Added in API level 35

Summary: Methods | Inherited Methods

RandomGeneratorFactory

public final class RandomGeneratorFactory
extends Object

java.lang.Object
↳	java.util.random.RandomGeneratorFactory<T extends java.util.random.RandomGenerator>

This is a factory class for generating multiple random number generators of a specific algorithm. RandomGeneratorFactory also provides methods for selecting random number generator algorithms. A specific RandomGeneratorFactory can be located by using the RandomGeneratorFactory#of(String) method, where the argument string is the name of the algorithm required. The method RandomGeneratorFactory#all() produces a non-empty Stream of all available RandomGeneratorFactorys that can be searched to locate a RandomGeneratorFactory suitable to the task. There are three methods for constructing a RandomGenerator instance, depending on the type of initial seed required. RandomGeneratorFactory#create(long) is used for long seed construction, RandomGeneratorFactory#create(byte[]) is used for byte[] seed construction, and RandomGeneratorFactory#create() is used for random seed construction. Example;

RandomGeneratorFactory<RandomGenerator> factory = RandomGeneratorFactory.of("Random");

     for (int i = 0; i < 10; i++) {
         new Thread(() -> {
             RandomGenerator random = factory.create(100L);
             System.out.println(random.nextDouble());
         }).start();
     }

RandomGeneratorFactory also provides methods describing the attributes (or properties) of a generator and can be used to select random number generator algorithms. These methods are typically used in conjunction with RandomGeneratorFactory#all(). In this example, the code locates the RandomGeneratorFactory that produces RandomGenerators with the highest number of state bits.

RandomGeneratorFactory<RandomGenerator> best = RandomGeneratorFactory.all()
         .sorted(Comparator.comparingInt(RandomGenerator::stateBits).reversed())
         .findFirst()
         .orElse(RandomGeneratorFactory.of("Random"));
     System.out.println(best.name() + " in " + best.group() + " was selected");

     RandomGenerator rng = best.create();
     System.out.println(rng.nextLong());

See also:

java.util.random

Summary

Public methods
`static Stream<RandomGeneratorFactory<RandomGenerator>>`	`all()` Returns a non-empty stream of available `RandomGeneratorFactory(s)`.
`T`	`create(byte[] seed)` Create an instance of `RandomGenerator` based on algorithm chosen providing a starting byte[] seed.
`T`	`create(long seed)` Create an instance of `RandomGenerator` based on algorithm chosen providing a starting long seed.
`T`	`create()` Create an instance of `RandomGenerator` based on algorithm chosen.
`int`	`equidistribution()` Returns the equidistribution of the algorithm.
`static RandomGeneratorFactory<RandomGenerator>`	`getDefault()` Returns a `RandomGeneratorFactory` meeting the minimal requirement of having an algorithm whose state bits are greater than or equal 64.
`String`	`group()` Return the group name of the algorithm used by the random number generator.
`boolean`	`isArbitrarilyJumpable()` Return true if random generator can jump an arbitrarily specified distant point in the state cycle.
`boolean`	`isDeprecated()` Return true if the implementation of RandomGenerator (algorithm) has been marked for deprecation.
`boolean`	`isHardware()` Return true if random generator uses a hardware device (HRNG) to produce entropic input.
`boolean`	`isJumpable()` Return true if random generator can jump a specified distant point in the state cycle.
`boolean`	`isLeapable()` Return true if random generator is jumpable and can leap to a very distant point in the state cycle.
`boolean`	`isSplittable()` Return true if random generator can be cloned into a separate object with the same properties but positioned further in the state cycle.
`boolean`	`isStatistical()` Return true if random generator is computed using an arithmetic algorithm and is statistically deterministic.
`boolean`	`isStochastic()` Return true if random generator is computed using external or entropic sources as inputs.
`boolean`	`isStreamable()` Return true if random generator can be used to create `Streams` of random numbers.
`String`	`name()` Return the name of the algorithm used by the random number generator.
`static <T extends RandomGenerator> RandomGeneratorFactory<T>`	`of(String name)` Returns a `RandomGeneratorFactory` that can produce instances of `RandomGenerator` that utilize the `name` algorithm.
`BigInteger`	`period()` Return the period of the algorithm used by the random number generator.
`int`	`stateBits()` Returns number of bits used by the algorithm to maintain state of seed.

Inherited methods

From class


        
          java.lang.Object

`Object`	`clone()` Creates and returns a copy of this object.
`boolean`	`equals(Object obj)` Indicates whether some other object is "equal to" this one.
`void`	`finalize()` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
`final Class<?>`	`getClass()` Returns the runtime class of this `Object`.
`int`	`hashCode()` Returns a hash code value for the object.
`final void`	`notify()` Wakes up a single thread that is waiting on this object's monitor.
`final void`	`notifyAll()` Wakes up all threads that are waiting on this object's monitor.
`String`	`toString()` Returns a string representation of the object.
`final void`	`wait(long timeoutMillis, int nanos)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait(long timeoutMillis)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait()` Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

Public methods

all

Added in API level 35

public static Stream<RandomGeneratorFactory<RandomGenerator>> all ()

Returns a non-empty stream of available RandomGeneratorFactory(s). RandomGenerators that are marked as deprecated are not included in the result.

