org.apache.commons.lang.math

Class JVMRandom

java.lang.Object

java.util.Random

org.apache.commons.lang.math.JVMRandom

All Implemented Interfaces:

java.io.Serializable

public final class JVMRandom
extends java.util.Random

JVMRandom is a wrapper that supports all possible Random methods via the Math.random() method and its system-wide Random object.

It does this to allow for a Random class in which the seed is shared between all members of the class - a better name would have been SharedSeedRandom.

N.B. the current implementation overrides the methods Random.nextInt(int) and Random.nextLong() to produce positive numbers ranging from 0 (inclusive) to MAX_VALUE (exclusive).

Since:

2.0

Version:

$Id: JVMRandom.java 911986 2010-02-19 21:19:05Z niallp $

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
private boolean	constructed Ensures that only the parent constructor can call reseed.
private static long	serialVersionUID Required for serialization support.
private static java.util.Random	SHARED_RANDOM

Constructor Summary

Constructors

Constructor and Description
JVMRandom() Constructs a new instance.

Method Summary

Modifier and Type	Method and Description
private static int	bitsRequired(long num) Count the number of bits required to represent a long number.
private static long	next63bits() Get the next unsigned random long
boolean	nextBoolean() Returns the next pseudorandom, uniformly distributed boolean value from the Math.random() sequence.
void	nextBytes(byte[] byteArray) Unsupported in 2.0.
double	nextDouble() Synonymous to the Math.random() call.
float	nextFloat() Returns the next pseudorandom, uniformly distributed float value between 0.0 and 1.0 from the Math.random() sequence.
double	nextGaussian() Unsupported in 2.0.
int	nextInt() Returns the next pseudorandom, uniformly distributed int value from the Math.random() sequence.
int	nextInt(int n) Returns a pseudorandom, uniformly distributed int value between 0 (inclusive) and the specified value (exclusive), from the Math.random() sequence.
long	nextLong() Returns the next pseudorandom, uniformly distributed long value from the Math.random() sequence.
static long	nextLong(long n) Returns a pseudorandom, uniformly distributed long value between 0 (inclusive) and the specified value (exclusive), from the Math.random() sequence.
void	setSeed(long seed) Unsupported in 2.0.

Methods inherited from class java.util.Random

doubles, doubles, doubles, doubles, ints, ints, ints, ints, longs, longs, longs, longs, next

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

serialVersionUID

private static final long serialVersionUID

Required for serialization support.

See Also:

Serializable, Constant Field Values

SHARED_RANDOM

private static final java.util.Random SHARED_RANDOM

constructed

private boolean constructed

Ensures that only the parent constructor can call reseed.

Constructor Detail

JVMRandom

public JVMRandom()

Constructs a new instance.

Method Detail

setSeed

public void setSeed(long seed)

Unsupported in 2.0.

Overrides:

setSeed in class java.util.Random

Parameters:

seed - ignored

Throws:

java.lang.UnsupportedOperationException

nextGaussian

public double nextGaussian()

Unsupported in 2.0.

Overrides:

nextGaussian in class java.util.Random

Returns:

Nothing, this method always throws an UnsupportedOperationException.

Throws:

java.lang.UnsupportedOperationException

nextBytes

public void nextBytes(byte[] byteArray)

Unsupported in 2.0.

Overrides:

nextBytes in class java.util.Random

Parameters:

byteArray - ignored

Throws:

java.lang.UnsupportedOperationException

nextInt

public int nextInt()

Returns the next pseudorandom, uniformly distributed int value from the Math.random() sequence.

Identical to nextInt(Integer.MAX_VALUE)

N.B. All values are >= 0.

Overrides:

nextInt in class java.util.Random

Returns:

the random int

nextInt

public int nextInt(int n)

Returns a pseudorandom, uniformly distributed int value between 0 (inclusive) and the specified value (exclusive), from the Math.random() sequence.

Overrides:

nextInt in class java.util.Random

Parameters:

n - the specified exclusive max-value

Returns:

the random int

Throws:

java.lang.IllegalArgumentException - when n <= 0

nextLong

public long nextLong()

Returns the next pseudorandom, uniformly distributed long value from the Math.random() sequence.

Identical to nextLong(Long.MAX_VALUE)

N.B. All values are >= 0.

Overrides:

nextLong in class java.util.Random

Returns:

the random long

nextLong

public static long nextLong(long n)

Returns a pseudorandom, uniformly distributed long value between 0 (inclusive) and the specified value (exclusive), from the Math.random() sequence.

Parameters:

n - the specified exclusive max-value

Returns:

the random long

Throws:

java.lang.IllegalArgumentException - when n <= 0

nextBoolean

public boolean nextBoolean()

Returns the next pseudorandom, uniformly distributed boolean value from the Math.random() sequence.

Overrides:

nextBoolean in class java.util.Random

Returns:

the random boolean

nextFloat

public float nextFloat()

Returns the next pseudorandom, uniformly distributed float value between 0.0 and 1.0 from the Math.random() sequence.

Overrides:

nextFloat in class java.util.Random

Returns:

the random float

nextDouble

public double nextDouble()

Synonymous to the Math.random() call.

Overrides:

nextDouble in class java.util.Random

Returns:

the random double

next63bits

private static long next63bits()

Get the next unsigned random long

Returns:

unsigned random long

bitsRequired

private static int bitsRequired(long num)

Count the number of bits required to represent a long number.

Parameters:

num - long number

Returns:

number of bits required