Java Thread enumerate()方法

Thread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。

此方法使用activeCount方法来估计数组应该有多大。 如果数组的长度太短而无法容纳所有线程，则会以静默方式忽略额外的线程。

语法

public static int enumerate(Thread[] tarray)

参数

• tarray ：此方法是要复制到的Thread对象数组。

返回
此方法返回放入数组的线程数。

示例

public class JavaEnumerateExp extends Thread   
{  
    JavaEnumerateExp(String threadname, ThreadGroup tg)  
    {  
        super(tg, threadname);  
        start();  
    }  
    public void run()  
    {  
        for (int i = 0; i < 5; i++)   
        {  
            try  
            {  
                Thread.sleep(10);  
            }     
            catch (InterruptedException ex) {  
                System.out.println("Exception encounterted");}  
        }  
        System.out.println(Thread.currentThread().getName() +" completed executing");  
    }  
    public static void main(String arg[]) throws InterruptedException,SecurityException  
    {  
        // 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   
        JavaEnumerateExp t1 = new JavaEnumerateExp("Thread-1", g1);  
        System.out.println("Starting of Thread-1");  
        // creating another thread   
        JavaEnumerateExp t2 = new JavaEnumerateExp("Thread-2", g1);  
        System.out.println("Starting of Thread-2");  

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

        // prints active threads  
        for (int i = 0; i < count; i++)   
        {  
            System.out.println(group[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