java 多线程：线程死锁,如何判断程序是否有死锁代码块儿

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线程死锁

死锁是指两个或两个以上的线程在执行过程中，由于竞争资源或者由于彼此通信而造成的一种阻塞的现象，若无外力作用，它们都将无法推进下去（百度百科）。

代码示例：

/**

 * @ClassName ThreadDeadLock

 * @projectName: object1

 * @author: Zhangmingda

 * @description： XXX

 * date: 2021/4/22.

 */

public class ThreadDeadLock {

    private static class MyDeadLockRunnable implements Runnable{

        private Object lockA = new Object();

        private Object lockB = new Object();

        @Override

        public void run() {

            String tName = Thread.currentThread().getName();

            try {

                if ("A".equals(tName)){

                    runA();

                }else {

                    runB();

                }

            }catch (InterruptedException e){e.printStackTrace();}

        }

        private void runA() throws InterruptedException {

            synchronized (lockA){

                System.out.println("我开始运行了，我是A");

                Thread.sleep(1000);

                synchronized (lockB){

                    System.out.println("我运行完了，我是A");

                }

            }

        }

        private void runB() throws InterruptedException {

            synchronized (lockB){

                System.out.println("我开始运行了，我是B");

                Thread.sleep(1000);

                synchronized (lockA){

                    System.out.println("我运行完了，我是B");

                }

            }

        }

    }

    public static void main(String[] args) {

        Runnable myDeadlock = new MyDeadLockRunnable();

        new Thread(myDeadlock,"A").start();

        new Thread(myDeadlock,"B").start();

    }

}