public class XoRoShiRo128PlusRandom extends Random
xorshift128+
under every respect: it is faster and has stronger statistical properties.
More details can be found on the xoroshiro+
/xorshift*
/xorshift+
generators and the PRNG shootout page.
Warning: the output of this generator might change in the near future.
Note that this is
not a cryptographicstrength pseudorandom number generator, but its quality is
preposterously higher than Random
's, and its cycle length is
2^{128} − 1, which is more than enough for any singlethread application.
By using the supplied jump()
method it is possible to generate nonoverlapping long sequences
for parallel computations. This class provides also a split()
method to support recursive parallel computations, in the spirit of
Java 8's SplittableRandom
.
it.unimi.dsi.util
,
RandomGenerator
,
Serialized FormConstructor and Description 

XoRoShiRo128PlusRandom()
Creates a new generator seeded using
Util.randomSeed() . 
XoRoShiRo128PlusRandom(long seed)
Creates a new generator using a given seed.

Modifier and Type  Method and Description 

void 
jump()
The the jump function for this generator.

static void 
main(String[] arg) 
boolean 
nextBoolean() 
void 
nextBytes(byte[] bytes) 
double 
nextDouble() 
double 
nextDoubleFast()
Returns the next pseudorandom, uniformly distributed
double value between 0.0 and
1.0 from this random number generator's sequence,
using a fast multiplicationfree method which, however,
can provide only 52 significant bits. 
float 
nextFloat() 
int 
nextInt() 
int 
nextInt(int n) 
long 
nextLong() 
long 
nextLong(long n)
Returns a pseudorandom uniformly distributed
long value
between 0 (inclusive) and the specified value (exclusive), drawn from
this random number generator's sequence. 
void 
setSeed(long seed)
Sets the seed of this generator.

void 
setState(long[] state)
Sets the state of this generator.

XoRoShiRo128PlusRandom 
split()
Returns a new instance that shares no mutable state
with this instance.

public XoRoShiRo128PlusRandom()
Util.randomSeed()
.public XoRoShiRo128PlusRandom(long seed)
seed
 a seed for the generator.public long nextLong(long n)
long
value
between 0 (inclusive) and the specified value (exclusive), drawn from
this random number generator's sequence. The algorithm used to generate
the value guarantees that the result is uniform, provided that the
sequence of 64bit values produced by this generator is.n
 the positive bound on the random number to be returned.long
value between 0
(inclusive) and n
(exclusive).public double nextDouble()
nextDouble
in class Random
public double nextDoubleFast()
double
value between 0.0
and
1.0
from this random number generator's sequence,
using a fast multiplicationfree method which, however,
can provide only 52 significant bits.
This method is faster than nextDouble()
, but it
can return only dyadic rationals of the form k / 2^{−52},
instead of the standard k / 2^{−53}. Before
version 2.4.1, this was actually the standard implementation of
nextDouble()
, so you can use this method if you need to
reproduce exactly results obtained using previous versions.
The only difference between the output of this method and that of
nextDouble()
is an additional least significant bit set in half of the
returned values. For most applications, this difference is negligible.
double
value between 0.0
and 1.0
from this
random number generator's sequence, using 52 significant bits only.public boolean nextBoolean()
nextBoolean
in class Random
public void jump()
nextLong()
; it can be used to generate 2^{64}
nonoverlapping subsequences for parallel computations.public XoRoShiRo128PlusRandom split()
public void setSeed(long seed)
The argument will be used to seed a SplitMix64RandomGenerator
, whose output
will in turn be used to seed this generator. This approach makes “warmup” unnecessary,
and makes the probability of starting from a state
with a large fraction of bits set to zero astronomically small.
public void setState(long[] state)
The internal state of the generator will be reset, and the state array filled with the provided array.
state
 an array of 2 longs; at least one must be nonzero.public static void main(String[] arg)