死锁是由于 “同步块需要同时持有多个对象锁造成”的，要解决这个问题，思路很简单， 就是：同一个代码块，不要同时持有两个对象锁

package com.yqq.app12;

/**
 * @Author yqq
 * @Date 2021/11/28 23:14
 * @Version 1.0
 */

import lombok.Setter;

/**
 * 口红类
 */
class Lipstick{

}

/**
 * 镜子类
 */
class Mirror{

}

/**
 * 化妆线程类
 */
@Setter
class Makeup extends Thread{
    private int flag;//flag=0:拿着口红，flag!=0:拿着镜子
    private String girlName;
    static  Lipstick lipstick = new Lipstick();
    static Mirror mirror = new Mirror();

    @Override
    public void run() {
        this.doMakeup();
    }
    /**
     * 开始化妆
     */
    public void doMakeup(){
        if (flag == 0){
            synchronized (lipstick){
                System.out.println(this.girlName+" 拿着口红");
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            synchronized (mirror){
                System.out.println(this.girlName+" 拿着镜子");
            }
        }else {
            synchronized (mirror){
                System.out.println(this.girlName+" 拿着镜子");
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            synchronized (lipstick){
                System.out.println(this.girlName+" 拿着口红");
            }
        }
    }
}
public class DeadLockThread {
    public static void main(String[] args) {
        Makeup makeup = new Makeup();
        makeup.setFlag(0);
        makeup.setGirlName("瓦妮莎");
        Makeup makeup1 = new Makeup();
        makeup1.setFlag(1);
        makeup1.setGirlName("刘亦菲");
        makeup.start();
        makeup1.start();
    }
}

线程死锁问题的解决_子类