ThreadLocalRandom

java.lang.Object
- java.util.Random
- - jsr166y.ThreadLocalRandom

所有已实现的接口:

java.io.Serializable
```
public class ThreadLocalRandom
extends java.util.Random
```
A random number generator isolated to the current thread. Like the global 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.

从以下版本开始:

1.7

作者:

Doug Lea

另请参阅:
序列化表格

字段概要

字段
限定符和类型	字段和说明
`private static long`	`addend`
`(专用程序包) boolean`	`initialized` Initialization flag to permit the first and only allowed call to setSeed (inside Random constructor) to succeed.
`private static java.lang.ThreadLocal<ThreadLocalRandom>`	`localRandom` The actual ThreadLocal
`private static long`	`mask`
`private static long`	`multiplier`
`private long`	`pad0`
`private long`	`pad1`
`private long`	`pad2`
`private long`	`pad3`
`private long`	`pad4`
`private long`	`pad5`
`private long`	`pad6`
`private long`	`pad7`
`private long`	`rnd` The random seed.
`private static long`	`serialVersionUID`

构造器概要

构造器
构造器和说明

ThreadLocalRandom()
Constructor called only by localRandom.initialValue.

构造器
构造器和说明
`ThreadLocalRandom()` Constructor called only by localRandom.initialValue.

方法概要

方法
限定符和类型	方法和说明
`static ThreadLocalRandom`	`current()` Returns the current thread's `ThreadLocalRandom`.
`protected int`	`next(int bits)`
`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`.

从类继承的方法 java.util.Random
nextBoolean, nextBytes, nextDouble, nextFloat, nextGaussian, nextInt, nextInt, nextLong

从类继承的方法 java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- 字段详细资料
  - multiplier
```
private static final long multiplier
```
    另请参阅:
    常量字段值
  - addend
```
private static final long addend
```
    另请参阅:
    常量字段值
  - mask
```
private static final long mask
```
    另请参阅:
    常量字段值
  - rnd
```
private long rnd
```
    The random seed. We can't use super.seed.
  - initialized
```
boolean initialized
```
    Initialization flag to permit the first and only allowed call to setSeed (inside Random constructor) to succeed. We can't allow others since it would cause setting seed in one part of a program to unintentionally impact other usages by the thread.
  - pad0
```
private long pad0
```
  - pad1
```
private long pad1
```
  - pad2
```
private long pad2
```
  - pad3
```
private long pad3
```
  - pad4
```
private long pad4
```
  - pad5
```
private long pad5
```
  - pad6
```
private long pad6
```
  - pad7
```
private long pad7
```
  - localRandom
```
private static final java.lang.ThreadLocal<ThreadLocalRandom> localRandom
```
    The actual ThreadLocal
  - serialVersionUID
```
private static final long serialVersionUID
```
    另请参阅:
    常量字段值
- 构造器详细资料
  - ThreadLocalRandom
```
ThreadLocalRandom()
```
    Constructor called only by localRandom.initialValue. We rely on the fact that the superclass no-arg constructor invokes setSeed exactly once to initialize.
- 方法详细资料
  - current
```
public static ThreadLocalRandom current()
```
    Returns the current thread's ThreadLocalRandom.
    
    返回:
    the current thread's ThreadLocalRandom
  - setSeed
```
public void setSeed(long seed)
```
    Throws UnsupportedOperationException. Setting seeds in this generator is not supported.
    
    覆盖:
    
    setSeed 在类中 java.util.Random
    
    抛出:
    
    java.lang.UnsupportedOperationException - always
  - next
```
protected int next(int bits)
```
    覆盖:
    
    next 在类中 java.util.Random
  - nextInt
```
public int nextInt(int least,
          int bound)
```
    Returns a pseudorandom, uniformly distributed value between the given least value (inclusive) and bound (exclusive).
    
    参数:
    least - the least value returned
    bound - the upper bound (exclusive)
    
    返回:
    the next value
    
    抛出:
    
    java.lang.IllegalArgumentException - if least greater than or equal to bound
  - nextLong
```
public long nextLong(long n)
```
    Returns a pseudorandom, uniformly distributed value between 0 (inclusive) and the specified value (exclusive).
    
    参数:
    n - the bound on the random number to be returned. Must be positive.
    
    返回:
    the next value
    
    抛出:
    
    java.lang.IllegalArgumentException - if n is not positive
  - nextLong
```
public long nextLong(long least,
            long bound)
```
    Returns a pseudorandom, uniformly distributed value between the given least value (inclusive) and bound (exclusive).
    
    参数:
    least - the least value returned
    bound - the upper bound (exclusive)
    
    返回:
    the next value
    
    抛出:
    
    java.lang.IllegalArgumentException - if least greater than or equal to bound
  - nextDouble
```
public double nextDouble(double n)
```
    Returns a pseudorandom, uniformly distributed double value between 0 (inclusive) and the specified value (exclusive).
    
    参数:
    n - the bound on the random number to be returned. Must be positive.
    
    返回:
    the next value
    
    抛出:
    
    java.lang.IllegalArgumentException - if n is not positive
  - nextDouble
```
public double nextDouble(double least,
                double bound)
```
    Returns a pseudorandom, uniformly distributed value between the given least value (inclusive) and bound (exclusive).
    
    参数:
    least - the least value returned
    bound - the upper bound (exclusive)
    
    返回:
    the next value
    
    抛出:
    
    java.lang.IllegalArgumentException - if least greater than or equal to bound

类 ThreadLocalRandom

字段概要

构造器概要

方法概要

从类继承的方法 java.util.Random

从类继承的方法 java.lang.Object

字段详细资料

multiplier

addend

mask

rnd

initialized

pad0

pad1

pad2

pad3

pad4

pad5

pad6

pad7

localRandom

serialVersionUID

构造器详细资料

ThreadLocalRandom

方法详细资料

current

setSeed

next

nextInt

nextLong

nextLong

nextDouble

nextDouble