How do I implement reentrant functions in Java?

How do I implement reentrant functions in Java?

Reentrant functions are those that can be interrupted and safely called again before the previous executions complete. In Java, you can implement them using synchronized blocks or methods. Would you like an example?

Yes, please provide an example of a reentrant function.

Sure! Here's a simple example:

public class ReentrantExample {
    private int count = 0;

    public synchronized void increment() {
        count++;
        System.out.println("Count: " + count);
    }
}

In this example, the increment method is synchronized, making it reentrant. If it's called again while it's still executing, it will wait until the first call is complete.

What if I need to use it in a multi-threaded environment?

In a multi-threaded environment, you can use ReentrantLock from the java.util.concurrent.locks package. It provides more flexibility than synchronized methods. Would you like to see how to use it?

Yes, that would be great!

Here's how you can use ReentrantLock:

import java.util.concurrent.locks.ReentrantLock;

public class ReentrantLockExample {
    private final ReentrantLock lock = new ReentrantLock();
    private int count = 0;

    public void increment() {
        lock.lock();
        try {
            count++;
            System.out.println("Count: " + count);
        } finally {
            lock.unlock();
        }
    }
}

This ensures that even in a multi-threaded environment, your increment method remains safe and reentrant.