public class ThreadLocalRandom extends Random
Random
generator used by
the 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 accidently share a
ThreadLocalRandom
across multiple threads.
This class also provides additional commonly used bounded random generation methods.
限定符和类型 | 方法和说明 |
---|---|
static ThreadLocalRandom |
current()
Returns the current thread's
ThreadLocalRandom . |
double |
nextDouble(double n)
Returns a pseudorandom, uniformly distributed
double value between 0 (inclusive) and the specified value
(exclusive). |
double |
nextDouble(double least,
double bound)
Returns a pseudorandom, uniformly distributed value between the given least value (inclusive) and bound
(exclusive).
|
int |
nextInt(int least,
int bound)
Returns a pseudorandom, uniformly distributed value between the given least value (inclusive) and bound
(exclusive).
|
long |
nextLong(long n)
Returns a pseudorandom, uniformly distributed value between 0 (inclusive) and the specified value (exclusive).
|
long |
nextLong(long least,
long bound)
Returns a pseudorandom, uniformly distributed value between the given least value (inclusive) and bound
(exclusive).
|
void |
setSeed(long seed)
Throws
UnsupportedOperationException . |
nextBoolean, nextBytes, nextDouble, nextFloat, nextGaussian, nextInt, nextInt, nextLong
public static ThreadLocalRandom current()
ThreadLocalRandom
.ThreadLocalRandom
public void setSeed(long seed)
UnsupportedOperationException
. Setting seeds in this generator is not supported.setSeed
在类中 Random
UnsupportedOperationException
- alwayspublic int nextInt(int least, int bound)
least
- the least value returnedbound
- the upper bound (exclusive)IllegalArgumentException
- if least greater than or equal to boundpublic long nextLong(long n)
n
- the bound on the random number to be returned. Must be positive.IllegalArgumentException
- if n is not positivepublic long nextLong(long least, long bound)
least
- the least value returnedbound
- the upper bound (exclusive)IllegalArgumentException
- if least greater than or equal to boundpublic double nextDouble(double n)
double
value between 0 (inclusive) and the specified value
(exclusive).n
- the bound on the random number to be returned. Must be positive.IllegalArgumentException
- if n is not positivepublic double nextDouble(double least, double bound)
least
- the least value returnedbound
- the upper bound (exclusive)IllegalArgumentException
- if least greater than or equal to boundCopyright © 2012-2013 Alibaba Group. All Rights Reserved.