📅 最后修改于: 2020-11-15 03:52:19 🧑 作者: Mango
java.util.concurrent.ThreadLocalRandom是从jdk 1.7开始引入的实用程序类，在需要多个线程或ForkJoinTasks生成随机数时很有用。与Math.random()方法相比，它可以提高性能并且减少争用。
以下是ThreadLocalRandom类中可用的重要方法的列表。
| Sr.No. | Method & Description |
|---|---|
| 1 |
public static ThreadLocalRandom current() Returns the current thread’s ThreadLocalRandom. |
| 2 |
protected int next(int bits) Generates the next pseudorandom number. |
| 3 |
public double nextDouble(double n) Returns a pseudorandom, uniformly distributed double value between 0 (inclusive) and the specified value (exclusive). |
| 4 |
public double nextDouble(double least, double bound) Returns a pseudorandom, uniformly distributed value between the given least value (inclusive) and bound (exclusive). |
| 5 |
public int nextInt(int least, int bound) Returns a pseudorandom, uniformly distributed value between the given least value (inclusive) and bound (exclusive). |
| 6 |
public long nextLong(long n) Returns a pseudorandom, uniformly distributed value between 0 (inclusive) and the specified value (exclusive). |
| 7 |
public long nextLong(long least, long bound) Returns a pseudorandom, uniformly distributed value between the given least value (inclusive) and bound (exclusive). |
| 8 |
public void setSeed(long seed) Throws UnsupportedOperationException. |
下面的TestThread程序演示了Lock接口的其中一些方法。在这里，我们使用了lock()来获取锁，然后使用unlock()来释放锁。
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)
在这里，我们使用了ThreadLocalRandom和Random类来获取随机数。