92 93 /** 94 * Simulates the <code>valueOf(int)</code> method found in {@link Integer} of 95 * the RI's version 1.5 using a local LRU cache of 100 elements, organized by 96 * access order. 97 * <p> 98 * This method MUST be used in the gnu.java.security and gnu.javax.crypto 99 * packages to ensure they would work with a version 1.4 only of the Java 100 * class library API. 101 * 102 * @param anInt a decimal integer. 103 * @return the {@link Integer} object representing the designated primitive. 104 */ valueOf(int anInt)105 public static final Integer valueOf(int anInt) 106 { 107 return valueOf(Integer.toString(anInt, 10)); 108 } 109 } 110