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java.util.concurrent

public final Class ThreadLocalRandom

extends Random
Class Inheritance
Imports
java.io.ObjectStreamField, java.util.Random, java.util.concurrent.atomic.AtomicInteger, .AtomicLong, java.util.stream.DoubleStream, .IntStream, .LongStream, jdk.internal.access.JavaLangAccess, .JavaUtilConcurrentTLRAccess, .SharedSecrets, jdk.internal.util.random.RandomSupport, jdk.internal.util.random.RandomSupport.*, jdk.internal.misc.Unsafe, .VM
A random number generator (with period 264) isolated to the current thread. Like the global java.util.Random generator used by the java.lang.Math class, a ThreadLocalRandom is initialized with an internally generated seed that may not otherwise be modified. When applicable, use of ThreadLocalRandom rather than shared Random objects in concurrent programs will typically encounter much less overhead and contention. Use of ThreadLocalRandom is particularly appropriate when multiple tasks (for example, each a ForkJoinTask) use random numbers in parallel in thread pools.

Usages of this class should typically be of the form: ThreadLocalRandom.current().nextX(...) (where X is Int, Long, etc). When all usages are of this form, it is never possible to accidentally share a ThreadLocalRandom across multiple threads.

This class also provides additional commonly used bounded random generation methods.

Instances of ThreadLocalRandom are not cryptographically secure. Consider instead using java.security.SecureRandom in security-sensitive applications. Additionally, default-constructed instances do not use a cryptographically random seed unless the system property java.util.secureRandomSeed is set to true.

Author
Doug Lea
Since
1.7

Nested and Inner Type Summary

Modifier and TypeClass and Description
private static class
ThreadLocalRandom.Access

private static class
ThreadLocalRandom.ThreadLocalRandomProxy

Field Summary

Modifier and TypeField and Description
private static final long
GOLDEN_GAMMA

The seed increment.

private static final long
INHERITABLETHREADLOCALS

pack-priv boolean
initialized

Field used only during singleton initialization.

private static final ThreadLocalRandom
instance

The common ThreadLocalRandom

private static final JavaLangAccess
JLA

private static final long
PROBE

private static final int
PROBE_INCREMENT

The increment for generating probe values.

private static final AtomicInteger
probeGenerator

Generates per-thread initialization/probe field

private static final long
SECONDARY

private static final long
SEED

private static final AtomicLong
seeder

The next seed for default constructors.

private static final long
SEEDER_INCREMENT

The increment of seeder per new instance.

private static final ObjectStreamField[]
serialPersistentFields

Hides java.util.Random.serialPersistentFields.

private static final long
serialVersionUID

Hides java.util.Random.serialVersionUID.

private static final long
THREADLOCALS

private static final Unsafe
U

Constructor Summary

AccessConstructor and Description
private
ThreadLocalRandom()

Constructor used only for static singleton

Method Summary

Modifier and TypeMethod and Description
pack-priv static final int
advanceProbe(int probe)

Pseudo-randomly advances and records the given probe value for the given thread.

public static ThreadLocalRandom

Returns:

the current thread's ThreadLocalRandom
current()

Returns the current thread's ThreadLocalRandom object.

public DoubleStream
doubles(long streamSize)

Overrides java.util.Random.doubles.

Overrides default java.util.random.RandomGenerator.doubles.

Returns a stream producing the given streamSize number of pseudorandom double values, each between zero (inclusive) and one (exclusive).

public DoubleStream
doubles()

Overrides java.util.Random.doubles.

Overrides default java.util.random.RandomGenerator.doubles.

Returns an effectively unlimited stream of pseudorandom double values, each between zero (inclusive) and one (exclusive).

public DoubleStream
doubles(long streamSize, double randomNumberOrigin, double randomNumberBound)

Overrides java.util.Random.doubles.

Overrides default java.util.random.RandomGenerator.doubles.

Returns a stream producing the given streamSize number of pseudorandom double values, each conforming to the given origin (inclusive) and bound (exclusive).

public DoubleStream
doubles(double randomNumberOrigin, double randomNumberBound)

Overrides java.util.Random.doubles.

Overrides default java.util.random.RandomGenerator.doubles.

