THE PACKAGE JAVA.UTIL

java.util.Random

21.9

21.9.2

protected double nextNextGaussian;

A variable used by method

nextGaussian

 ( 21.9.12) to hold a precomputed

value to be delivered by that method the next time it is called.

21.9.3

protected boolean haveNextNextGaussian = false;

A variable used by method

nextGaussian

 ( 21.9.12) to keep track of whether it

has precomputed and stashed away the next value to be delivered by that method.

21.9.4

public Random()

This constructor initializes a newly created

Random

 number generator by using the

current time of day ( 20.18.6) as a seed.

public Random() { this(System.currentTimeMillis()); }

21.9.5

public Random(long seed)

This constructor initializes a newly created

Random

 number generator by using the

argument

seed

 as a seed.

public Random(long seed) { setSeed(seed); }

21.9.6

public void setSeed(long seed)

The general contract of

setSeed

 is that it alters the state of this random number

generator object so as to be in exactly the same state as if it had just been created

with the argument

seed

 as a seed.

The method

setSeed

 is implemented by class

Random

 as follows:

synchronized public void setSeed(long seed) {

this.seed = (seed ^ 0x5DEECE66DL) & ((1L << 48)   1);

haveNextNextGaussian = false;

}

The implementation of

setSeed

 by class

Random

 happens to use only 48 bits of

the given seed. In general, however, an overriding method may use all 64 bits of

the long argument as a seed value.

[In certain early versions of Java, the

setSeed

 method failed to reset the value

of

haveNextNextGaussian

 to

false

; this flaw could lead to failure to produce

repeatable behavior.]

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