Added in API level 35

RandomGenerator.JumpableGenerator

public static interface RandomGenerator.JumpableGenerator
implements RandomGenerator.StreamableGenerator

java.util.random.RandomGenerator.JumpableGenerator


This interface is designed to provide a common protocol for objects that generate pseudorandom values and can easily jump forward, by a moderate amount (ex. 264) to a distant point in the state cycle.

Ideally, all JumpableGenerator objects produced by iterative jumping from a single original JumpableGenerator object are statistically independent of one another and individually uniform. In practice, one must settle for some approximation to independence and uniformity. In particular, a specific implementation may assume that each generator in a stream produced by the jump() method is used to produce a number of values no larger than either 264 or the square root of its period. Implementors are advised to use algorithms whose period is at least 2127.

Methods are provided to perform a single jump operation and also to produce a stream of generators produced from the original by iterative copying and jumping of internal state. A typical strategy for a multithreaded application is to create a single JumpableGenerator object, calls its jump() method exactly once, and then parcel out generators from the resulting stream, one to each thread. It is generally not a good idea to call jump() on a generator that was itself produced by the jump() method, because the result may be a generator identical to another generator already produce by that call to the jump() method. For this reason, the return type of the jumps() method is Stream<RandomGenerator> rather than Stream<JumpableGenerator>, even though the actual generator objects in that stream likely do also implement the JumpableGenerator interface.

Objects that implement JumpableGenerator are typically not cryptographically secure. Consider instead using SecureRandom to get a cryptographically secure pseudo-random number generator for use by security-sensitive applications.

Summary

Public methods

abstract RandomGenerator.JumpableGenerator copy()

Returns a new generator whose internal state is an exact copy of this generator (therefore their future behavior should be identical if subjected to the same series of operations).

default RandomGenerator copyAndJump()

Copy this generator, jump this generator forward, then return the copy.

abstract void jump()

Alter the state of this pseudorandom number generator so as to jump forward a large, fixed distance (typically 264 or more) within its state cycle.

abstract double jumpDistance()

Returns the distance by which the jump() method will jump forward within the state cycle of this generator object.

default Stream<RandomGenerator> jumps(long streamSize)

Returns a stream producing the given streamSize number of new pseudorandom number generators, each of which implements the RandomGenerator interface.

default Stream<RandomGenerator> jumps()

Returns an effectively unlimited stream of new pseudorandom number generators, each of which implements the RandomGenerator interface.

static RandomGenerator.JumpableGenerator of(String name)

Returns an instance of JumpableGenerator that utilizes the name algorithm.

default Stream<RandomGenerator> rngs(long streamSize)

Returns a stream producing the given streamSize number of new pseudorandom number generators, each of which implements the RandomGenerator interface.

default Stream<RandomGenerator> rngs()

Returns an effectively unlimited stream of new pseudorandom number generators, each of which implements the RandomGenerator interface.

Inherited methods

Public methods

copy

Added in API level 35
public abstract RandomGenerator.JumpableGenerator copy ()

Returns a new generator whose internal state is an exact copy of this generator (therefore their future behavior should be identical if subjected to the same series of operations).

Returns
RandomGenerator.JumpableGenerator a new object that is a copy of this generator

copyAndJump

Added in API level 35
public RandomGenerator copyAndJump ()

Copy this generator, jump this generator forward, then return the copy.

Implementation Requirements:
  • The default implementation copies this, jumps and then returns the copy.
Returns
RandomGenerator a copy of this generator object before the jump occurred

jump

Added in API level 35
public abstract void jump ()

Alter the state of this pseudorandom number generator so as to jump forward a large, fixed distance (typically 264 or more) within its state cycle.

jumpDistance

Added in API level 35
public abstract double jumpDistance ()

Returns the distance by which the jump() method will jump forward within the state cycle of this generator object.

Returns
double the default jump distance (as a double value)

jumps

Added in API level 35
public Stream<RandomGenerator> jumps (long streamSize)

Returns a stream producing the given streamSize number of new pseudorandom number generators, each of which implements the RandomGenerator interface.

Implementation Requirements:
  • The default implementation produces a sequential stream that repeatedly calls copy() and jump() on this generator, and the copies become the generators produced by the stream.
Parameters
streamSize long: the number of generators to generate

Returns
Stream<RandomGenerator> a stream of objects that implement the RandomGenerator interface

Throws
IllegalArgumentException if streamSize is less than zero

jumps

Added in API level 35
public Stream<RandomGenerator> jumps ()

Returns an effectively unlimited stream of new pseudorandom number generators, each of which implements the RandomGenerator interface.

Implementation Note:
Implementation Requirements:
  • The default implementation produces a sequential stream that repeatedly calls copy() and jump() on this generator, and the copies become the generators produced by the stream.
Returns
Stream<RandomGenerator> a stream of objects that implement the RandomGenerator interface

of

Added in API level 35
public static RandomGenerator.JumpableGenerator of (String name)

Returns an instance of JumpableGenerator that utilizes the name algorithm.

Parameters
name String: Name of random number generator algorithm

Returns
RandomGenerator.JumpableGenerator An instance of JumpableGenerator

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

rngs

Added in API level 35
public Stream<RandomGenerator> rngs (long streamSize)

Returns a stream producing the given streamSize number of new pseudorandom number generators, each of which implements the RandomGenerator interface. Ideally the generators in the stream will appear to be statistically independent.

Implementation Requirements:
  • The default implementation calls jumps(streamSize).
Parameters
streamSize long: the number of generators to generate

Returns
Stream<RandomGenerator> a stream of objects that implement the RandomGenerator interface

Throws
IllegalArgumentException if streamSize is less than zero

rngs

Added in API level 35
public Stream<RandomGenerator> rngs ()

Returns an effectively unlimited stream of new pseudorandom number generators, each of which implements the RandomGenerator interface. Ideally the generators in the stream will appear to be statistically independent.

Implementation Requirements:
  • The default implementation calls jump().
Returns
Stream<RandomGenerator> a stream of objects that implement the RandomGenerator interface