18  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  19  * or visit www.oracle.com if you need additional information or have any
  20  * questions.
  21  */
  22 
  23 /*
  24  * This file is available under and governed by the GNU General Public
  25  * License version 2 only, as published by the Free Software Foundation.
  26  * However, the following notice accompanied the original version of this
  27  * file:
  28  *
  29  * Written by Doug Lea with assistance from members of JCP JSR-166
  30  * Expert Group and released to the public domain, as explained at
  31  * http://creativecommons.org/publicdomain/zero/1.0/
  32  */
  33 
  34 /*
  35  * @test
  36  * @bug 4949279 6937857
  37  * @summary Independent instantiations of Random() have distinct seeds.

  38  */
  39 
  40 import java.util.ArrayList;
  41 import java.util.HashSet;
  42 import java.util.List;
  43 import java.util.Random;
  44 
  45 public class DistinctSeeds {
  46     public static void main(String[] args) throws Exception {
  47         // Strictly speaking, it is possible for these to randomly fail,
  48         // but the probability should be small (approximately 2**-48).
  49         if (new Random().nextLong() == new Random().nextLong() ||
  50             new Random().nextLong() == new Random().nextLong())
  51             throw new RuntimeException("Random() seeds not unique.");
  52 
  53         // Now try generating seeds concurrently
  54         class RandomCollector implements Runnable {
  55             long[] randoms = new long[1<<17];
  56             public void run() {
  57                 for (int i = 0; i < randoms.length; i++)

  18  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  19  * or visit www.oracle.com if you need additional information or have any
  20  * questions.
  21  */
  22 
  23 /*
  24  * This file is available under and governed by the GNU General Public
  25  * License version 2 only, as published by the Free Software Foundation.
  26  * However, the following notice accompanied the original version of this
  27  * file:
  28  *
  29  * Written by Doug Lea with assistance from members of JCP JSR-166
  30  * Expert Group and released to the public domain, as explained at
  31  * http://creativecommons.org/publicdomain/zero/1.0/
  32  */
  33 
  34 /*
  35  * @test
  36  * @bug 4949279 6937857
  37  * @summary Independent instantiations of Random() have distinct seeds.
  38  * @key randomness
  39  */
  40 
  41 import java.util.ArrayList;
  42 import java.util.HashSet;
  43 import java.util.List;
  44 import java.util.Random;
  45 
  46 public class DistinctSeeds {
  47     public static void main(String[] args) throws Exception {
  48         // Strictly speaking, it is possible for these to randomly fail,
  49         // but the probability should be small (approximately 2**-48).
  50         if (new Random().nextLong() == new Random().nextLong() ||
  51             new Random().nextLong() == new Random().nextLong())
  52             throw new RuntimeException("Random() seeds not unique.");
  53 
  54         // Now try generating seeds concurrently
  55         class RandomCollector implements Runnable {
  56             long[] randoms = new long[1<<17];
  57             public void run() {
  58                 for (int i = 0; i < randoms.length; i++)