squidpony.squidmath

Class StatefulRNG

java.lang.Object

squidpony.squidmath.AbstractRNG

squidpony.squidmath.RNG

squidpony.squidmath.StatefulRNG

All Implemented Interfaces:

java.io.Serializable, IRNG, IStatefulRNG, RandomnessSource, StatefulRandomness

Direct Known Subclasses:

DeckRNG, EditRNG

public class StatefulRNG
extends RNG
implements java.io.Serializable, IStatefulRNG

A slight variant on RNG that always uses a stateful RandomessSource and so can have its state set or retrieved using setState() or getState(). Created by Tommy Ettinger on 9/15/2015.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class squidpony.squidmath.RNG

RNG.CustomRandom

Field Summary

Fields inherited from class squidpony.squidmath.RNG

ran, random

Constructor Summary

Constructors

Constructor and Description
StatefulRNG()
StatefulRNG(java.lang.CharSequence seedString) String-seeded constructor uses the hash of the String as a seed for DiverRNG, which is of high quality, but low period (which rarely matters for games), and has good speed and tiny state size.
StatefulRNG(long seed) Seeded constructor uses DiverRNG, which is of high quality, but low period (which rarely matters for games), and has good speed and tiny state size.
StatefulRNG(RandomnessSource random)

Method Summary

Modifier and Type	Method and Description
StatefulRNG	copy() Creates a copy of this StatefulRNG; it will generate the same random numbers, given the same calls in order, as this StatefulRNG at the point copy() is called.
long	getState() Get a long that can be used to reproduce the sequence of random numbers this object will generate starting now.
void	setRandomness(RandomnessSource random)
void	setState(long state) Sets the state of the random number generator to a given long, which will alter future random numbers this produces based on the state.
java.io.Serializable	toSerializable() Returns this StatefulRNG in a way that can be deserialized even if only IRNG's methods can be called.
java.lang.String	toString()

Methods inherited from class squidpony.squidmath.RNG

approximateBits, asRandom, betweenWeighted, equals, getRandomCellsIterable, getRandomElement, getRandomness, getRandomStartIterable, getRandomUniqueCells, getRandomUniqueCells, getRandomUniqueCells, hashCode, maxDoubleOf, maxFloatOf, maxIntOf, maxLongOf, minDoubleOf, minFloatOf, minIntOf, minLongOf, next, nextBoolean, nextBytes, nextCoord, nextCurvedFloat, nextDouble, nextDoubleInclusive, nextDoubleInclusive, nextFloat, nextFloatInclusive, nextFloatInclusive, nextInt, nextIntHasty, nextLong, randomInterleave, randomOrdering, randomOrdering, randomPortion, randomPortion, randomRange, randomRotation, shuffle, shuffle, shuffle, shuffle, shuffleInPlace, shuffleInPlace

Methods inherited from class squidpony.squidmath.AbstractRNG

between, between, between, getRandomElement, getRandomElement, nextDouble, nextFloat, nextInt, nextLong, nextSignedInt, nextSignedLong, swap

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface squidpony.squidmath.IRNG

between, between, between, getRandomElement, getRandomElement, getRandomElement, next, nextBoolean, nextDouble, nextDouble, nextFloat, nextFloat, nextInt, nextInt, nextLong, nextLong, nextSignedInt, nextSignedLong, randomOrdering, randomOrdering, randomPortion, shuffle, shuffle, shuffle, shuffle, shuffleInPlace, shuffleInPlace

Constructor Detail

StatefulRNG

public StatefulRNG()

StatefulRNG

public StatefulRNG(RandomnessSource random)

StatefulRNG

public StatefulRNG(long seed)

Seeded constructor uses DiverRNG, which is of high quality, but low period (which rarely matters for games), and has good speed and tiny state size.

StatefulRNG

public StatefulRNG(java.lang.CharSequence seedString)

String-seeded constructor uses the hash of the String as a seed for DiverRNG, which is of high quality, but low period (which rarely matters for games), and has good speed and tiny state size. Note: This constructor changed behavior on April 22, 2017, again on December 23, 2017, and again on June 14, 2018. The first was when it was noticed that it was not seeding very effectively (only assigning to 32 bits of seed instead of all 64). The older behavior isn't fully preserved, since it used a rather low-quality String hashing algorithm and so probably had problems producing good starting seeds, but you can get close by replacing new StatefulRNG(text) with new StatefulRNG(new LightRNG(CrossHash.hash(text))). The new technique assigns to all 64 bits and has less correlation between similar inputs causing similar starting states. It's also faster, but that shouldn't matter in a constructor. It uses a better hashing algorithm because CrossHash no longer has the older, worse one. The latest change in June switched to DiverRNG instead of LightRNG.

Method Detail

setRandomness

public void setRandomness(RandomnessSource random)

Overrides:

setRandomness in class RNG

copy

public StatefulRNG copy()

Creates a copy of this StatefulRNG; it will generate the same random numbers, given the same calls in order, as this StatefulRNG at the point copy() is called. The copy will not share references with this StatefulRNG.

Specified by:

copy in interface RandomnessSource

Specified by:

copy in interface StatefulRandomness

Overrides:

copy in class RNG

Returns:

a copy of this StatefulRNG

getState

public long getState()

Get a long that can be used to reproduce the sequence of random numbers this object will generate starting now.

Specified by:

getState in interface StatefulRandomness

Returns:

a long that can be used as state.

setState

public void setState(long state)

Sets the state of the random number generator to a given long, which will alter future random numbers this produces based on the state.

Specified by:

setState in interface StatefulRandomness

Parameters:

state - a long, which typically should not be 0 (some implementations may tolerate a state of 0, however).

toString

public java.lang.String toString()

Overrides:

toString in class RNG

toSerializable

public java.io.Serializable toSerializable()

Returns this StatefulRNG in a way that can be deserialized even if only IRNG's methods can be called.

Specified by:

toSerializable in interface IRNG

Overrides:

toSerializable in class RNG

Returns:

a Serializable view of this StatefulRNG; always this