Java死锁

package pnunu.DeadLock;

public class DeadLock1 {

    public static void main(String[] args) {
        Object o1 = new Object();
        Object o2 = new Object();
        Object o3 = new Object();
        Object o4 = new Object();
        Runnable r1 = new TT1(o1, o2);
        Runnable r2 = new TT2(o2, o3);
        Runnable r3 = new TT3(o3, o4);
        Runnable r4 = new TT4(o4, o1);
        Thread t1 = new Thread(r1, "r1");
        Thread t2 = new Thread(r2, "r2");
        Thread t3 = new Thread(r3, "r3");
        Thread t4 = new Thread(r4, "r4");
        System.out.println("哲学家进餐:");
        t1.start();
        t2.start();
        t3.start();
        //解决哲学家进餐问题
        /*
        try {
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        */
        t4.start();
    }
}

class TT1 implements Runnable{

    private Object o1;
    private Object o2;
    public TT1(Object o1,Object o2){
        this.o1 = o1;
        this.o2 = o2;
    }
    @Override
    public void run() {
        System.out.println(Thread.currentThread()+" 开始");
        synchronized (o1) {
            try{Thread.sleep(1000);}catch(Exception e){}
            synchronized (o2) {
                System.out.println(Thread.currentThread().getName()+"就餐");
            }
        }
        System.out.println(Thread.currentThread()+" 结束");
    }
    
}


class TT2 implements Runnable{

    private Object o1;
    private Object o2;
    public TT2(Object o1,Object o2){
        this.o1 = o1;
        this.o2 = o2;
    }
    @Override
    public void run() {
        System.out.println(Thread.currentThread()+" 开始");
        synchronized (o1) {
            try{Thread.sleep(1000);}catch(Exception e){}
            synchronized (o2) {
                System.out.println(Thread.currentThread().getName()+"就餐");
            }
        }
        System.out.println(Thread.currentThread()+" 结束");
    }
}


class TT3 implements Runnable{

    private Object o1;
    private Object o2;
    public TT3(Object o1,Object o2){
        this.o1 = o1;
        this.o2 = o2;
    }
    @Override
    public void run() {
        System.out.println(Thread.currentThread()+" 开始");
        synchronized (o1) {
            try{Thread.sleep(1000);}catch(Exception e){}
            synchronized (o2) {
                System.out.println(Thread.currentThread().getName()+"就餐");
            }
        }
        System.out.println(Thread.currentThread()+" 结束");
    }
}

class TT4 implements Runnable{

    private Object o1;
    private Object o2;
    public TT4(Object o1,Object o2){
        this.o1 = o1;
        this.o2 = o2;
    }
    @Override
    public void run() {
        System.out.println(Thread.currentThread()+" 开始");
        synchronized (o1) {
            try{Thread.sleep(1000);}catch(Exception e){}
            synchronized (o2) {
                System.out.println(Thread.currentThread().getName()+"就餐");
            }
        }
        System.out.println(Thread.currentThread()+" 结束");
    }
}

运行截图：