java 多线程：线程死锁,如何判断程序是否有死锁代码块儿

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();
    }
}