Returns an effectively unlimited stream of pseudorandom double values, each conforming to the given origin (inclusive) and bound (exclusive).

pack-priv static final void
eraseThreadLocals(Thread thread)

Erases ThreadLocals by nulling out Thread maps.

pack-priv static final int
getProbe()

Returns the probe value for the current thread without forcing initialization.

public IntStream
ints(long streamSize)

Overrides java.util.Random.ints.

Overrides default java.util.random.RandomGenerator.ints.

Returns a stream producing the given streamSize number of pseudorandom int values.

public IntStream
ints()

Overrides java.util.Random.ints.

Overrides default java.util.random.RandomGenerator.ints.

Returns an effectively unlimited stream of pseudorandom int values.

public IntStream
ints(long streamSize, int randomNumberOrigin, int randomNumberBound)

Overrides java.util.Random.ints.

Overrides default java.util.random.RandomGenerator.ints.

Returns a stream producing the given streamSize number of pseudorandom int values, each conforming to the given origin (inclusive) and bound (exclusive).

public IntStream
ints(int randomNumberOrigin, int randomNumberBound)

Overrides java.util.Random.ints.

Overrides default java.util.random.RandomGenerator.ints.

Returns an effectively unlimited stream of pseudorandom int values, each conforming to the given origin (inclusive) and bound (exclusive).

pack-priv static final void
localInit()

Initialize Thread fields for the current thread.

public LongStream
longs(long streamSize)

Overrides java.util.Random.longs.

Overrides default java.util.random.RandomGenerator.longs.

Returns a stream producing the given streamSize number of pseudorandom long values.

public LongStream
longs()

Overrides java.util.Random.longs.

Overrides default java.util.random.RandomGenerator.longs.

Returns an effectively unlimited stream of pseudorandom long values.

public LongStream
longs(long streamSize, long randomNumberOrigin, long randomNumberBound)

Overrides java.util.Random.longs.

Overrides default java.util.random.RandomGenerator.longs.

Returns a stream producing the given streamSize number of pseudorandom long, each conforming to the given origin (inclusive) and bound (exclusive).

public LongStream
longs(long randomNumberOrigin, long randomNumberBound)

Overrides java.util.Random.longs.

Overrides default java.util.random.RandomGenerator.longs.

Returns an effectively unlimited stream of pseudorandom long values, each conforming to the given origin (inclusive) and bound (exclusive).

private static int
mix32(long z)

protected int

Returns:

the next pseudorandom value from this random number generator's sequence
next(int
random bits
bits)

Overrides java.util.Random.next.

Generates a pseudorandom number with the indicated number of low-order bits.

public boolean
nextBoolean()

Overrides java.util.Random.nextBoolean.

Overrides default java.util.random.RandomGenerator.nextBoolean.

Returns the next pseudorandom, uniformly distributed boolean value from this random number generator's sequence.

public double
nextDouble()

Overrides java.util.Random.nextDouble.

Overrides default java.util.random.RandomGenerator.nextDouble.

Returns the next pseudorandom, uniformly distributed double value between 0.0 and 1.0 from this random number generator's sequence.

public double
nextDouble(double bound)

Overrides default java.util.random.RandomGenerator.nextDouble.

Returns a pseudorandomly chosen double value between zero (inclusive) and the specified bound (exclusive).

public double
nextDouble(double origin, double bound)

Overrides default java.util.random.RandomGenerator.nextDouble.

Returns a pseudorandomly chosen double value between the specified origin (inclusive) and the specified bound (exclusive).

public float
nextFloat()

Overrides java.util.Random.nextFloat.

Overrides default java.util.random.RandomGenerator.nextFloat.

Returns the next pseudorandom, uniformly distributed float value between 0.0 and 1.0 from this random number generator's sequence.

public float
nextFloat(float bound)

Overrides default java.util.random.RandomGenerator.nextFloat.

Returns a pseudorandomly chosen float value between zero (inclusive) and the specified bound (exclusive).

public float
nextFloat(float origin, float bound)

Overrides default java.util.random.RandomGenerator.nextFloat.

