Java ThreadGroup enumerate()方法

ThreadGroup类的enumerate()方法用于将每个活动线程的线程组及其子组复制到指定的数组中。 此方法使用tarray参数调用`enumerate()方法。

语法

public int enumerate(Thread[] tarray)

参数

• tarray:它是要复制到的Thread对象数组。

返回

此方法返回放入数组的线程数。

package com.zaixian.threadgroup;

class NewThread extends Thread {
    NewThread(String threadname, ThreadGroup tg) {
        super(tg, threadname);
    }

    public void run() {
        for (int i = 0; i < 10; i++) {
            try {
                Thread.sleep(10);
            } catch (InterruptedException ex) {
                System.out.println(Thread.currentThread().getName() + " interrupted");
            }
        }
        System.out.println(Thread.currentThread().getName() + " completed executing");
    }
}

public class ThreadGroupEnumerateExp {
    public static void main(String arg[]) {
        // creating the ThreadGroup
        ThreadGroup g1 = new ThreadGroup("Parent thread");
        // creating a child ThreadGroup for parent ThreadGroup
        ThreadGroup g2 = new ThreadGroup(g1, "child thread");

        // creating a thread
        NewThread t1 = new NewThread("Thread-1", g1);
        System.out.println("Starting of Thread-1");
        t1.start();
        // creating another thread
        NewThread t2 = new NewThread("Thread-2", g1);
        System.out.println("Starting of Thread-2");
        t2.start();

        // returns the number of threads put into the array
        Thread[] tarray = new Thread[g1.activeCount()];
        int count = g1.enumerate(tarray);

        // prints active threads
        for (int i = 0; i < count; i++)
            System.out.println(tarray[i].getName() + " found");
    }
}

执行上面示例代码，得到以下结果:

Starting of Thread-1
Starting of Thread-2
Thread-1 found
Thread-2 found
Thread-1 completed executing
Thread-2 completed executing