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23 
24 /*
25  * @test
26  * @summary Verify nextDouble stays within range
27  * @bug 8280550 8280950 8281183
28  */
29 
30 package test.java.util.Random;
31 
32 import java.util.SplittableRandom;
33 import java.util.random.RandomGenerator;
34 
35 public class RandomNextDoubleBoundary {
main(String... args)36     public static void main(String... args) {
37         negativeBounds();
38         positiveBounds();
39     }
40 
negativeBounds()41     private static void negativeBounds() {
42         // Both bounds are negative
43         double lowerBound = -1.0000000000000002;
44         double upperBound = -1.0;
45         var sr = new SplittableRandom(42L);
46         var r = sr.nextDouble(lowerBound, upperBound);
47 
48         if (r >= upperBound) {
49             System.err.println("r = " + r + "\t" + Double.toHexString(r));
50             System.err.println("ub = " + upperBound + "\t" + Double.toHexString(upperBound));
51             throw new RuntimeException("Greater than upper bound");
52         }
53 
54         if (r < lowerBound) {
55             System.err.println("r = " + r + "\t" + Double.toHexString(r));
56             System.err.println("lb = " + lowerBound + "\t" + Double.toHexString(lowerBound));
57             throw new RuntimeException("Less than lower bound");
58         }
59     }
60 
positiveBounds()61     private static void positiveBounds() {
62         double[][] originAndBounds = {{10, 100},
63                                       {12345, 123456},
64                                       {5432167.234, 54321678.1238}};
65         for (double[] originAndBound : originAndBounds) {
66             nextDoublesWithRange(originAndBound[0], originAndBound[1]);
67         }
68     }
69 
nextDoublesWithRange(double origin, double bound)70     public static void nextDoublesWithRange(double origin, double bound) {
71         RandomGenerator rg = new RandomGenerator() {
72             @Override
73             public double nextDouble() {
74                 return Double.MAX_VALUE;
75             }
76 
77             @Override
78             public long nextLong() {
79                 return 0;
80             }
81         };
82         double value = rg.nextDouble(origin, bound);
83 
84         if (bound > 0) {
85             value = rg.nextDouble(bound); // Equivalent to nextDouble(0.0, bound)
86             assertTrue(value >= 0.0);
87             assertTrue(value < bound);
88         }
89     }
90 
91     public static void assertTrue(boolean condition) {
92         if (!condition) {
93             throw new AssertionError();
94         }
95     }
96 }
97