- All Superinterfaces:
RandomGenerator
,RandomGenerator.StreamableGenerator
- All Known Subinterfaces:
RandomGenerator.ArbitrarilyJumpableGenerator
,RandomGenerator.LeapableGenerator
- Enclosing interface:
- RandomGenerator
Ideally, all RandomGenerator.JumpableGenerator
objects produced by iterative
jumping from a single original RandomGenerator.JumpableGenerator
object are
statistically independent of one another and individually uniform. 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 either 264 or the square root of its
period. Implementors are advised to use algorithms whose period is at
least 2127.
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 RandomGenerator.JumpableGenerator
object, calls its jump
() method exactly
once, and then parcel out generators from the resulting stream, one to
each thread. It is generally not a good idea to call
jump
() on a generator that was itself
produced by the jump
() method, because the
result may be a generator identical to another generator already produce
by that call to the jump
() method. For
this reason, the return type of the jumps
()
method is Stream<RandomGenerator>
rather than
Stream<RandomGenerator.JumpableGenerator>
, even though the actual generator
objects in that stream likely do also implement the
RandomGenerator.JumpableGenerator
interface.
Objects that implement RandomGenerator.JumpableGenerator
are typically not
cryptographically secure. Consider instead using SecureRandom
to
get a cryptographically secure pseudo-random number generator for use by
security-sensitive applications.
-
Nested Class Summary
Nested classes/interfaces declared in interface java.util.random.RandomGenerator
RandomGenerator.ArbitrarilyJumpableGenerator, RandomGenerator.JumpableGenerator, RandomGenerator.LeapableGenerator, RandomGenerator.SplittableGenerator, RandomGenerator.StreamableGenerator
-
Method Summary
Modifier and TypeMethodDescriptioncopy()
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
Copy this generator, jump this generator forward, then return the copy.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.double
Returns the distance by which thejump
() method will jump forward within the state cycle of this generator object.default Stream<RandomGenerator>
jumps()
Returns an effectively unlimited stream of new pseudorandom number generators, each of which implements theRandomGenerator
interface.default Stream<RandomGenerator>
jumps
(long streamSize) Returns a stream producing the givenstreamSize
number of new pseudorandom number generators, each of which implements theRandomGenerator
interface.default Stream<RandomGenerator>
rngs()
Returns an effectively unlimited stream of new pseudorandom number generators, each of which implements theRandomGenerator
interface.default Stream<RandomGenerator>
rngs
(long streamSize) Returns a stream producing the givenstreamSize
number of new pseudorandom number generators, each of which implements theRandomGenerator
interface.Methods declared in interface java.util.random.RandomGenerator
doubles, doubles, doubles, doubles, ints, ints, ints, ints, isDeprecated, longs, longs, longs, longs, nextBoolean, nextBytes, nextDouble, nextDouble, nextDouble, nextExponential, nextFloat, nextFloat, nextFloat, nextGaussian, nextGaussian, nextInt, nextInt, nextInt, nextLong, nextLong, nextLong
-
Method Details
-
of
- Parameters:
name
- Name of random number generator algorithm- Returns:
- An instance of
RandomGenerator.JumpableGenerator
- Throws:
NullPointerException
- if name is nullIllegalArgumentException
- if the named algorithm is not found
-
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:
- a new object that is a copy of this generator
-
jump
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. -
jumpDistance
double jumpDistance()Returns the distance by which thejump
() method will jump forward within the state cycle of this generator object.- Returns:
- the default jump distance (as a
double
value)
-
jumps
Returns an effectively unlimited stream of new pseudorandom number generators, each of which implements theRandomGenerator
interface.- Implementation Requirements:
- The default implementation produces a sequential stream that repeatedly
calls
copy
() andjump
() on this generator, and the copies become the generators produced by the stream. - Implementation Note:
- It is permitted to implement this method in a manner equivalent to
jumps
(Long.MAX_VALUE
). - Returns:
- a stream of objects that implement the
RandomGenerator
interface
-
jumps
Returns a stream producing the givenstreamSize
number of new pseudorandom number generators, each of which implements theRandomGenerator
interface.- Implementation Requirements:
- The default implementation produces a sequential stream that repeatedly
calls
copy
() andjump
() on this generator, and the copies become the generators produced by the stream. - Parameters:
streamSize
- the number of generators to generate- Returns:
- a stream of objects that implement the
RandomGenerator
interface - Throws:
IllegalArgumentException
- ifstreamSize
is less than zero
-
rngs
Returns an effectively unlimited stream of new pseudorandom number generators, each of which implements theRandomGenerator
interface. Ideally the generators in the stream will appear to be statistically independent.- Specified by:
rngs
in interfaceRandomGenerator.StreamableGenerator
- Implementation Requirements:
- The default implementation calls
jump
(). - Returns:
- a stream of objects that implement the
RandomGenerator
interface
-
rngs
Returns a stream producing the givenstreamSize
number of new pseudorandom number generators, each of which implements theRandomGenerator
interface. Ideally the generators in the stream will appear to be statistically independent.- Specified by:
rngs
in interfaceRandomGenerator.StreamableGenerator
- Implementation Requirements:
- The default implementation calls
jumps
(streamSize). - Parameters:
streamSize
- the number of generators to generate- Returns:
- a stream of objects that implement the
RandomGenerator
interface - Throws:
IllegalArgumentException
- ifstreamSize
is less than zero
-
copyAndJump
Copy this generator, jump this generator forward, then return the copy.- Implementation Requirements:
- The default implementation copies this, jumps and then returns the copy.
- Returns:
- a copy of this generator object before the jump occurred
-