Java ThreadGroup isDestroyed()用法及代碼示例

ThreadGroup類isDestroyed()方法

• isDestroyed() 方法在 java.lang 包中可用。
• isDestroyed() 方法用於檢查這個線程組是否已經被銷毀或未被銷毀。
• isDestroyed() 方法是一個非靜態方法，它隻能通過類對象訪問，如果我們嘗試使用類名訪問方法，那麽我們將得到一個錯誤。
• isDestroyed() 方法在檢查該線程組的銷毀行為時不拋出異常。

用法:

    public boolean isDestroyed();

參數：

• 它不接受任何參數。

返回值：

這個方法的返回類型是Boolean– 當這個線程組被銷毀時返回真，否則返回假。

例：

// Java program to demonstrate the example 
// of boolean isDestroyed()method of ThreadGroup 

public class Destroy implements Runnable {
    public static void main(String[] args) {
        Destroy des = new Destroy();
        des.destroy();
    }

    public void destroy() {
        try {
            // Create two thread group and the named are base
            // and derived

            ThreadGroup base = new ThreadGroup("Base ThreadGroup");
            ThreadGroup derived = new ThreadGroup(base, "Derived ThreadGroup");

            // create two threads
            Thread th1 = new Thread(base, this);
            Thread th2 = new Thread(derived, this);

            // By using getName() method is to retrieve the
            // name of the thread th1
            System.out.println(th1.getName() + " " + "begins.....");

            // By using start() method is to start its execution 
            // of thread th1
            th1.start();

            // By using getName() method is to retrieve the
            // name of the thread th2
            System.out.println(th2.getName() + " " + "begins.....");

            // By using start() method is to start its execution 
            // of thread th2
            th2.start();

            // By using join() method is to wait the current
            // thread till complete execution of another
            // thread

            th1.join();
            th2.join();

            System.out.println();
            // By using isDestroyed() method is to check the
            // destroy status of the thread group
            boolean b1 = base.isDestroyed();
            boolean b2 = derived.isDestroyed();

            System.out.println("Is" + " " + base.getName() + "destroyed:" + " " + b1);
            System.out.println("Is" + " " + derived.getName() + "destroyed:" + " " + b2);
        } catch (InterruptedException ex) {
            ex.printStackTrace();
        }
    }

    // Override run()
    public void run() {
        for (int k = 0; k < 100; ++k)
            ++k;
        System.out.println(Thread.currentThread().getName() + " " + "ends.....");
    }
}

輸出

Thread-0 begins.....
Thread-1 begins.....
Thread-0 ends.....
Thread-1 ends.....

Is Base ThreadGroupdestroyed:false
Is Derived ThreadGroupdestroyed:false