com.pholser.junit.quickcheck.random

Class SourceOfRandomness

java.lang.Object

com.pholser.junit.quickcheck.random.SourceOfRandomness

public class SourceOfRandomness
extends Object

A source of randomness, fed to generators so they can produce random values for property parameters.

Constructor Summary

Constructors

Constructor and Description
SourceOfRandomness(Random delegate) Makes a new source of randomness.

Method Summary

Modifier and Type	Method and Description
<T> T	choose(Collection<T> items) Gives a random element of the given collection.
<T> T	choose(T[] items) Gives a random element of the given array.
BigInteger	nextBigInteger(int numberOfBits) Gives a random BigInteger representable by the given number of bits.
boolean	nextBoolean()
byte	nextByte(byte min, byte max) Gives a random byte value, uniformly distributed across the interval [min, max].
void	nextBytes(byte[] bytes)
byte[]	nextBytes(int count) Gives an array of a given length containing random bytes.
char	nextChar(char min, char max) Gives a random char value, uniformly distributed across the interval [min, max].
double	nextDouble()
double	nextDouble(double min, double max) Gives a random double value in the interval [min, max).
Duration	nextDuration(Duration min, Duration max) Gives a random Duration value, uniformly distributed across the interval [min, max].
float	nextFloat()
float	nextFloat(float min, float max) Gives a random float value in the interval [min, max).
double	nextGaussian()
Instant	nextInstant(Instant min, Instant max) Gives a random Instant value, uniformly distributed across the interval [min, max].
int	nextInt()
int	nextInt(int n)
int	nextInt(int min, int max) Gives a random int value, uniformly distributed across the interval [min, max].
long	nextLong()
long	nextLong(long min, long max) Gives a random long value, uniformly distributed across the interval [min, max].
short	nextShort(short min, short max) Gives a random short value, uniformly distributed across the interval [min, max].
long	seed()
void	setSeed(long seed)
Random	toJDKRandom() Gives a JDK source of randomness, with the same internal state as this source of randomness.

Methods inherited from class java.lang.Object

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

Constructor Detail

SourceOfRandomness

public SourceOfRandomness(Random delegate)

Makes a new source of randomness.

Parameters:

delegate - a JDK source of randomness, to which the new instance will delegate

Method Detail

toJDKRandom

public Random toJDKRandom()

Gives a JDK source of randomness, with the same internal state as this source of randomness.

Returns:

a JDK "clone" of self

nextBoolean

public boolean nextBoolean()

Returns:

a uniformly distributed boolean value

See Also:

Random.nextBoolean()

nextBytes

public void nextBytes(byte[] bytes)

Parameters:

bytes - a byte array to fill with random values

See Also:

Random.nextBytes(byte[])

nextBytes

public byte[] nextBytes(int count)

Gives an array of a given length containing random bytes.

Parameters:

count - the desired length of the random byte array

Returns:

random bytes

See Also:

Random.nextBytes(byte[])

nextDouble

public double nextDouble()

Returns:

a uniformly distributed random double value in the interval [0.0, 1.0)

See Also:

Random.nextDouble()

nextFloat

public float nextFloat()

Returns:

a uniformly distributed random float value in the interval [0.0, 1.0)

See Also:

Random.nextFloat()

nextGaussian

public double nextGaussian()

Returns:

a Gaussian-distributed random double value

See Also:

Random.nextGaussian()

nextInt

public int nextInt()

Returns:

a uniformly distributed random int value

See Also:

Random.nextInt()

nextInt

public int nextInt(int n)

Parameters:

n - upper bound

Returns:

a uniformly distributed random int value in the interval [0, n)

See Also:

Random.nextInt(int)

nextLong

public long nextLong()

Returns:

a uniformly distributed random long value

See Also:

Random.nextLong()

setSeed

public void setSeed(long seed)

Parameters:

seed - value with which to seed this source of randomness

See Also:

Random.setSeed(long)

seed

public long seed()

Returns:

the value used to initially seed this source of randomness

nextByte

public byte nextByte(byte min,
                     byte max)

Gives a random byte value, uniformly distributed across the interval [min, max].

Parameters:

min - lower bound of the desired interval

max - upper bound of the desired interval

Returns:

a random value

nextChar

public char nextChar(char min,
                     char max)

Gives a random char value, uniformly distributed across the interval [min, max].

Parameters:

min - lower bound of the desired interval

max - upper bound of the desired interval

Returns:

a random value

nextDouble

public double nextDouble(double min,
                         double max)

Gives a random double value in the interval [min, max).

This naive implementation takes a random double value from Random.nextDouble() and scales/shifts the value into the desired interval. This may give surprising results for large ranges.

Parameters:

min - lower bound of the desired interval

max - upper bound of the desired interval

Returns:

a random value

nextFloat

public float nextFloat(float min,
                       float max)

Gives a random float value in the interval [min, max).

This naive implementation takes a random float value from Random.nextFloat() and scales/shifts the value into the desired interval. This may give surprising results for large ranges.

Parameters:

min - lower bound of the desired interval

max - upper bound of the desired interval

Returns:

a random value

nextInt

public int nextInt(int min,
                   int max)

Gives a random int value, uniformly distributed across the interval [min, max].

Parameters:

min - lower bound of the desired interval

max - upper bound of the desired interval

Returns:

a random value

nextLong

public long nextLong(long min,
                     long max)

Gives a random long value, uniformly distributed across the interval [min, max].

Parameters:

min - lower bound of the desired interval

max - upper bound of the desired interval

Returns:

a random value

nextShort

public short nextShort(short min,
                       short max)

Gives a random short value, uniformly distributed across the interval [min, max].

Parameters:

min - lower bound of the desired interval

max - upper bound of the desired interval

Returns:

a random value

nextBigInteger

public BigInteger nextBigInteger(int numberOfBits)

Gives a random BigInteger representable by the given number of bits.

Parameters:

numberOfBits - the desired number of bits

Returns:

a random BigInteger

See Also:

BigInteger.BigInteger(int, java.util.Random)

nextInstant

public Instant nextInstant(Instant min,
                           Instant max)

Gives a random Instant value, uniformly distributed across the interval [min, max].

Parameters:

min - lower bound of the desired interval

max - upper bound of the desired interval

Returns:

a random value

nextDuration

public Duration nextDuration(Duration min,
                             Duration max)

Gives a random Duration value, uniformly distributed across the interval [min, max].

Parameters:

min - lower bound of the desired interval

max - upper bound of the desired interval

Returns:

a random value

choose

public <T> T choose(Collection<T> items)

Gives a random element of the given collection.

Type Parameters:

T - type of items in the collection

Parameters:

items - a collection

Returns:

a randomly chosen element from the collection

choose

public <T> T choose(T[] items)

Gives a random element of the given array.

Type Parameters:

T - type of items in the array

Parameters:

items - an array

Returns:

a randomly chosen element from the array