Added in API level 35

RandomGenerator.ArbitrarilyJumpableGenerator

public static interface RandomGenerator.ArbitrarilyJumpableGenerator
implements RandomGenerator.LeapableGenerator

java.util.random.RandomGenerator.ArbitrarilyJumpableGenerator


This interface is designed to provide a common protocol for objects that generate sequences of pseudorandom values and can easily jump forward, by an arbitrary amount, to a distant point in the state cycle.

Ideally, all ArbitrarilyJumpableGenerator objects produced by iterative jumping from a single original ArbitrarilyJumpableGenerator object are statistically independent of one another and individually uniform, provided that they do not traverse overlapping portions of the state cycle. 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 the jump distance specified. Implementors are advised to use algorithms whose period is at least 2127.

For many applications, it suffices to jump forward by a power of two or some small multiple of a power of two, but this power of two may not be representable as a long value. To avoid the use of BigInteger values as jump distances, double values are used instead.

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 ArbitrarilyJumpableGenerator object, call its jump() method exactly once, and then parcel out generators from the resulting stream, one to each thread. However, each generator produced also has type ArbitrarilyJumpableGenerator; with care, different jump distances can be used to traverse the entire state cycle in various ways.

Objects that implement ArbitrarilyJumpableGenerator 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.ArbitrarilyJumpableGenerator 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.ArbitrarilyJumpableGenerator copyAndJump(double distance)

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

default 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 void jump(double distance)

Alter the state of this pseudorandom number generator so as to jump forward a specified distance within its state cycle.

abstract void jumpPowerOfTwo(int logDistance)

Alter the state of this pseudorandom number generator so as to jump forward a distance equal to 2logDistance within its state cycle.

default Stream<RandomGenerator.ArbitrarilyJumpableGenerator> jumps(long streamSize, double distance)

Returns a stream producing the given streamSize number of new pseudorandom number generators, each of which implements the ArbitrarilyJumpableGenerator interface, produced by jumping copies of this generator by different integer multiples of the specified jump distance.

default Stream<RandomGenerator.ArbitrarilyJumpableGenerator> jumps(double distance)

Returns an effectively unlimited stream of new pseudorandom number generators, each of which implements the ArbitrarilyJumpableGenerator interface, produced by jumping copies of this generator by different integer multiples of the specified jump distance.

default void leap()

Alter the state of this pseudorandom number generator so as to jump forward a very large, fixed distance (typically 2128 or more) within its state cycle.

static RandomGenerator.ArbitrarilyJumpableGenerator of(String name)

Returns an instance of ArbitrarilyJumpableGenerator that utilizes the name algorithm.

Inherited methods

Public methods

copy

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

copyAndJump

Added in API level 35
public RandomGenerator.ArbitrarilyJumpableGenerator copyAndJump (double distance)

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

Implementation Requirements:
  • The default implementation copies this, jumps(distance) and then returns the copy.
Parameters
distance double: a distance to jump forward within the state cycle

Returns
RandomGenerator.ArbitrarilyJumpableGenerator a copy of this generator object before the jump occurred

Throws
IllegalArgumentException if distance is not greater than or equal to 0.0, or is greater than the period of this generator

jump

Added in API level 35
public 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. The distance used is that returned by method jumpDistance().

Implementation Requirements:
  • The default implementation invokes jump(jumpDistance()).

jump

Added in API level 35
public abstract void jump (double distance)

Alter the state of this pseudorandom number generator so as to jump forward a specified distance within its state cycle.

Parameters
distance double: the distance to jump forward within the state cycle

Throws
IllegalArgumentException if distance is not greater than or equal to 0.0, or is greater than the period of this generator

jumpPowerOfTwo

Added in API level 35
public abstract void jumpPowerOfTwo (int logDistance)

Alter the state of this pseudorandom number generator so as to jump forward a distance equal to 2logDistance within its state cycle.

Parameters
logDistance int: the base-2 logarithm of the distance to jump forward within the state cycle

Throws
IllegalArgumentException if logDistance is 2logDistance is greater than the period of this generator

jumps

Added in API level 35
public Stream<RandomGenerator.ArbitrarilyJumpableGenerator> jumps (long streamSize, 
                double distance)

Returns a stream producing the given streamSize number of new pseudorandom number generators, each of which implements the ArbitrarilyJumpableGenerator interface, produced by jumping copies of this generator by different integer multiples of the specified jump distance.

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

distance double: a distance to jump forward within the state cycle

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

Throws
IllegalArgumentException if streamSize is less than zero or if distance is not greater than or equal to 0.0, or is greater than the period of this generator

jumps

Added in API level 35
public Stream<RandomGenerator.ArbitrarilyJumpableGenerator> jumps (double distance)

Returns an effectively unlimited stream of new pseudorandom number generators, each of which implements the ArbitrarilyJumpableGenerator interface, produced by jumping copies of this generator by different integer multiples of the specified jump distance.

Implementation Requirements:
Parameters
distance double: a distance to jump forward within the state cycle

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

Throws
IllegalArgumentException if distance is not greater than or equal to 0.0, or is greater than the period of this generator

leap

Added in API level 35
public void leap ()

Alter the state of this pseudorandom number generator so as to jump forward a very large, fixed distance (typically 2128 or more) within its state cycle. The distance used is that returned by method leapDistance().

of

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

Returns an instance of ArbitrarilyJumpableGenerator that utilizes the name algorithm.

Parameters
name String: Name of random number generator algorithm

Returns
RandomGenerator.ArbitrarilyJumpableGenerator An instance of ArbitrarilyJumpableGenerator

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