Java Object notifyAll() 方法

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Object notifyAll() 方法用于唤醒在该对象上等待的所有线程。

notifyAll() 方法跟 notify() 方法一样，区别在于 notifyAll() 方法唤醒在此对象监视器上等待的所有线程，notify() 方法是一个线程。

如果当前线程不是对象监视器的所有者，那么调用 notifyAll() 方法同样会发生 IllegalMonitorStateException 异常。

语法

public final void notifyAll()

参数

• 无 。

返回值

没有返回值。

实例

以下实例演示了 notifyAll() 方法的使用：

import java.util.Collections;
import java.util.LinkedList;
import java.util.List;
 
public class LectcodeTest {
private List synchedList;
 
    public LectcodeTest() {
// 创建一个同步列表
synchedList = Collections.synchronizedList(new LinkedList());
    }
// 删除列表中的元素
public String removeElement() throws InterruptedException {
synchronized (synchedList) {
// 列表为空就等待
while (synchedList.isEmpty()) {
System.out.println("List is empty...");
                synchedList.wait();
                System.out.println("Waiting...");
            }
String element = (String) synchedList.remove(0);
 
            return element;
        }
}
// 添加元素到列表
public void addElement(String element) {
System.out.println("Opening...");
        synchronized (synchedList) {
// 添加一个元素，并通知元素已存在
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 LectcodeTest demo = new LectcodeTest();
 
        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() {
// 执行添加元素操作，并开始循环
public void run() {
demo.addElement("Hello!");
            }
};
 
        try {
Thread threadA1 = new Thread(runA, "Google");
            threadA1.start();
 
            Thread.sleep(500);
 
            Thread threadA2 = new Thread(runA, "Lectcode");
            threadA2.start();
 
            Thread.sleep(500);
 
            Thread threadB = new Thread(runB, "Taobao");
            threadB.start();
 
            Thread.sleep(1000);
 
            threadA1.interrupt();
            threadA2.interrupt();
        } catch (InterruptedException x) {
}
}
}

以上程序执行结果为：

List is empty...

List is empty...

Opening...

New Element:'Hello!'

notifyAll called!

Closing...

Waiting...

Waiting...

List is empty...

Hello!

Interrupted Exception!