学步园

网上看到一个题目，要求3个线程依次打印ABC，并且循环10次，网上的版本比较多，这个是我实现的一个版本，共用一个Runnable对象，有点小缺陷，无法关联线程的名

字。

package com.mythread.test;

import java.util.concurrent.atomic.AtomicInteger;

public class TestAsynTreadXunlei {
	public static void main(String argv[]) {
		
		AtomicInteger synObj = new AtomicInteger(0);
		
		Runnable r = new PrintThread(synObj);
		
		try {
			Thread a = new Thread(r, "A");
			Thread b = new Thread(r, "B");
			Thread c = new Thread(r, "C");
			
			a.start();
			b.start();
			c.start();
			
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}

class PrintThread implements Runnable {

	private AtomicInteger synObj;
	
	public PrintThread(AtomicInteger synObj) {
		this.synObj = synObj;
	}
	
	@Override
	public void run() {
		print();
	}
	
	public void print() {
		for (int i = 0; i < 10; i++) {
			try {
				
				synchronized (synObj) {
					if (synObj.get() % 3 == 0) {
						System.out.println("A");
						synObj.set(synObj.get() + 1);
						synObj.notifyAll();
					} else if (synObj.get() % 3 == 1 ) {
						System.out.println("B");
						synObj.set(synObj.get() + 1);
						synObj.notifyAll();
					} else if (synObj.get() % 3 == 2 ) {
						System.out.println("C");
						synObj.set(synObj.get() + 1);
						synObj.notifyAll();
					} else {
						synObj.wait();
					}
				}
				
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
	}
}

网上比较经典的一个版本（基于thread）

package com.mythread.test;

import java.util.concurrent.atomic.AtomicInteger;

public class TestAsynTreadXunlei {
	public static void main(String argv[]) {
		
		AtomicInteger synObj = new AtomicInteger(0);
		
		TestPrint a = new TestPrint(synObj, "A", 0);
		TestPrint b = new TestPrint(synObj, "B", 1);
		TestPrint c = new TestPrint(synObj, "C", 2);
		
		a.start();
		b.start();
		c.start();
	}
}

class TestPrint extends Thread {
	
	private AtomicInteger synObj;
	private String name;
	private int flag;
	
	private int count = 0;
	
	public TestPrint(AtomicInteger synObj, String name, int flag) {
		this.synObj = synObj;
		this.name = name;
		this.flag = flag;
	}
	
	@Override
	public void run() {
		while (true) {
			synchronized (synObj) {
				if (synObj.get() % 3 == flag) {
					synObj.set(synObj.get() + 1);
					System.out.println(name);
					count++;
					synObj.notifyAll();
					if (count == 10) {
						break;
					}
				} else {
					try {
						synObj.wait();
					} catch (InterruptedException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
				}
			}
		}
	}
}