线程间通信wait notfiy 方法，wait释放锁，notfiy不释放锁

先运行t2线程,t2线程处于等待中,再运行t1线程,当t1线程list等于5,会唤醒t2线程,但是t1线程,需要都处理完才会释放锁,所以不能够达到实时通信,
需要达到线程中实时通信要用到CountDownLatch类

import java.util.ArrayList;
import java.util.List;
/**
 * wait notfiy 方法，wait释放锁，notfiy不释放锁
 * @author alienware
 *
 */
public class ListAdd2 {
    private volatile static List list = new ArrayList();    

    public void add(){
        list.add("bjsxt");
    }
    public int size(){
        return list.size();
    }

    public static void main(String[] args) {

        final ListAdd2 list2 = new ListAdd2();

        // 1 实例化出来一个 lock
        // 当使用wait 和 notify 的时候 ， 一定要配合着synchronized关键字去使用
        final Object lock = new Object();


        Thread t1 = new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    synchronized (lock) {
                        for(int i = 0; i <10; i++){
                            list2.add();
                            System.out.println("当前线程：" + Thread.currentThread().getName() + "添加了一个元素..");
                            Thread.sleep(500);
                            if(list2.size() == 5){
                                System.out.println("已经发出通知..");
                                lock.notify();
                            }
                        }                       
                    }
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }

            }
        }, "t1");

        Thread t2 = new Thread(new Runnable() {
            @Override
            public void run() {
                synchronized (lock) {
                    if(list2.size() != 5){
                        try {
                            System.out.println("t2进入...");
                            lock.wait();
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }
                    System.out.println("当前线程：" + Thread.currentThread().getName() + "收到通知线程停止..");
                    throw new RuntimeException();
                }
            }
        }, "t2");   

        t2.start();
        t1.start();

    }

}