Android
java.util
public class

java.util.Random

java.lang.Object
java.util.Random Serializable

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

Known Direct Subclasses

Summary

Public Constructors

            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.

Public Methods

          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.
  synchronized        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(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).
          int  nextInt()
Generates a uniformly distributed 32-bit int value from the this random number sequence.
          long  nextLong()
Generates a uniformly distributed 64-bit int value from the this random number sequence.
  synchronized        void  setSeed(long seed)
Modifies the seed using linear congruential formula presented in The Art of Computer Programming, Volume 2, Section 3.2.1.

Protected Methods

  synchronized        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.
Methods inherited from class java.lang.Object

Details

Public Constructors

public Random()

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

See Also

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

Public Methods

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

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

public double nextDouble()

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

Returns

  • double

See Also

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

public synchronized 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

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

public int nextInt()

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

Returns

  • int uniformly distributed int value

public long nextLong()

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

Returns

  • 64-bit int random number

public synchronized 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

Protected Methods

protected synchronized 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
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