Returns a pseudorandomly chosen float value between the specified origin (inclusive) and the specified bound (exclusive).

public double

Returns:

a double value pseudorandomly chosen from a Gaussian distribution
nextGaussian()

Overrides java.util.Random.nextGaussian.

Overrides default java.util.random.RandomGenerator.nextGaussian.

Returns a double value pseudorandomly chosen from a Gaussian (normal) distribution whose mean is 0 and whose standard deviation is 1.

public int
nextInt()

Overrides java.util.Random.nextInt.

Overrides default java.util.random.RandomGenerator.nextInt.

Returns the next pseudorandom, uniformly distributed int value from this random number generator's sequence.

public int
nextInt(int bound)

Overrides java.util.Random.nextInt.

Overrides default java.util.random.RandomGenerator.nextInt.

Returns a pseudorandom, uniformly distributed int value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence.

public int
nextInt(int origin, int bound)

Overrides default java.util.random.RandomGenerator.nextInt.

Returns a pseudorandomly chosen int value between the specified origin (inclusive) and the specified bound (exclusive).

public long
nextLong()

Overrides java.util.Random.nextLong.

Implements java.util.random.RandomGenerator.nextLong.

Returns the next pseudorandom, uniformly distributed long value from this random number generator's sequence.

public long
nextLong(long bound)

Overrides default java.util.random.RandomGenerator.nextLong.

Returns a pseudorandomly chosen long value between zero (inclusive) and the specified bound (exclusive).

public long
nextLong(long origin, long bound)

Overrides default java.util.random.RandomGenerator.nextLong.

Returns a pseudorandomly chosen long value between the specified origin (inclusive) and the specified bound (exclusive).

pack-priv static final int
nextSecondarySeed()

Returns the pseudo-randomly initialized or updated secondary seed.

pack-priv final long
nextSeed()

Update the thread local seed value by adding to it the sum of GOLDEN_GAMMA (an odd value) and twice the thread id. This sum is always odd (to guarantee that the generator has maximum period) and is different for different threads.

private Object

Returns:

the current thread's ThreadLocalRandom
readResolve()

Returns the current thread's ThreadLocalRandom.

public void
setSeed(long seed)

Overrides java.util.Random.setSeed.

Throws UnsupportedOperationException.

private void
writeObject(ObjectOutputStream
the stream
s)

Hides java.util.Random.writeObject.

Saves the ThreadLocalRandom to a stream (that is, serializes it).

Inherited from java.util.Random:
fromnextBytes

Field Detail

GOLDEN_GAMMAback to summary
private static final long GOLDEN_GAMMA

The seed increment. This must be an odd value for the generator to have the maximum period (2 to the 64th power). The value 0x9e3779b97f4a7c15L is odd, and moreover consists of the first 64 bits of the fractional part of the golden ratio, which is known to generate good Weyl sequences.

INHERITABLETHREADLOCALSback to summary
private static final long INHERITABLETHREADLOCALS
initializedback to summary
pack-priv boolean initialized

Field used only during singleton initialization. True when constructor completes.

instanceback to summary
private static final ThreadLocalRandom instance

The common ThreadLocalRandom

JLAback to summary
private static final JavaLangAccess JLA
PROBEback to summary
private static final long PROBE
PROBE_INCREMENTback to summary
private static final int PROBE_INCREMENT

The increment for generating probe values.

probeGeneratorback to summary
private static final AtomicInteger probeGenerator

Generates per-thread initialization/probe field

SECONDARYback to summary
private static final long SECONDARY
SEEDback to summary
private static final long SEED
seederback to summary
private static final AtomicLong seeder

The next seed for default constructors.

SEEDER_INCREMENTback to summary
private static final long SEEDER_INCREMENT

The increment of seeder per new instance.

serialPersistentFieldsback to summary
private static final ObjectStreamField[] serialPersistentFields

Hides java.util.Random.serialPersistentFields.

Serial Fields:
rnd:long
seed for random computations
initialized:boolean
always true
serialVersionUIDback to summary
private static final long serialVersionUID

Hides java.util.Random.serialVersionUID.

