util/Random/DistinctSeeds.java

/**
 * @test %I% %E%
 * @bug 4949279
 * @summary Independent instantiations of Random() have distinct seeds.
 */

/*
 * Written by Doug Lea with assistance from members of JCP JSR-166
 * Expert Group and released to the public domain, as explained at
 * http://creativecommons.org/licenses/publicdomain
 */


import java.util.Random;

public class DistinctSeeds {
    public static void main(String[] args) throws Exception {
        // Strictly speaking, it is possible for these to randomly fail,
        // but the probability should be *extremely* small (< 2**-63).
        if (new Random().nextLong() == new Random().nextLong() ||
            new Random().nextLong() == new Random().nextLong())
            throw new RuntimeException("Random() seeds not unique.");
    }
}
Revision:	1.3
Committed:	Mon Feb 19 00:24:17 2007 UTC (17 years, 2 months ago) by dl
Branch:	MAIN
Changes since 1.2:	+7 -0 lines
Log Message:	Uniform headers
#	User	Rev	Content
1	jsr166	1.1	/**
2	jsr166	1.2	* @test %I% %E%
3	jsr166	1.1	* @bug 4949279
4			* @summary Independent instantiations of Random() have distinct seeds.
5			*/
6
7	dl	1.3	/*
8			* Written by Doug Lea with assistance from members of JCP JSR-166
9			* Expert Group and released to the public domain, as explained at
10			* http://creativecommons.org/licenses/publicdomain
11			*/
12
13
14	jsr166	1.1	import java.util.Random;
15
16			public class DistinctSeeds {
17			public static void main(String[] args) throws Exception {
18	jsr166	1.2	// Strictly speaking, it is possible for these to randomly fail,
19			// but the probability should be extremely small (< 2**-63).
20			if (new Random().nextLong() == new Random().nextLong() \|\|
21			new Random().nextLong() == new Random().nextLong())
22			throw new RuntimeException("Random() seeds not unique.");
23	jsr166	1.1	}
24			}