Added in API level 35

RandomGenerator.LeapableGenerator

public static interface RandomGenerator.LeapableGenerator
implements RandomGenerator.JumpableGenerator

java.util.random.RandomGenerator.LeapableGenerator


This interface is designed to provide a common protocol for objects that generate sequences of pseudorandom values and can easily not only jump but also leap forward, by a large amount (ex. 2128), to a very distant point in the state cycle. Typically one will construct a series of LeapableGenerator objects by iterative leaping from a single original LeapableGenerator object, and then for each such object produce a subseries of objects by iterative jumping. There is little conceptual difference between leaping and jumping, but typically a leap will be a very long jump in the state cycle (perhaps distance 2128 or so).

Ideally, all LeapableGenerator objects produced by iterative leaping and jumping from a single original LeapableGenerator 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 leaps method is used to produce (by jumping) a number of objects no larger than 264. Implementors are advised to use algorithms whose period is at least 2191.

Methods are provided to perform a single leap operation and also to produce a stream of generators produced from the original by iterative copying and leaping of internal state. The generators produced must implement the JumpableGenerator interface but need not also implement the LeapableGenerator interface. A typical strategy for a multithreaded application is to create a single LeapableGenerator object, calls its leaps method exactly once, and then parcel out generators from the resulting stream, one to each thread. Then the jump() method of each such generator be called to produce a substream of generator objects.

Objects that implement LeapableGenerator 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.LeapableGenerator 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.JumpableGenerator copyAndLeap()

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

abstract void leap()

Alter the state of this pseudorandom number generator so as to leap forward a large, fixed distance (typically 296 or more) within its state cycle.

abstract double leapDistance()

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

default Stream<RandomGenerator.JumpableGenerator> leaps()

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

default Stream<RandomGenerator.JumpableGenerator> leaps(long streamSize)

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

static RandomGenerator.LeapableGenerator of(String name)

Returns an instance of LeapableGenerator that utilizes the name algorithm.

Inherited methods

Public methods

copy

Added in API level 35
public abstract RandomGenerator.LeapableGenerator 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.LeapableGenerator a new object that is a copy of this generator

copyAndLeap

Added in API level 35
public RandomGenerator.JumpableGenerator copyAndLeap ()

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

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

leap

Added in API level 35
public abstract void leap ()

Alter the state of this pseudorandom number generator so as to leap forward a large, fixed distance (typically 296 or more) within its state cycle.

leapDistance

Added in API level 35
public abstract double leapDistance ()

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

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

leaps

Added in API level 35
public Stream<RandomGenerator.JumpableGenerator> leaps ()

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

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

leaps

Added in API level 35
public Stream<RandomGenerator.JumpableGenerator> leaps (long streamSize)

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

Implementation Requirements:
  • The default implementation produces a sequential stream that repeatedly calls copy() and leap() 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.JumpableGenerator> a stream of objects that implement the JumpableGenerator interface

Throws
IllegalArgumentException if streamSize is less than zero

of

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

Returns an instance of LeapableGenerator that utilizes the name algorithm.

Parameters
name String: Name of random number generator algorithm

Returns
RandomGenerator.LeapableGenerator An instance of LeapableGenerator

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