java - 程序不会导致死锁

Question

我试图在这个程序中实现死锁条件 这个程序没有给出死锁条件。为什么？ 请告诉我这段代码有什么问题。

输出是:

Thread1 : locked Integer
Thread2 : locked String
Thread1 : locked String
Thread2 : locked Integer

代码:

 class Dead {
    public void meth1() {
        synchronized (Integer.class) {
            System.out.println("Thread 1: locked Integer");
        }
        try {
            Thread.sleep(5000);
        } catch (InterruptedException e) {
            System.out.println(e);
        }
        synchronized (String.class) {
            System.out.println("Thread 1: locked String");
        }
    }

    public void meth2() {
        synchronized (String.class) {
            System.out.println("Thread 2: locked String");
        }
        try {
            Thread.sleep(5000);
        } catch (InterruptedException e) {
            System.out.println(e);
        }
        synchronized (Integer.class) {
            System.out.println("Thread 2: locked Integer");

        }
    }

}

class MThread1 extends Thread {
    Dead d;

    MThread1(Dead d) {
        this.d = d;
    }

    public void run() {
        d.meth1();
    }

}

class MThread2 extends Thread {

    Dead d;

    MThread2(Dead d) {
        this.d = d;
    }

    public void run() {
        d.meth2();
    }

}

public class Thread1 {
    public static void main(String[] args) {
        // Dead d = new Dead();
        MThread1 t1 = new MThread1(new Dead());
        MThread2 t2 = new MThread2(new Dead());
        t1.start();
        t2.start();
    }
}

Answer 1

当你写的时候

synchronized (Integer.class) {
            System.out.println("Thread 1: locked Integer");
        }

它锁定 Integer.class 对象并立即解锁它。你想要这个:

synchronized(Integer.class) {
    System.out.println("Thread 1: locked Integer");
    try {
        Thread.sleep(5000);
    } catch(InterruptedException e) {
        System.out.println(e);
    }
    synchronized(String.class) {
        System.out.println("Thread 1: locked String");
    }
}