THREADLOCALSback to summary
private static final long THREADLOCALS
Uback to summary
private static final Unsafe U

Constructor Detail

ThreadLocalRandomback to summary
private ThreadLocalRandom()

Constructor used only for static singleton

Method Detail

advanceProbeback to summary
pack-priv static final int advanceProbe(int probe)

Pseudo-randomly advances and records the given probe value for the given thread.

currentback to summary
public static ThreadLocalRandom current()

Returns the current thread's ThreadLocalRandom object. Methods of this object should be called only by the current thread, not by other threads.

Returns:ThreadLocalRandom

the current thread's ThreadLocalRandom

doublesback to summary
public DoubleStream doubles(long streamSize)

Overrides java.util.Random.doubles.

Overrides default java.util.random.RandomGenerator.doubles.

Doc from java.util.Random.doubles.

Returns a stream producing the given streamSize number of pseudorandom double values, each between zero (inclusive) and one (exclusive).

A pseudorandom double value is generated as if it's the result of calling the method nextDouble().

Annotations
@Override
Exceptions
IllegalArgumentException:
if streamSize is less than zero
Since
1.8
doublesback to summary
public DoubleStream doubles()

Overrides java.util.Random.doubles.

Overrides default java.util.random.RandomGenerator.doubles.

Doc from java.util.Random.doubles.

Returns an effectively unlimited stream of pseudorandom double values, each between zero (inclusive) and one (exclusive).

A pseudorandom double value is generated as if it's the result of calling the method nextDouble().

Implementation Note

This method is implemented to be equivalent to doubles(Long.MAX_VALUE).

Annotations
@Override
Since
1.8
doublesback to summary
public DoubleStream doubles(long streamSize, double randomNumberOrigin, double randomNumberBound)

Overrides java.util.Random.doubles.

Overrides default java.util.random.RandomGenerator.doubles.

Doc from java.util.Random.doubles.

Returns a stream producing the given streamSize number of pseudorandom double values, each conforming to the given origin (inclusive) and bound (exclusive).

Annotations
@Override
Exceptions
IllegalArgumentException:
if streamSize is less than zero, or randomNumberOrigin is not finite, or randomNumberBound is not finite, or randomNumberOrigin is greater than or equal to randomNumberBound
Since
1.8
doublesback to summary
public DoubleStream doubles(double randomNumberOrigin, double randomNumberBound)

Overrides java.util.Random.doubles.

Overrides default java.util.random.RandomGenerator.doubles.

Doc from java.util.Random.doubles.

Returns an effectively unlimited stream of pseudorandom double values, each conforming to the given origin (inclusive) and bound (exclusive).

Implementation Note

This method is implemented to be equivalent to doubles(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound).

Annotations
@Override
Exceptions
IllegalArgumentException:
if randomNumberOrigin is not finite, or randomNumberBound is not finite, or randomNumberOrigin is greater than or equal to randomNumberBound
Since
1.8
eraseThreadLocalsback to summary
pack-priv static final void eraseThreadLocals(Thread thread)

Erases ThreadLocals by nulling out Thread maps.

getProbeback to summary
pack-priv static final int getProbe()

Returns the probe value for the current thread without forcing initialization. Note that invoking ThreadLocalRandom.current() can be used to force initialization on zero return.

intsback to summary
public IntStream ints(long streamSize)

Overrides java.util.Random.ints.

Overrides default java.util.random.RandomGenerator.ints.

Doc from java.util.Random.ints.

Returns a stream producing the given streamSize number of pseudorandom int values.

A pseudorandom int value is generated as if it's the result of calling the method nextInt().

Annotations
@Override
Exceptions
IllegalArgumentException:
if streamSize is less than zero
Since
1.8
intsback to summary
public IntStream ints()

Overrides java.util.Random.ints.

Overrides default java.util.random.RandomGenerator.ints.

Doc from java.util.Random.ints.

Returns an effectively unlimited stream of pseudorandom int values.

A pseudorandom int value is generated as if it's the result of calling the method nextInt().

Implementation Note

This method is implemented to be equivalent to ints(Long.MAX_VALUE).

Annotations
@Override
Since
1.8
intsback to summary
public IntStream ints(long streamSize, int randomNumberOrigin, int randomNumberBound)

Overrides java.util.Random.ints.

