Java.lang.Object.notifyAll() 方法

描述

java.lang.Object.notifyAll() 唤醒所有在这个对象的监视器上等待的线程。 线程通过调用其中一个等待方法在对象的监视器上等待。

在当前线程放弃对该对象的锁定之前，被唤醒的线程将无法继续。 被唤醒的线程将以通常的方式与可能正在积极竞争以在该对象上同步的任何其他线程竞争； 例如，被唤醒的线程在成为下一个锁定该对象的线程方面没有任何可靠的特权或劣势。

该方法只能由作为该对象监视器所有者的线程调用。

声明

以下是 java.lang.Object.notifyAll() 方法的声明。

public final void notifyAll()

参数

NA

返回值

此方法不返回值。

异常

IllegalMonitorStateException − 如果当前线程不是该对象监视器的所有者。

示例

下面的例子展示了 lang.Object.notifyAll() 方法的使用。

package com.tutorialspoint;

import java.util.Collections;
import java.util.LinkedList;
import java.util.List;

public class ObjectDemo extends Object {

   private List synchedList;

   public ObjectDemo() {
      // create a new synchronized list to be used
      synchedList = Collections.synchronizedList(new LinkedList());
   }

   // method used to remove an element from the list
   public String removeElement() throws InterruptedException {
      synchronized (synchedList) {

         // while the list is empty, wait
         while (synchedList.isEmpty()) {
            System.out.println("List is empty...");
            synchedList.wait();
            System.out.println("Waiting...");
         }
         String element = (String) synchedList.remove(0);

         return element;
      }
   }

   // method to add an element in the list
   public void addElement(String element) {
      System.out.println("Opening...");
      synchronized (synchedList) {

         // add an element and notify all that an element exists
         synchedList.add(element);
         System.out.println("New Element:'" + element + "'");

         synchedList.notifyAll();
         System.out.println("notifyAll called!");
      }
      System.out.println("Closing...");
   }

   public static void main(String[] args) {
      final ObjectDemo demo = new ObjectDemo();

      Runnable runA = new Runnable() {

         public void run() {
            try {
               String item = demo.removeElement();
               System.out.println("" + item);
            } catch (InterruptedException ix) {
               System.out.println("Interrupted Exception!");
            } catch (Exception x) {
               System.out.println("Exception thrown.");
            }
         }
      };

      Runnable runB = new Runnable() {

         // run adds an element in the list and starts the loop
         public void run() {
            demo.addElement("Hello!");
         }
      };

      try {
         Thread threadA1 = new Thread(runA, "A");
         threadA1.start();

         Thread.sleep(500);

         Thread threadA2 = new Thread(runA, "B");
         threadA2.start();

         Thread.sleep(500);

         Thread threadB = new Thread(runB, "C");
         threadB.start();

         Thread.sleep(1000);

         threadA1.interrupt();
         threadA2.interrupt();
      } catch (InterruptedException x) {
      }
   }
}

让我们编译并运行上面的程序，这将产生下面的结果 −

List is empty...
List is empty...
Opening...
New Element:'Hello!'
notifyAll called!
Closing...
Waiting...
Hello!
Waiting...
List is empty...
Interrupted Exception!