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
#	Content
1	/**
2	* @test %I% %E%
3	* @bug 4949279
4	* @summary Independent instantiations of Random() have distinct seeds.
5	*/
6
7	/*
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	import java.util.Random;
15
16	public class DistinctSeeds {
17	public static void main(String[] args) throws Exception {
18	// 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	}
24	}