f9a9e68c05
Create a utility class which creates a pseudorandom number generator (PRNG) and retains the seed. Use this class in java.math tests which use a PRNG. Always print the seed value before the PRNG is used. Reviewed-by: darcy
82 lines
2.7 KiB
Java
82 lines
2.7 KiB
Java
/*
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* Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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import java.util.Random;
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import java.util.SplittableRandom;
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public class RandomSeed {
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private long seed = 0L;
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private Random rnd = null;
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private SplittableRandom srnd = null;
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public RandomSeed(boolean isSplittableRandom) {
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init(isSplittableRandom);
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}
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private void init(boolean isSplittableRandom) {
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// obtain seed from environment if supplied
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boolean isSeedProvided = false;
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try {
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// note that Long.valueOf(null) also throws a NumberFormatException
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// so if the property is undefined this will still work correctly
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seed = Long.valueOf(System.getProperty("seed"));
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isSeedProvided = true;
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} catch (NumberFormatException e) {
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// do nothing: isSeedProvided is already false
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}
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// if no seed from environment, create a fresh one
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Random tmpRnd = null;
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if (!isSeedProvided) {
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tmpRnd = new Random();
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seed = tmpRnd.nextLong();
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}
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// create the PRNG
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if (isSplittableRandom) {
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srnd = new SplittableRandom(seed);
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} else {
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rnd = tmpRnd != null ? tmpRnd : new Random();
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rnd.setSeed(seed);
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}
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}
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public Random getRandom() {
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if (rnd == null) {
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throw new IllegalStateException("Variable of type Random not initialized");
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}
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return rnd;
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}
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public SplittableRandom getSplittableRandom() {
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if (srnd == null) {
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throw new IllegalStateException("Variable of type SplittableRandom not initialized");
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}
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return srnd;
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}
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public long getSeed() {
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return seed;
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}
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}
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