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)

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

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