Java ThreadGroup destroy()用法及代碼示例

ThreadGroup類destroy()方法

• destroy() 方法在 java.lang 包中可用。
• destroy() 方法用於銷毀這個線程組，當我們銷毀這個線程組時，它的子線程組將同時被銷毀。
• destroy() 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。
• destroy() 方法可能會在銷毀該線程組時拋出異常。
  • SecurityException – 當不允許當前線程更新此線程組時，可能會拋出此異常。
    • IllegalThreadStateException – 此異常可能在兩種情況下拋出
      • 當這個線程組已經被銷毀時。
      • 當此線程組不為空時。

用法:

    public final void destroy();

參數：

• 它不接受任何參數。

返回值：

這個方法的返回類型是void，它什麽都不返回。

例：

// Java program to demonstrate the example 
// of void destroy() method of ThreadGroup 

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

    public void destroyed() {
        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();

            System.out.println();

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

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

            // By using destroy() method is to
            // destroy the thread group named derived
            derived.destroy();
            boolean b1 = derived.isDestroyed();
            System.out.println(derived.getName() + " " + "destroyed" + " " + b1);

            boolean b2 = base.isDestroyed();
            System.out.println(base.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-0 ends.....
Thread-1 begins.....

Thread-1 ends.....
Derived ThreadGroup destroyed true
Base ThreadGroup destroyed false