Implementation Requirements:

Availability is determined by RandomGeneratorFactory using the service provider API to locate implementations of the RandomGenerator interface.

Returns
`Stream<RandomGeneratorFactory<RandomGenerator>>`	a non-empty stream of all available `RandomGeneratorFactory(s)`.

create

Added in API level 35

public T create (byte[] seed)

Create an instance of RandomGenerator based on algorithm chosen providing a starting byte[] seed. If byte[] seed is not supported by an algorithm then the no argument form of create is used.

Parameters
`seed`	`byte`: byte array random seed value.

Returns
`T`	new in instance of `RandomGenerator`.

Throws
`NullPointerException`	if seed is null.

create

Added in API level 35

public T create (long seed)

Create an instance of RandomGenerator based on algorithm chosen providing a starting long seed. If long seed is not supported by an algorithm then the no argument form of create is used.

Parameters
`seed`	`long`: long random seed value.

Returns
`T`	new in instance of `RandomGenerator`.

create

Added in API level 35

public T create ()

Create an instance of RandomGenerator based on algorithm chosen.

Returns
`T`	new in instance of `RandomGenerator`.

equidistribution

Added in API level 35

public int equidistribution ()

Returns the equidistribution of the algorithm.

Returns
`int`	the equidistribution of the algorithm.

getDefault

Added in API level 35

public static RandomGeneratorFactory<RandomGenerator> getDefault ()

Returns a RandomGeneratorFactory meeting the minimal requirement of having an algorithm whose state bits are greater than or equal 64.

Implementation Requirements:

Since algorithms will improve over time, there is no guarantee that this method will return the same algorithm over time.

Returns
`RandomGeneratorFactory<RandomGenerator>`	a `RandomGeneratorFactory`

group

Added in API level 35

public String group ()

Return the group name of the algorithm used by the random number generator.

Returns
`String`	Group name of the algorithm.

isArbitrarilyJumpable

Added in API level 35

public boolean isArbitrarilyJumpable ()

Return true if random generator can jump an arbitrarily specified distant point in the state cycle.

Returns
`boolean`	true if random generator is arbitrarily jumpable.

isDeprecated

Added in API level 35

public boolean isDeprecated ()

Return true if the implementation of RandomGenerator (algorithm) has been marked for deprecation.

Implementation Note:

Random number generator algorithms evolve over time; new algorithms will be introduced and old algorithms will lose standing. If an older algorithm is deemed unsuitable for continued use, it will be marked as deprecated to indicate that it may be removed at some point in the future.

Returns
`boolean`	true if the implementation of RandomGenerator (algorithm) has been marked for deprecation

isHardware

Added in API level 35

public boolean isHardware ()

Return true if random generator uses a hardware device (HRNG) to produce entropic input.

Returns
`boolean`	true if random generator is generated by hardware.

isJumpable

Added in API level 35

public boolean isJumpable ()

Return true if random generator can jump a specified distant point in the state cycle.

Returns
`boolean`	true if random generator is jumpable.

isLeapable

Added in API level 35

public boolean isLeapable ()

Return true if random generator is jumpable and can leap to a very distant point in the state cycle.

Returns
`boolean`	true if random generator is leapable.

isSplittable

Added in API level 35

public boolean isSplittable ()

Return true if random generator can be cloned into a separate object with the same properties but positioned further in the state cycle.

Returns
`boolean`	true if random generator is splittable.

isStatistical

Added in API level 35

public boolean isStatistical ()

Return true if random generator is computed using an arithmetic algorithm and is statistically deterministic.

Returns
`boolean`	true if random generator is statistical.

isStochastic

Added in API level 35

public boolean isStochastic ()

Return true if random generator is computed using external or entropic sources as inputs.

Returns
`boolean`	true if random generator is stochastic.

isStreamable

Added in API level 35

public boolean isStreamable ()

Return true if random generator can be used to create Streams of random numbers.

Returns
`boolean`	true if random generator is streamable.

name

Added in API level 35

public String name ()

Return the name of the algorithm used by the random number generator.

Returns
`String`	Name of the algorithm.

of

Added in API level 35

public static RandomGeneratorFactory<T> of (String name)

Returns a RandomGeneratorFactory that can produce instances of RandomGenerator that utilize the name algorithm.

Implementation Requirements:

Availability is determined by RandomGeneratorFactory using the service provider API to locate implementations of the RandomGenerator interface.

Parameters
`name`	`String`: Name of random number generator algorithm

Returns
`RandomGeneratorFactory<T>`	`RandomGeneratorFactory` of `RandomGenerator`

Throws
`NullPointerException`	if name is null
`IllegalArgumentException`	if the named algorithm is not found

period

Added in API level 35

public BigInteger period ()

Return the period of the algorithm used by the random number generator. Returns BigInteger.ZERO if period is not determinable.

Returns
`BigInteger`	BigInteger period.

stateBits

Added in API level 35

public int stateBits ()

Returns number of bits used by the algorithm to maintain state of seed.

Returns
`int`	number of bits used by the algorithm to maintain state of seed.