Class ISAACRandom
- All Implemented Interfaces:
Serializable
,RandomGenerator
ISAAC (Indirection, Shift, Accumulate, Add, and Count) generates 32-bit random numbers. ISAAC has been designed to be cryptographically secure and is inspired by RC4. Cycles are guaranteed to be at least 240 values long, and they are 28295 values long on average. The results are uniformly distributed, unbiased, and unpredictable unless you know the seed.
This code is based (with minor changes and improvements) on the original implementation of the algorithm by Bob Jenkins.
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Constructor Summary
ConstructorDescriptionCreates a new ISAAC random number generator.ISAACRandom
(int[] seed) Creates a new ISAAC random number generator using an int array seed.ISAACRandom
(long seed) Creates a new ISAAC random number generator using a single long seed. -
Method Summary
Modifier and TypeMethodDescriptionprotected void
Clears the cache used by the default implementation ofRandomGenerator.nextGaussian()
.boolean
Returns the next pseudorandom, uniformly distributedboolean
value from this random number generator's sequence.void
nextBytes
(byte[] bytes) Generates random bytes and places them into a user-supplied byte array.void
nextBytes
(byte[] bytes, int start, int len) Generates random bytes and places them into a user-supplied byte array.double
Returns the next pseudorandom, uniformly distributeddouble
value between0.0
and1.0
from this random number generator's sequence.float
Returns the next pseudorandom, uniformly distributedfloat
value between0.0
and1.0
from this random number generator's sequence.double
Returns the next pseudorandom, Gaussian ("normally") distributeddouble
value with mean0.0
and standard deviation1.0
from this random number generator's sequence.int
nextInt()
Returns the next pseudorandom, uniformly distributedint
value from this random number generator's sequence.int
nextInt
(int n) Returns a pseudorandom, uniformly distributedint
value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence.long
nextLong()
Returns the next pseudorandom, uniformly distributedlong
value from this random number generator's sequence.long
nextLong
(long n) Returns a pseudorandom, uniformly distributedint
value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence.void
setSeed
(int seed) Sets the seed of the underlying random number generator using anint
seed.void
setSeed
(int[] seed) Sets the seed of the underlying random number generator using anint
array seed.void
setSeed
(long seed) Sets the seed of the underlying random number generator using along
seed.toString()
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Constructor Details
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ISAACRandom
public ISAACRandom()Creates a new ISAAC random number generator.
The instance is initialized using a combination of the current time and system hash code of the instance as the seed. -
ISAACRandom
public ISAACRandom(long seed) Creates a new ISAAC random number generator using a single long seed.- Parameters:
seed
- Initial seed.
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ISAACRandom
public ISAACRandom(int[] seed) Creates a new ISAAC random number generator using an int array seed.- Parameters:
seed
- Initial seed. Ifnull
, the seed will be related to the current time.
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Method Details
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setSeed
public void setSeed(int[] seed) Sets the seed of the underlying random number generator using anint
array seed.Sequences of values generated starting with the same seeds should be identical.
- Specified by:
setSeed
in interfaceRandomGenerator
- Parameters:
seed
- the seed value
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nextInt
public int nextInt()Returns the next pseudorandom, uniformly distributedint
value from this random number generator's sequence.All 232 possible
int
values should be produced with (approximately) equal probability.- Specified by:
nextInt
in interfaceRandomGenerator
- Returns:
- the next pseudorandom, uniformly distributed
int
value from this random number generator's sequence
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nextBoolean
public boolean nextBoolean()Returns the next pseudorandom, uniformly distributedboolean
value from this random number generator's sequence.- Returns:
- the next pseudorandom, uniformly distributed
boolean
value from this random number generator's sequence
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nextDouble
public double nextDouble()Returns the next pseudorandom, uniformly distributeddouble
value between0.0
and1.0
from this random number generator's sequence.- Returns:
- the next pseudorandom, uniformly distributed
double
value between0.0
and1.0
from this random number generator's sequence
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nextFloat
public float nextFloat()Returns the next pseudorandom, uniformly distributedfloat
value between0.0
and1.0
from this random number generator's sequence.- Returns:
- the next pseudorandom, uniformly distributed
float
value between0.0
and1.0
from this random number generator's sequence
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nextLong
public long nextLong()Returns the next pseudorandom, uniformly distributedlong
value from this random number generator's sequence. All 264 possiblelong
values should be produced with (approximately) equal probability.- Returns:
- the next pseudorandom, uniformly distributed
long
value from this random number generator's sequence
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nextBytes
public void nextBytes(byte[] bytes) Generates random bytes and places them into a user-supplied byte array. The number of random bytes produced is equal to the length of the byte array.- Parameters:
bytes
- the non-null byte array in which to put the random bytes
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nextBytes
public void nextBytes(byte[] bytes, int start, int len) Generates random bytes and places them into a user-supplied byte array.- Parameters:
bytes
- the non-null byte array in which to put the random bytesstart
- the starting index for inserting the generated bytes into the arraylen
- the number of bytes to generate
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setSeed
public void setSeed(int seed) Sets the seed of the underlying random number generator using anint
seed.Sequences of values generated starting with the same seeds should be identical.
- Specified by:
setSeed
in interfaceRandomGenerator
- Parameters:
seed
- the seed value
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setSeed
public void setSeed(long seed) Sets the seed of the underlying random number generator using along
seed.Sequences of values generated starting with the same seeds should be identical.
- Specified by:
setSeed
in interfaceRandomGenerator
- Parameters:
seed
- the seed value
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nextInt
Returns a pseudorandom, uniformly distributedint
value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence.- Specified by:
nextInt
in interfaceRandomGenerator
- Parameters:
n
- the bound on the random number to be returned. Must be positive.- Returns:
- a pseudorandom, uniformly distributed
int
value between 0 (inclusive) and n (exclusive). - Throws:
IllegalArgumentException
- if n is not positive.
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nextLong
public long nextLong(long n) Returns a pseudorandom, uniformly distributedint
value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence.- Specified by:
nextLong
in interfaceRandomGenerator
- Parameters:
n
- the bound on the random number to be returned. Must be positive.- Returns:
- a pseudorandom, uniformly distributed
int
value between 0 (inclusive) and n (exclusive).
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nextGaussian
public double nextGaussian()Returns the next pseudorandom, Gaussian ("normally") distributeddouble
value with mean0.0
and standard deviation1.0
from this random number generator's sequence.- Specified by:
nextGaussian
in interfaceRandomGenerator
- Returns:
- the next pseudorandom, Gaussian ("normally") distributed
double
value with mean0.0
and standard deviation1.0
from this random number generator's sequence
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clearCache
protected void clearCache()Clears the cache used by the default implementation ofRandomGenerator.nextGaussian()
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toString
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