Overrides default java.util.random.RandomGenerator.ints.

Doc from java.util.Random.ints.

Returns a stream producing the given streamSize number of pseudorandom int values, each conforming to the given origin (inclusive) and bound (exclusive).

A pseudorandom int value is generated as if it's the result of calling the following method with the origin and bound: 

 int nextInt(int origin, int bound) {
  int n = bound - origin;
  if (n > 0) {
    return nextInt(n) + origin;
  }
  else {  // range not representable as int
    int r;
    do {
      r = nextInt();
    } while (r < origin || r >= bound);
    return r;
  }
}
Annotations
@Override
Exceptions
IllegalArgumentException:
if streamSize is less than zero, or randomNumberOrigin is greater than or equal to randomNumberBound
Since
1.8
intsback to summary
public IntStream ints(int randomNumberOrigin, int randomNumberBound)

Overrides java.util.Random.ints.

Overrides default java.util.random.RandomGenerator.ints.

Doc from java.util.Random.ints.

Returns an effectively unlimited stream of pseudorandom int values, each conforming to the given origin (inclusive) and bound (exclusive).

A pseudorandom int value is generated as if it's the result of calling the following method with the origin and bound: 

 int nextInt(int origin, int bound) {
  int n = bound - origin;
  if (n > 0) {
    return nextInt(n) + origin;
  }
  else {  // range not representable as int
    int r;
    do {
      r = nextInt();
    } while (r < origin || r >= bound);
    return r;
  }
}

Implementation Note

This method is implemented to be equivalent to ints(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound).

Annotations
@Override
Exceptions
IllegalArgumentException:
if randomNumberOrigin is greater than or equal to randomNumberBound
Since
1.8
localInitback to summary
pack-priv static final void localInit()

Initialize Thread fields for the current thread. Called only when Thread.threadLocalRandomProbe is zero, indicating that a thread local seed value needs to be generated. Note that even though the initialization is purely thread-local, we need to rely on (static) atomic generators to initialize the values.

longsback to summary
public LongStream longs(long streamSize)

Overrides java.util.Random.longs.

Overrides default java.util.random.RandomGenerator.longs.

Doc from java.util.Random.longs.

Returns a stream producing the given streamSize number of pseudorandom long values.

A pseudorandom long value is generated as if it's the result of calling the method nextLong().

Annotations
@Override
Exceptions
IllegalArgumentException:
if streamSize is less than zero
Since
1.8
longsback to summary
public LongStream longs()

Overrides java.util.Random.longs.

Overrides default java.util.random.RandomGenerator.longs.

Doc from java.util.Random.longs.

Returns an effectively unlimited stream of pseudorandom long values.

A pseudorandom long value is generated as if it's the result of calling the method nextLong().

Implementation Note

This method is implemented to be equivalent to longs(Long.MAX_VALUE).

Annotations
@Override
Since
1.8
longsback to summary
public LongStream longs(long streamSize, long randomNumberOrigin, long randomNumberBound)

Overrides java.util.Random.longs.

Overrides default java.util.random.RandomGenerator.longs.

Doc from java.util.Random.longs.

Returns a stream producing the given streamSize number of pseudorandom long, each conforming to the given origin (inclusive) and bound (exclusive).

A pseudorandom long value is generated as if it's the result of calling the following method with the origin and bound: 

 long nextLong(long origin, long bound) {
  long r = nextLong();
  long n = bound - origin, m = n - 1;
  if ((n & m) == 0L)  // power of two
    r = (r & m) + origin;
  else if (n > 0L) {  // reject over-represented candidates
    for (long u = r >>> 1;            // ensure nonnegative
         u + m - (r = u % n) < 0L;    // rejection check
         u = nextLong() >>> 1) // retry
        ;
    r += origin;
  }
  else {              // range not representable as long
    while (r < origin || r >= bound)
      r = nextLong();
  }
  return r;
}
Annotations
@Override
Exceptions
IllegalArgumentException:
if streamSize is less than zero, or randomNumberOrigin is greater than or equal to randomNumberBound
Since
1.8
longsback to summary
public LongStream longs(long randomNumberOrigin, long randomNumberBound)

Overrides java.util.Random.longs.

