Class java.util.Random - JDK 5 Documentation v1.1.8, Java 2 SDK 英文文档

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Class java.util.Random

java.lang.Object
   |
   +----java.util.Random

public class Random
extends Object
implements Serializable

An instance of this class is used to generate a stream of pseudorandom numbers. The class uses a 48-bit seed, which is modified using a linear congruential formula. (See Donald Knuth, The Art of Computer Programming, Volume 2, Section 3.2.1.)

If two instances of Random are created with the same seed, and the same sequence of method calls is made for each, they will generate and return identical sequences of numbers.

Many applications will find the random method in class Math simpler to use.

See Also:: random

Random(): Creates a new random number generator.
Random(long): Creates a new random number generator using a single long seed.

next(int): Generates the next pseudorandom number.
nextBytes(byte[]): Generates a user specified number of random bytes.
nextDouble(): Returns the next pseudorandom, uniformly distributed double value between 0.0 and 1.0 from this random number generator's sequence.
nextFloat(): Returns the next pseudorandom, uniformly distributed float value between 0.0 and 1.0 from this random number generator's sequence.
nextGaussian(): Returns the next pseudorandom, Gaussian ("normally") distributed double value with mean 0.0 and standard deviation 1.0 from this random number generator's sequence.
nextInt(): Returns the next pseudorandom, uniformly distributed int value from this random number generator's sequence.
nextLong(): Returns the next pseudorandom, uniformly distributed long value from this random number generator's sequence.
setSeed(long): Sets the seed of this random number generator using a single long seed.

Random

 public Random()

Creates a new random number generator. Its seed is initialized to a value based on the current time.

See Also:: currentTimeMillis

Random

 public Random(long seed)

Creates a new random number generator using a single long seed.

Parameters:: seed - the initial seed.
See Also:: setSeed

setSeed

 public synchronized void setSeed(long seed)

Sets the seed of this random number generator using a single long seed.

Parameters:: seed - the initial seed.

next

 protected synchronized int next(int bits)

Generates the next pseudorandom number. Subclass should override this, as this is used by all other methods.

Parameters:: bits - random bits
Returns:: the next pseudorandom value from this random number generator's sequence.

nextBytes

 public void nextBytes(byte bytes[])

Generates a user specified number of random bytes.

nextInt

 public int nextInt()

Returns the next pseudorandom, uniformly distributed int value from this random number generator's sequence.

Returns:: the next pseudorandom, uniformly distributed int value from this random number generator's sequence.

nextLong

 public long nextLong()

Returns the next pseudorandom, uniformly distributed long value from this random number generator's sequence.

Returns:: the next pseudorandom, uniformly distributed long value from this random number generator's sequence.

nextFloat

 public float nextFloat()

Returns the next pseudorandom, uniformly distributed float value between 0.0 and 1.0 from this random number generator's sequence.

Returns:: the next pseudorandom, uniformly distributed float value between 0.0 and 1.0 from this random number generator's sequence.

nextDouble

 public double nextDouble()

Returns the next pseudorandom, uniformly distributed double value between 0.0 and 1.0 from this random number generator's sequence.

Returns:: the next pseudorandom, uniformly distributed double value between 0.0 and 1.0 from this random number generator's sequence.

nextGaussian

 public synchronized double nextGaussian()

Returns the next pseudorandom, Gaussian ("normally") distributed double value with mean 0.0 and standard deviation 1.0 from this random number generator's sequence.

Returns:: the next pseudorandom, Gaussian ("normally") distributed double value with mean 0.0 and standard deviation 1.0 from this random number generator's sequence.

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