java.util
Class Random

java.lang.Object
  java.util.Random

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

SecureRandom

public class Random
extends Object
implements Serializable

This class provides methods that generates pseudo-random numbers of different types, such as int, long, double and float using either

See Also:

Properties, PropertyResourceBundle, Serialized Form

Field Summary

(package private) boolean	haveNextNextGaussian The boolean value indicating if the second Gaussian number is available.
(package private) static long	multiplier
(package private) double	nextNextGaussian The second Gaussian generated number.
(package private) long	seed

Constructor Summary

Random()
Construct a random generator with the current time of day in milliseconds as the initial state.

Random(long seed)
Construct a random generator with the given seed as the initial state.

Method Summary

protected int	next(int bits) Returns a pseudo-random uniformly distributed int value of the number of bits specified by the argument bits as described by Donald E.
boolean	nextBoolean() Returns the next pseudo-random, uniformly distributed boolean value generated by this generator.
void	nextBytes(byte[] buf) Modifies the byte array by a random sequence of bytes generated by this random number generator.
double	nextDouble() Generates a normally distributed random double number between 0.0 inclusively and 1.0 exclusively.
float	nextFloat() Generates a normally distributed random float number between 0.0 inclusively and 1.0 exclusively.
double	nextGaussian() pseudo-randomly generates (approximately) a normally distributed double value with mean 0.0 and a standard deviation value of 1.0 using the polar method of G.
int	nextInt() Generates a uniformly distributed 32-bit int value from the this random number sequence.
int	nextInt(int n) Returns to the caller a new pseudo-random integer value which is uniformly distributed between 0 (inclusively) and the value of n (exclusively).
long	nextLong() Generates a uniformly distributed 64-bit int value from the this random number sequence.
void	setSeed(long seed) Modifies the seed using linear congruential formula presented in The Art of Computer Programming, Volume 2, Section 3.2.1.

Methods inherited from class java.lang.Object

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

Field Detail

multiplier

static final long multiplier

See Also:

Constant Field Values

haveNextNextGaussian

boolean haveNextNextGaussian

The boolean value indicating if the second Gaussian number is available.

seed

long seed

nextNextGaussian

double nextNextGaussian

The second Gaussian generated number.

Constructor Detail

Random

public Random()

Construct a random generator with the current time of day in milliseconds as the initial state.

See Also:

setSeed(long)

Random

public Random(long seed)

Construct a random generator with the given seed as the initial state.

Parameters:

seed - the seed that will determine the initial state of this random number generator

See Also:

setSeed(long)

Method Detail

next

protected int next(int bits)

Returns a pseudo-random uniformly distributed int value of the number of bits specified by the argument bits as described by Donald E. Knuth in The Art of Computer Programming, Volume 2: Seminumerical Algorithms, section 3.2.1.

Parameters:

bits - number of bits of the returned value

Returns:

int a pseudo-random generated int number

See Also:

nextBytes(byte[]), nextDouble(), nextFloat(), nextInt(), nextInt(int), nextGaussian(), nextLong()

nextBoolean

public boolean nextBoolean()

Returns the next pseudo-random, uniformly distributed boolean value generated by this generator.

Returns:

boolean a pseudo-random, uniformly distributed boolean value

nextBytes

public void nextBytes(byte[] buf)

Modifies the byte array by a random sequence of bytes generated by this random number generator.

Parameters:

buf - non-null array to contain the new random bytes

See Also:

next(int)

nextDouble

public double nextDouble()

Generates a normally distributed random double number between 0.0 inclusively and 1.0 exclusively.

Returns:

double

See Also:

nextFloat()

nextFloat

public float nextFloat()

Generates a normally distributed random float number between 0.0 inclusively and 1.0 exclusively.

Returns:

float a random float number between 0.0 and 1.0

See Also:

nextDouble()

nextGaussian

public double nextGaussian()

pseudo-randomly generates (approximately) a normally distributed double value with mean 0.0 and a standard deviation value of 1.0 using the polar method of G. E. P. Box, M. E. Muller, and G. Marsaglia, as described by Donald E. Knuth in The Art of Computer Programming, Volume 2: Seminumerical Algorithms, section 3.4.1, subsection C, algorithm P

Returns:

double

See Also:

nextDouble()

nextInt

public int nextInt()

Generates a uniformly distributed 32-bit int value from the this random number sequence.

Returns:

int uniformly distributed int value

See Also:

Integer.MAX_VALUE, Integer.MIN_VALUE, next(int), nextLong()

nextInt

public int nextInt(int n)

Returns to the caller a new pseudo-random integer value which is uniformly distributed between 0 (inclusively) and the value of n (exclusively).

Parameters:

n - int

Returns:

int

nextLong

public long nextLong()

Generates a uniformly distributed 64-bit int value from the this random number sequence.

Returns:

64-bit int random number

See Also:

Integer.MAX_VALUE, Integer.MIN_VALUE, next(int), nextInt(), nextInt(int)

setSeed

public void setSeed(long seed)

Modifies the seed using linear congruential formula presented in The Art of Computer Programming, Volume 2, Section 3.2.1.

Parameters:

seed - the seed that alters the state of the random number generator

See Also:

next(int), Random(), Random(long)