1 /* 2 * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 */ 23 24 package jdk.testlibrary; 25 26 import java.util.Random; 27 import java.util.SplittableRandom; 28 29 /** 30 * Factory class which generates and prints to STDOUT a long-valued seed 31 * for use in initializing a PRNG. An instance of {@code Random} or 32 * {@code SplittableRandom} may likewise be obtained. 33 */ 34 public class RandomFactory { 35 /** 36 * Attempt to obtain the seed from the value of the "seed" property. 37 * @return The seed or {@code null} if the "seed" property was not set or 38 * could not be parsed. 39 */ 40 private static Long getSystemSeed() { 41 Long seed = null; 42 try { 43 // note that Long.valueOf(null) also throws a 44 // NumberFormatException so if the property is undefined this 45 // will still work correctly 46 seed = Long.valueOf(System.getProperty("seed")); 47 } catch (NumberFormatException e) { 48 // do nothing: seed is still null 49 } 50 51 return seed; 52 } 53 54 /** 55 * Obtain a seed from an independent PRNG. 56 * 57 * @return A random seed. 58 */ 59 private static long getRandomSeed() { 60 return new Random().nextLong(); 61 } 62 63 /** 64 * Obtain and print to STDOUT a seed appropriate for initializing a PRNG. 65 * If the system property "seed" is set and has value which may be correctly 66 * parsed it is used, otherwise a seed is generated using an independent 67 * PRNG. 68 * 69 * @return The seed. 70 */ 71 public static long getSeed() { 72 Long seed = getSystemSeed(); 73 if (seed == null) { 74 seed = getRandomSeed(); 75 } 76 System.out.println("Seed from RandomFactory = "+seed+"L"); 77 return seed; 78 } 79 80 /** 81 * Obtain and print to STDOUT a seed and use it to initialize a new 82 * {@code Random} instance which is returned. If the system 83 * property "seed" is set and has value which may be correctly parsed it 84 * is used, otherwise a seed is generated using an independent PRNG. 85 * 86 * @return The {@code Random} instance. 87 */ 88 public static Random getRandom() { 89 return new Random(getSeed()); 90 } 91 92 /** 93 * Obtain and print to STDOUT a seed and use it to initialize a new 94 * {@code SplittableRandom} instance which is returned. If the system 95 * property "seed" is set and has value which may be correctly parsed it 96 * is used, otherwise a seed is generated using an independent PRNG. 97 * 98 * @return The {@code SplittableRandom} instance. 99 */ 100 public static SplittableRandom getSplittableRandom() { 101 return new SplittableRandom(getSeed()); 102 } 103 } 104
