What are some examples of deadlock in Java?

What are some examples of deadlock in Java?

Deadlock in Java occurs when two or more threads are blocked forever, each waiting for the other to release a resource. A classic example is when Thread A holds Resource 1 and waits for Resource 2, while Thread B holds Resource 2 and waits for Resource 1.

Can you give me a code example of this?

Sure! Here's a simple example:

class Resource {
    public synchronized void hold(Resource other) {
        System.out.println(Thread.currentThread().getName() + " holding " + this);
        other.hold(this);
    }
}

public class DeadlockExample {
    public static void main(String[] args) {
        final Resource resource1 = new Resource();
        final Resource resource2 = new Resource();

        Thread thread1 = new Thread(() -> resource1.hold(resource2), "Thread 1");
        Thread thread2 = new Thread(() -> resource2.hold(resource1), "Thread 2");

        thread1.start();
        thread2.start();
    }
}

This code can lead to a deadlock situation.

How can I prevent deadlock in my Java applications?

To prevent deadlock, you can follow these strategies: 1) Avoid nested locks, 2) Use a timeout when trying to acquire locks, and 3) Implement a lock hierarchy to ensure that all threads acquire locks in a consistent order.