Overrides default java.util.random.RandomGenerator.longs.

Doc from java.util.Random.longs.

Returns an effectively unlimited stream of pseudorandom long values, each conforming to the given origin (inclusive) and bound (exclusive).

A pseudorandom long value is generated as if it's the result of calling the following method with the origin and bound: 

 long nextLong(long origin, long bound) {
  long r = nextLong();
  long n = bound - origin, m = n - 1;
  if ((n & m) == 0L)  // power of two
    r = (r & m) + origin;
  else if (n > 0L) {  // reject over-represented candidates
    for (long u = r >>> 1;            // ensure nonnegative
         u + m - (r = u % n) < 0L;    // rejection check
         u = nextLong() >>> 1) // retry
        ;
    r += origin;
  }
  else {              // range not representable as long
    while (r < origin || r >= bound)
      r = nextLong();
  }
  return r;
}

Implementation Note

This method is implemented to be equivalent to longs(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound).

Annotations
@Override
Exceptions
IllegalArgumentException:
if randomNumberOrigin is greater than or equal to randomNumberBound
Since
1.8
mix32back to summary
private static int mix32(long z)
nextback to summary
protected int next(int bits)

Overrides java.util.Random.next.

Generates a pseudorandom number with the indicated number of low-order bits. Because this class has no subclasses, this method cannot be invoked or overridden.

Parameters
bits:int

random bits

Returns:int

the next pseudorandom value from this random number generator's sequence

nextBooleanback to summary
public boolean nextBoolean()

Overrides java.util.Random.nextBoolean.

Overrides default java.util.random.RandomGenerator.nextBoolean.

Doc from java.util.Random.nextBoolean.

Returns the next pseudorandom, uniformly distributed boolean value from this random number generator's sequence. The general contract of nextBoolean is that one boolean value is pseudorandomly generated and returned. The values true and false are produced with (approximately) equal probability.

Annotations
@Override
nextDoubleback to summary
public double nextDouble()

Overrides java.util.Random.nextDouble.

Overrides default java.util.random.RandomGenerator.nextDouble.

Doc from java.util.Random.nextDouble.

Returns the next pseudorandom, uniformly distributed double value between 0.0 and 1.0 from this random number generator's sequence.

The general contract of nextDouble is that one double value, chosen (approximately) uniformly from the range 0.0d (inclusive) to 1.0d (exclusive), is pseudorandomly generated and returned.

Annotations
@Override
nextDoubleback to summary
public double nextDouble(double bound)

Overrides default java.util.random.RandomGenerator.nextDouble.

Doc from java.util.random.RandomGenerator.nextDouble.

Returns a pseudorandomly chosen double value between zero (inclusive) and the specified bound (exclusive).

Annotations
@Override
Exceptions
IllegalArgumentException:
if bound is not both positive and finite
nextDoubleback to summary
public double nextDouble(double origin, double bound)

Overrides default java.util.random.RandomGenerator.nextDouble.

Doc from java.util.random.RandomGenerator.nextDouble.

Returns a pseudorandomly chosen double value between the specified origin (inclusive) and the specified bound (exclusive).

Annotations
@Override
Exceptions
IllegalArgumentException:
if origin is not finite, or bound is not finite, or origin is greater than or equal to bound
nextFloatback to summary
public float nextFloat()

Overrides java.util.Random.nextFloat.

Overrides default java.util.random.RandomGenerator.nextFloat.

Doc from java.util.Random.nextFloat.

Returns the next pseudorandom, uniformly distributed float value between 0.0 and 1.0 from this random number generator's sequence.

The general contract of nextFloat is that one float value, chosen (approximately) uniformly from the range 0.0f (inclusive) to 1.0f (exclusive), is pseudorandomly generated and returned. All 224 possible float values of the form m x 2-24, where m is a positive integer less than 224, are produced with (approximately) equal probability.

Annotations
@Override
nextFloatback to summary
public float nextFloat(float bound)

Overrides default java.util.random.RandomGenerator.nextFloat.

Doc from java.util.random.RandomGenerator.nextFloat.

