多线程案例1：奇偶交替输出

尝试写了一个奇偶交替输出的demo，记录一下问题：

原来的线程类是如下：

package com.future.day0521;

public class demo1 {
    public static int num = 1;
    public static Object js = new Object();
    public static Object os = new Object();

    static class odd implements Runnable{

        public void run() {
            while (true){
                synchronized (js){
                    synchronized (os){
                        System.out.println("odd:"+num);
                        num++;
                        os.notifyAll();
                        try {
                            js.wait();
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }
                }
                Thread.yield();
            }
        }
    }

    static class even implements Runnable{

        public void run() {
            while (true){
                synchronized (os){
                    synchronized (js){
                        System.out.println("even:"+num);
                        num++;
                        js.notifyAll();
                        try {
                            os.wait();
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }
                }
                Thread.yield();
            }
        }
    }

    public static void main(String[] args) throws InterruptedException {
        Thread t1 = new Thread(new odd());
        Thread t2 = new Thread(new even());
        t1.start();
        Thread.sleep(10);
        t2.start();
    }
}

运行结果是，卡在了odd:1，使用visualvm软件，看到dump文件中是even线程blocking了，卡在了获取js的锁上，然后把odd类修改一下

static class odd implements Runnable{
        public void run() {
            while (true){
                synchronized (js){
                    synchronized (os){
                        System.out.println("odd:"+num);
                        num++;
                        os.notifyAll();
                    }
                    try {
                        js.wait();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
                Thread.yield();
            }
        }
    }

将js.wait移动到外面，代码就可以正常执行了。深入原因没有考虑，后面有时间研究一下