java.util.concurrent.ThreadLocalRandom是从jdk 1.7开始引入的实用程序类,当需要多个线程或ForkJoinTasks生成随机数时非常有用.它比Math.random()方法提高了性能并减少了争用.
以下是ThreadLocalRandom中可用的重要方法列表class.
Sr.No. | 方法&说明 |
---|---|
1 | public static ThreadLocalRandom current() 返回当前线程的ThreadLocalRandom. |
2 | protected int next(int bits) 生成下一个伪随机数. |
3 | public double nextDouble(double n) 返回伪随机,均匀分布的double值0(含)和指定值(不包括). |
4 | public double nextDouble(double least,double bound) 返回一个均匀分布的伪随机数给定的最小值(包括)和约束(不包括)之间的值. |
5 | public int nextInt(int least,int bound) Ret urns伪随机,在给定的最小值(包括)和bound(不包括)之间均匀分布的值. |
6 | public long nextLong(long n) 返回0(包括)和指定值(不包括)之间的伪随机均匀分布值. |
7 | public long nextLong(long least, long bound) 返回给定最小值(包括)和bound(不包括)之间的伪随机均匀分布值. |
8 | public void setSeed(long seed) 抛出UnsupportedOperationException. |
以下TestThread程序演示了Lock接口的一些方法.这里我们使用lock()来获取锁定和解锁()以释放锁定.
import java.util.Random; import java.util.concurrent.locks.Condition; import java.util.concurrent.locks.Lock; import java.util.concurrent.locks.ReentrantLock; import java.util.concurrent.ThreadLocalRandom; public class TestThread { public static void main(final String[] arguments) { System.out.println("Random Integer: " + new Random().nextInt()); System.out.println("Seeded Random Integer: " + new Random(15).nextInt()); System.out.println( "Thread Local Random Integer: " + ThreadLocalRandom.current().nextInt()); final ThreadLocalRandom random = ThreadLocalRandom.current(); random.setSeed(15); //exception will come as seeding is not allowed in ThreadLocalRandom. System.out.println("Seeded Thread Local Random Integer: " + random.nextInt()); } }
这将产生以下结果.
Random Integer: 1566889198 Seeded Random Integer: -1159716814 Thread Local Random Integer: 358693993 Exception in thread "main" java.lang.UnsupportedOperationException at java.util.concurrent.ThreadLocalRandom.setSeed(Unknown Source) at TestThread.main(TestThread.java:21)
这里我们使用ThreadLocalRandom和Random类来获取随机数.