Returns a pseudorandomly chosen float value between zero (inclusive) and the specified bound (exclusive).

Annotations
@Override
Exceptions
IllegalArgumentException:
if bound is not both positive and finite
Since
17
nextFloatback to summary
public float nextFloat(float origin, float bound)

Overrides default java.util.random.RandomGenerator.nextFloat.

Doc from java.util.random.RandomGenerator.nextFloat.

Returns a pseudorandomly chosen float value between the specified origin (inclusive) and the specified bound (exclusive).

Annotations
@Override
Exceptions
IllegalArgumentException:
if origin is not finite, or bound is not finite, or origin is greater than or equal to bound
Since
17
nextGaussianback to summary
public double nextGaussian()

Overrides java.util.Random.nextGaussian.

Overrides default java.util.random.RandomGenerator.nextGaussian.

Returns a double value pseudorandomly chosen from a Gaussian (normal) distribution whose mean is 0 and whose standard deviation is 1.

Implementation Note

This implementation invokes the default implementation of java.util.random.RandomGenerator#nextGaussian(), and so it uses McFarland's fast modified ziggurat algorithm rather than the polar method described in the superclass.

Returns:double

a double value pseudorandomly chosen from a Gaussian distribution

Annotations
@Override
nextIntback to summary
public int nextInt()

Overrides java.util.Random.nextInt.

Overrides default java.util.random.RandomGenerator.nextInt.

Doc from java.util.Random.nextInt.

Returns the next pseudorandom, uniformly distributed int value from this random number generator's sequence. The general contract of nextInt is that one int value is pseudorandomly generated and returned. All 232 possible int values are produced with (approximately) equal probability.

Annotations
@Override
nextIntback to summary
public int nextInt(int bound)

Overrides java.util.Random.nextInt.

Overrides default java.util.random.RandomGenerator.nextInt.

Doc from java.util.Random.nextInt.

Returns a pseudorandom, uniformly distributed int value between 0 (inclusive) and the specified value (exclusive), drawn from this random number generator's sequence. The general contract of nextInt is that one int value in the specified range is pseudorandomly generated and returned. All bound possible int values are produced with (approximately) equal probability.

Annotations
@Override
Exceptions
IllegalArgumentException:
if bound is not positive
nextIntback to summary
public int nextInt(int origin, int bound)

Overrides default java.util.random.RandomGenerator.nextInt.

Doc from java.util.random.RandomGenerator.nextInt.

Returns a pseudorandomly chosen int value between the specified origin (inclusive) and the specified bound (exclusive).

Annotations
@Override
Exceptions
IllegalArgumentException:
if origin is greater than or equal to bound
nextLongback to summary
public long nextLong()

Overrides java.util.Random.nextLong.

Implements java.util.random.RandomGenerator.nextLong.

Doc from java.util.Random.nextLong.

Returns the next pseudorandom, uniformly distributed long value from this random number generator's sequence. The general contract of nextLong is that one long value is pseudorandomly generated and returned.

Annotations
@Override
nextLongback to summary
public long nextLong(long bound)

Overrides default java.util.random.RandomGenerator.nextLong.

Doc from java.util.random.RandomGenerator.nextLong.

Returns a pseudorandomly chosen long value between zero (inclusive) and the specified bound (exclusive).

Annotations
@Override
Exceptions
IllegalArgumentException:
if bound is not positive
nextLongback to summary
public long nextLong(long origin, long bound)

Overrides default java.util.random.RandomGenerator.nextLong.

Doc from java.util.random.RandomGenerator.nextLong.

Returns a pseudorandomly chosen long value between the specified origin (inclusive) and the specified bound (exclusive).

Annotations
@Override
Exceptions
IllegalArgumentException:
if origin is greater than or equal to bound
nextSecondarySeedback to summary
pack-priv static final int nextSecondarySeed()

Returns the pseudo-randomly initialized or updated secondary seed.

nextSeedback to summary
pack-priv final long nextSeed()

Update the thread local seed value by adding to it the sum of GOLDEN_GAMMA (an odd value) and twice the thread id. This sum is always odd (to guarantee that the generator has maximum period) and is different for different threads. Because thread id values are allocated consecutively starting from 0, the high 32 bits of this sum will be the same as the high 32 bits of GOLDEN_GAMMA unless an extremely large number of threads have been created, and so the overall value added to the thread local seed value will have at least fourteen 01 and 10 transitions (see the documentation for the method mixGamma in class SplittableRandom), which should provide adequate statistical quality for applications likely to use ThreadLocalRandom.

readResolveback to summary
private Object readResolve()

Returns the current thread's ThreadLocalRandom.

