举一个java死锁的例子

一个经典的 Java 死锁例子是当两个或多个线程彼此持有对方所需的锁时。例如，当线程 A 拥有锁 L1，并且试图获取锁 L2 时，但在同一时间，线程 B 拥有锁 L2，并且试图获取锁 L1。这个情况下，两个线程将永远等待，产生死锁。以下是一个简单的 Java 代码示例：

class DeadlockExample {
    Object lock1 = new Object();
    Object lock2 = new Object();

    Thread thread1 = new Thread(new Runnable() {
        @Override
        public void run() {
            synchronized (lock1) {
                System.out.println("Thread1: Holding lock1...");

                try { Thread.sleep(10); }
                catch (InterruptedException e) {}

                System.out.println("Thread1: Waiting for lock2...");

                synchronized (lock2) {
                    System.out.println("Thread1: Holding lock1 and lock2...");
                }
            }
        }
    });

    Thread thread2 = new Thread(new Runnable() {
        @Override
        public void run() {
            synchronized (lock2) {
                System.out.println("Thread2: Holding lock2...");

                try { Thread.sleep(10); }
                catch (InterruptedException e) {}

                System.out.println("Thread2: Waiting for lock1...");

                synchronized (lock1) {
                    System.out.println("Thread2: Holding lock1 and lock2...");
                }
            }
        }
    });

    public static void main(String[] args) {
        DeadlockExample dle = new DeadlockExample();
        dle.thread1.start();
        dle.thread2.start();
    }
}

在这个例子中，两个线程分别拥有 lock1 和 lock2，但是他们都试图获取对方的锁，从而导致了死锁。