Java Thread notifyAll()方法

Thread類的notifyAll()方法用於喚醒所有線程。此方法向特定對象的所有等待線程發出通知。

如果使用notifyAll()方法並且多個線程正在等待通知，那麼所有線程都會收到通知，但線程的執行將逐個執行，因為線程需要鎖定，並且只有一個鎖可用於一個對象。

語法

public final void notifyAll()

返回
此方法不返回任何值。

異常

• IllegalMonitorStateException ：如果當前線程不是對象監視器的所有者，則拋出此異常。

示例

class Notify1 extends Thread
{
    public void run()
    {
        synchronized(this)
        {
            System.out.println("Starting of " + Thread.currentThread().getName());
            try {
                this.wait();
            }
            catch (InterruptedException e) {
                e.printStackTrace();}
            System.out.println(Thread.currentThread().getName() + "...notified");
        }
    }
}
class Notify2 extends Thread {
    Notify1 notify1;
    Notify2(Notify1 notify1)
    {
        this.notify1 = notify1;
    }
    public void run()
    {
        synchronized(this.notify1)
        {
            System.out.println("Starting of " + Thread.currentThread().getName());
            try {
                this.notify1.wait();
            }
            catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println(Thread.currentThread().getName() + "...notified");
        }
    }
}
class Notify3 extends Thread
{
    Notify1 notify1;
    Notify3(Notify1 notify1)
    {
        this.notify1 = notify1;
    }
    public void run()
    {
        synchronized(this.notify1)
        {
            System.out.println("Starting of " + Thread.currentThread().getName());
            // call the notifyAll() method
            this.notify1.notifyAll();
            System.out.println(Thread.currentThread().getName() + "...notified");
        }
    }
}
public class JavaNotifyAllExp
{
    public static void main(String[] args) throws InterruptedException
    {
        Notify1 notify1 = new Notify1();
        Notify2 notify2 = new Notify2(notify1);
        Notify3 notify3 = new Notify3(notify1);

        // creating the threads
        Thread t1 = new Thread(notify1, "Thread-1");
        Thread t2 = new Thread(notify2, "Thread-2");
        Thread t3 = new Thread(notify3, "Thread-3");

        // call run() method
        t1.start();
        t2.start();
        Thread.sleep(100);
        t3.start();
    }
}

執行上面示例代碼，得到以下結果：

Starting of Thread-1
Starting of Thread-2
Starting of Thread-3
Thread-3...notified
Thread-2...notified
Thread-1...notified