java多线程-- 死锁模拟( synchronized )

•  化妆需要镜子,口红
  

•  两个人分别拿到镜子和口红,谁都不让谁,都想拿到对方手里的资源
  

•  就造成了死锁的问题
  

程序一直处于等待状态

package cn.usts.edu.lesson07;



public class DeadLock {
    public static void main(String[] args) {
        MakeUp makeUp1 = new MakeUp(0,"白雪公主");
        MakeUp makeUp2 = new MakeUp(1,"灰姑娘");
        new Thread(makeUp1).start();
        new Thread(makeUp2).start();
    }
}

// 口红
class Lipstick{

}

// 镜子
class Mirror{

}

// 化妆
class MakeUp implements Runnable {

    // 资源只有一份,用static修饰
    static final Lipstick lipstick = new Lipstick();
    static final Mirror mirror = new Mirror();

    int choice;
    String name;

    MakeUp(int choice,String name){
        // choice = 0;先拿镜子,
        // choice = 1;先拿口红
        this.choice = choice;
        this.name = name;
    }

    private void makeup() throws InterruptedException {
        if (choice==0){
            synchronized (lipstick){
                System.out.println(name+"拿到了口红,上了锁,别人不许用,还想要镜子");
                Thread.sleep(1000);
                synchronized (mirror){
                    System.out.println(name+"拿到了镜子的锁,别人不许用,现在我都拿到,化完妆了");
                }
            }

        }else {
            synchronized (mirror){
                System.out.println(name+"拿到了镜子,上了锁,别人不许用,还想要口红");
                Thread.sleep(2000);
                synchronized (lipstick){
                    System.out.println(name+"拿到了口红的锁,别人不许用,现在我都拿到,化完妆了");
                }
            }
        }
    }


    @Override
    public void run() {
        try {
            makeup();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

依次获取资源, 一个目标不能同时拿到两个把锁

package cn.usts.edu.lesson07;



public class DeadLock {
    public static void main(String[] args) {
        MakeUp makeUp1 = new MakeUp(0,"白雪公主");
        MakeUp makeUp2 = new MakeUp(1,"灰姑娘");
        new Thread(makeUp1).start();
        new Thread(makeUp2).start();
    }
}

// 口红
class Lipstick{

}

// 镜子
class Mirror{

}

// 化妆
class MakeUp implements Runnable {

    // 资源只有一份,用static修饰
    static final Lipstick lipstick = new Lipstick();
    static final Mirror mirror = new Mirror();

    int choice;
    String name;

    MakeUp(int choice,String name){
        // choice = 0;先拿镜子,
        // choice = 1;先拿口红
        this.choice = choice;
        this.name = name;
    }

    private void makeup() throws InterruptedException {
        if (choice==0){
            synchronized (lipstick){
                System.out.println(name+"拿到了口红,上了锁");
                Thread.sleep(5000);
            }

            System.out.println(name+"口红使用完了,我还想用镜子");

            synchronized (mirror){
                System.out.println(name+"拿到了镜子,上了锁,我口红和镜子都用完了.化完妆了");
            }
        }
        else {
            synchronized (mirror){
                System.out.println(name+"拿到了镜子,上了锁,还想要口红");
                Thread.sleep(7000);
            }

            System.out.println(name+"镜子使用完了,我还想用口红");

            synchronized (lipstick){
                System.out.println(name+"拿到了口红的锁,别人不许用,我口红和镜子都用完了,化完妆了");
            }
        }
    }


    @Override
    public void run() {
        try {
            makeup();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}