スレッド通信(同期起動メカニズム)-生産者と消費者

package com.companyname;

public class Test {
	public static void main(String[] args) {
		Resource res=new Resource();
		Thread t1=new Thread(new Product(res));
		Thread t2=new Thread(new Product(res));
		Thread t3=new Thread(new Consumer(res));
		Thread t4=new Thread(new Consumer(res));
		t1.start();
		t2.start();
		t3.start();
		t4.start();
	}
}

class Resource {
	private int num = 0;
	private boolean flag=true;

	public synchronized void produce() {
		while (true) {
			if (flag) {
				System.out.println(Thread.currentThread().getName()+" ......."+(++num));
				flag=false;
			}
			else
			{
				this.notifyAll();    // 
				try {
					this.wait();    // 
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
			}
		}
	}
	public synchronized void consume() {
		while (true) {
			if(!flag){
				System.out.println(Thread.currentThread().getName()+" "+num);
				flag=true;
			}
			else
			{
				this.notifyAll();
				try {
					this.wait();
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
			}
		}
	}
}

class Product implements Runnable {
	private Resource res;

	public Product(Resource res) {
		this.res = res;
	}

	public void run() {
		res.produce(); //  
	}
}

class Consumer implements Runnable {
	private Resource res;

	public Consumer(Resource res) {
		this.res = res;
	}

	public void run() {
		res.consume(); //  
	}
}