JAVA多线程---两个线程交替运行

/**
 * 两个线程交替执行，a线程打印123，b线程打印456 和打印次数，执行结果是123456 0 123456 1   123456 2 ......
 * @author shangjie
 *
 */
public class TwoThreadLock {

	private static Object LOCK = new Object();
	private static boolean flag = false;
	
	public static void main(String[] args) {

		Thread b = new Thread() {
			public void run() {
				for (int c = 0; c <= 100; c++) {
					synchronized (LOCK) {
						for (int i = 4; i <= 6; i++) {
							System.out.print(i);
						}
						System.out.print(" " + c);
						System.out.println();
						if(flag){
							flag = false;
							LOCK.notify();
							if (c < 100) {
								try {
									LOCK.wait();
									
								} catch (InterruptedException e) {
									e.printStackTrace();
								}
							}
							
						}
					}

				}
			}
		};

		Thread a = new Thread() {
			public void run() {
				for (int c = 0; c <= 100; c++) {
					synchronized (LOCK) {
						for (int i = 1; i <= 3; i++) {
							System.out.print(i);
						}
						if(!flag){
							flag = true;
							LOCK.notify();//在这里虽然唤醒了另一个线程b，但锁并没有释放
							if (c < 100) {
								try {
									LOCK.wait();//在wait后的瞬间线程b得到锁
									
								} catch (InterruptedException e) {
									e.printStackTrace();
								}
							}
							
						}
					}
				}
			}
		};

		a.start();
		b.start();
	}
}

package com.mfz.test;

public class TwoThread {

	private static Object lock = new Object();
	private static boolean flag = false;
	
	public static void main(String[] args) {
		
		Thread a = new Thread(){
			public void run()
			{
				while(true)
				{
					synchronized(lock)
					{
						System.out.println("Thread1");
						
						if(flag)
						{
							flag = false;
							lock.notify();
							try {
								lock.wait();
							} catch (InterruptedException e) {
								// TODO Auto-generated catch block
								e.printStackTrace();
							}
						}
					}
					
					
				}
			}
		};
		
		Thread b = new Thread(){
			public void run()
			{
				while(true)
				{
					synchronized(lock)
					{
						System.out.println("Thread2");
						
						if(!flag)
						{
							flag =true;
							try {
								lock.notify();
								lock.wait();
							} catch (Exception e) {
								// TODO: handle exception
								e.printStackTrace();
							}
						}
					}
					
					
				}
			}
		};
		
		a.start();
		b.start();
	}
}

评论

2 楼 jeasonjack 2014-06-24  

zy52178580 写道

版主您好：
  想问下程序中flag的作用 拿掉可以么谢谢额

不可以，标识作用。

1 楼 zy52178580 2014-06-03  

版主您好：
  想问下程序中flag的作用 拿掉可以么谢谢额