1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
|
/*
* Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package jdk.testlibrary;
import java.util.Random;
import java.util.SplittableRandom;
/**
* Factory class which generates and prints to STDOUT a long-valued seed
* for use in initializing a PRNG. An instance of {@code Random} or
* {@code SplittableRandom} may likewise be obtained.
*/
public class RandomFactory {
/**
* Attempt to obtain the seed from the value of the "seed" property.
* @return The seed or {@code null} if the "seed" property was not set or
* could not be parsed.
*/
private static Long getSystemSeed() {
Long seed = null;
try {
// note that Long.valueOf(null) also throws a
// NumberFormatException so if the property is undefined this
// will still work correctly
seed = Long.valueOf(System.getProperty("seed"));
} catch (NumberFormatException e) {
// do nothing: seed is still null
}
return seed;
}
/**
* Obtain a seed from an independent PRNG.
*
* @return A random seed.
*/
private static long getRandomSeed() {
return new Random().nextLong();
}
/**
* Obtain and print to STDOUT a seed appropriate for initializing a PRNG.
* If the system property "seed" is set and has value which may be correctly
* parsed it is used, otherwise a seed is generated using an independent
* PRNG.
*
* @return The seed.
*/
public static long getSeed() {
Long seed = getSystemSeed();
if (seed == null) {
seed = getRandomSeed();
}
System.out.println("Seed from RandomFactory = "+seed+"L");
return seed;
}
/**
* Obtain and print to STDOUT a seed and use it to initialize a new
* {@code Random} instance which is returned. If the system
* property "seed" is set and has value which may be correctly parsed it
* is used, otherwise a seed is generated using an independent PRNG.
*
* @return The {@code Random} instance.
*/
public static Random getRandom() {
return new Random(getSeed());
}
/**
* Obtain and print to STDOUT a seed and use it to initialize a new
* {@code SplittableRandom} instance which is returned. If the system
* property "seed" is set and has value which may be correctly parsed it
* is used, otherwise a seed is generated using an independent PRNG.
*
* @return The {@code SplittableRandom} instance.
*/
public static SplittableRandom getSplittableRandom() {
return new SplittableRandom(getSeed());
}
}
|
