wait() notify使用注意事项

1.wait被调用之前notify的唤醒通知就来了，那么这个线程并不能保证被唤醒，有可能会导致死锁问题

2.不要使用if(队列size>最大个数) 否则真的会出现放入队列的size个数超过最大值的情况，推荐使用while

3.不要使用notify,推荐使用notifyall()

下面是生产者和消费者线程死锁方式和正确方式

package thred;import java.util.ArrayList;import java.util.List;import com.alibaba.fastjson.JSONObject;/** * 线程间通信 * 执行结果* @Description: TODO(用一句话描述该文件做什么) * @author min.zhang-2   * @date 2017年12月19日 上午9:39:53 * @version V1.0 */public class TestWaitNotify {public static void main(String[] args) {/*对应下面的注释1的类，如果生产者先过来，生产者想唤醒消费者，没有线程被阻塞唤醒结束消费者还没有被阻塞，这时候他请求过来，消费者线程被阻塞！！！！！执行结果：消费者等待吃苹果*//*String nameString  = "test";Coustem Coustem =  new Coustem(nameString);Producer Producer = new Producer(nameString);Coustem.start();Producer.start();*//*** * 实现了线程间通信的生产者和消费者，运行结果 *  *  使用notifyall()的时候 *  生产者生产了2个2["3","3"]消费者消费掉了一个1["3"]消费者消费掉了一个0[]消费者开始等待生产者生产了2个2["3","3"]消费者消费掉了一个1["3"]消费者消费掉了一个0[]消费者开始等待使用notify的时候，总是等待生产者满了等待之后才唤醒消费者，为啥呢？，所以推荐使用notifyall()生产者生产了2个2["3","3"]生产者生产了2个4["3","3","3","3"]生产者生产了2个6["3","3","3","3","3","3"]生产者生产了2个8["3","3","3","3","3","3","3","3"]生产者生产了2个10["3","3","3","3","3","3","3","3","3","3"]生产仓库已经满了10开始等待消费者消费掉了一个9["3","3","3","3","3","3","3","3","3"] */List<String> obList = new ArrayList<String>();Coustem Coustem =  new Coustem(obList);Producer Producer =  new Producer(obList);Producer.start();Coustem.start();}}/*****************这种方式就是死循环了*************//*class Coustem extends Thread{private Object lock;public Coustem(Object lock){this.lock=lock;}@Overridepublic void run() {synchronized(lock) {try {System.out.println("消费者等待吃苹果");lock.wait();} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}System.out.println("消费者部分结束");}}}class Producer extends Thread{private Object lock;public Producer(Object lock){this.lock=lock;}@Overridepublic void run() {synchronized(lock) {System.out.println("生产者生产了一个苹果");lock.notify();System.out.println("生产者部分结束");}}}*//*********************************对应main的第二段 ，实现了生产者消费者**********/class Producer extends Thread{private List<String> lock;public Producer(List<String> lock){this.lock=lock;}@Overridepublic void run() {while(true){synchronized(lock){while(lock.size() >= 10) {System.out.println("生产仓库已经满了"+lock.size()+"开始等待");try {lock.wait();} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}}lock.add("3");lock.add("3");System.out.println("生产者生产了2个"+lock.size()+JSONObject.toJSONString(lock));lock.notify();}}}}class Coustem extends Thread{private List<String> lock;public Coustem(List<String> lock){this.lock=lock;}@Overridepublic void run() {while(true){synchronized (lock) {while(lock.size() == 0) {System.out.println("消费者开始等待");try {lock.wait();} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}}lock.remove("3");System.out.println("消费者消费掉了一个"+lock.size()+JSONObject.toJSONString(lock));lock.notify();}}}}