併發編程基礎之wait以及notify的用法

一：概念

線程通訊中常常用到wait和notify，顧名思義，wait即讓當前線程處於等待狀態，notify通知鎖對象

上的另外一個線程被喚醒，這裏的喚醒是指能夠去爭奪鎖資源，nofityAll是喚醒該對象上面全部處於

wait狀態的線程

 

二：示例

線程t2一運行就處於wait等待狀態，而後線程t1運行notify，喚醒線程t2

/**
 * 
 */
package com.day2;

/**
 * @author Administrator
 *
 */
public class NotifyWaitThreadDemo {

	private int count;

	public static void main(String[] args) {

		NotifyWaitThreadDemo demo = new NotifyWaitThreadDemo();

		Thread t1 = new Thread("t1") {
			public void run() {
				synchronized (demo) {
					for (int i = 0; i < 100; i++) {
						demo.count = i;
						if (demo.count == 50) {
							System.out.println(Thread.currentThread().getName()+"發出通知");
							demo.notify();
						}
					}
				}

			}
		};

		Thread t2 = new Thread("t2") {
			public void run() {
				while (true) {
					synchronized (demo) {
						System.out.println(Thread.currentThread().getName() + "開始等待");
						try {
							demo.wait();
						} catch (InterruptedException e) {
							e.printStackTrace();
						}
					}
					System.out.println(Thread.currentThread().getName() + "跳出等待");
					System.out.println("demo.count" + demo.count);
					break;
				}

			}
		};
		
		t2.start();
		try {
			Thread.sleep(100);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		t1.start();
		
	}
}

　　

若是還有一個線程t3也處於wait狀態，那麼t1線程若是想喚醒t1和t3，就須要使用notifyAll

/**
 * 
 */
package com.day2;

/**
 * @author Administrator
 *
 */
public class NotifyWaitThreadDemo {

	private int count;

	public static void main(String[] args) {

		NotifyWaitThreadDemo demo = new NotifyWaitThreadDemo();

		Thread t1 = new Thread("t1") {
			public void run() {
				synchronized (demo) {
					for (int i = 0; i < 100; i++) {
						demo.count = i;
						if (demo.count == 50) {
							System.out.println(Thread.currentThread().getName()+"發出通知");
							//demo.notify();
							demo.notifyAll();
						}
					}
				}

			}
		};

		Thread t2 = new Thread("t2") {
			public void run() {
				while (true) {
					synchronized (demo) {
						System.out.println(Thread.currentThread().getName() + "開始等待");
						try {
							demo.wait();
						} catch (InterruptedException e) {
							e.printStackTrace();
						}
					}
					System.out.println(Thread.currentThread().getName() + "跳出等待");
					System.out.println("demo.count" + demo.count);
					break;
				}

			}
		};
		
		Thread t3 = new Thread("t3") {
			public void run() {
				while (true) {
					synchronized (demo) {
						System.out.println(Thread.currentThread().getName() + "開始等待");
						try {
							demo.wait();
						} catch (InterruptedException e) {
							e.printStackTrace();
						}
					}
					System.out.println(Thread.currentThread().getName() + "跳出等待");
					break;
				}

			}
		};
		t2.start();
		t3.start();
		try {
			Thread.sleep(100);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		t1.start();
		
	}
}

　　

運行結果：

t2開始等待
t3開始等待
t1發出通知
t3跳出等待
t2跳出等待
demo.count99