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 import java.util.Random;
  25 import java.util.SplittableRandom;
  26 
  27 public class RandomSeed {
  28     private long seed = 0L;
  29     private Random rnd = null;
  30     private SplittableRandom srnd = null;
  31 
  32     public RandomSeed(boolean isSplittableRandom) {
  33         init(isSplittableRandom);
  34     }
  35 
  36     private void init(boolean isSplittableRandom) {
  37         // obtain seed from environment if supplied
  38         boolean isSeedProvided = false;
  39         try {
  40             // note that Long.valueOf(null) also throws a NumberFormatException
  41             // so if the property is undefined this will still work correctly
  42             seed = Long.valueOf(System.getProperty("seed"));
  43             isSeedProvided = true;
  44         } catch (NumberFormatException e) {
  45             // do nothing: isSeedProvided is already false
  46         }
  47 
  48         // if no seed from environment, create a fresh one
  49         Random tmpRnd = null;
  50         if (!isSeedProvided) {
  51             tmpRnd = new Random();
  52             seed = tmpRnd.nextLong();
  53         }
  54 
  55         // create the PRNG
  56         if (isSplittableRandom) {
  57             srnd = new SplittableRandom(seed);
  58         } else {
  59             rnd = tmpRnd != null ? tmpRnd : new Random();
  60             rnd.setSeed(seed);
  61         }
  62     }
  63 
  64     public Random getRandom() {
  65         if (rnd == null) {
  66             throw new IllegalStateException("Variable of type Random not initialized");
  67         }
  68         return rnd;
  69     }
  70 
  71     public SplittableRandom getSplittableRandom() {
  72         if (srnd == null) {
  73             throw new IllegalStateException("Variable of type SplittableRandom not initialized");
  74         }
  75         return srnd;
  76     }
  77 
  78     public long getSeed() {
  79         return seed;
  80     }
  81 }