Returns:Object

the current thread's ThreadLocalRandom

setSeedback to summary
public void setSeed(long seed)

Overrides java.util.Random.setSeed.

Throws UnsupportedOperationException. Setting seeds in this generator is not supported.

Exceptions
UnsupportedOperationException:
always
writeObjectback to summary
private void writeObject(ObjectOutputStream s) throws IOException

Hides java.util.Random.writeObject.

Saves the ThreadLocalRandom to a stream (that is, serializes it).

Parameters
s:ObjectOutputStream

the stream

Exceptions
IOException:
if an I/O error occurs
java.util.concurrent back to summary

private Class ThreadLocalRandom.Access

extends Object
Class Inheritance

Constructor Summary

AccessConstructor and Description
private
Access()

Method Summary

Inherited from java.lang.Object:
cloneequalsfinalizegetClasshashCodenotifynotifyAlltoStringwaitwaitwait

Constructor Detail

Accessback to summary
private Access()
java.util.concurrent back to summary

private final Class ThreadLocalRandom.ThreadLocalRandomProxy

extends Random
Class Inheritance
Annotations
@SuppressWarnings:serial

Field Summary

Modifier and TypeField and Description
pack-priv static final Random
PROXY

Constructor Summary

AccessConstructor and Description
private
ThreadLocalRandomProxy()

Method Summary

Modifier and TypeMethod and Description
public double
nextDouble()

Overrides java.util.Random.nextDouble.

Overrides default java.util.random.RandomGenerator.nextDouble.

Returns the next pseudorandom, uniformly distributed double value between 0.0 and 1.0 from this random number generator's sequence.

public int
nextInt()

Overrides java.util.Random.nextInt.

Overrides default java.util.random.RandomGenerator.nextInt.

Returns the next pseudorandom, uniformly distributed int value from this random number generator's sequence.

public long
nextLong()

Overrides java.util.Random.nextLong.

Implements java.util.random.RandomGenerator.nextLong.

Returns the next pseudorandom, uniformly distributed long value from this random number generator's sequence.

Inherited from java.util.Random:
doublesdoublesdoublesdoublesfromintsintsintsintslongslongslongslongsnextnextBooleannextBytesnextFloatnextGaussiannextIntsetSeed

Field Detail

PROXYback to summary
pack-priv static final Random PROXY

Constructor Detail

ThreadLocalRandomProxyback to summary
private ThreadLocalRandomProxy()

Method Detail

nextDoubleback to summary
public double nextDouble()

Overrides java.util.Random.nextDouble.

Overrides default java.util.random.RandomGenerator.nextDouble.

Doc from java.util.Random.nextDouble.

Returns the next pseudorandom, uniformly distributed double value between 0.0 and 1.0 from this random number generator's sequence.

The general contract of nextDouble is that one double value, chosen (approximately) uniformly from the range 0.0d (inclusive) to 1.0d (exclusive), is pseudorandomly generated and returned.

nextIntback to summary
public int nextInt()

Overrides java.util.Random.nextInt.

Overrides default java.util.random.RandomGenerator.nextInt.

Doc from java.util.Random.nextInt.

Returns the next pseudorandom, uniformly distributed int value from this random number generator's sequence. The general contract of nextInt is that one int value is pseudorandomly generated and returned. All 232 possible int values are produced with (approximately) equal probability.

nextLongback to summary
public long nextLong()

Overrides java.util.Random.nextLong.

Implements java.util.random.RandomGenerator.nextLong.

Doc from java.util.Random.nextLong.

Returns the next pseudorandom, uniformly distributed long value from this random number generator's sequence. The general contract of nextLong is that one long value is pseudorandomly generated and returned.