What is the difference between Callable and Runnable in Java?

What is the difference between Callable and Runnable in Java?

Callable and Runnable are both interfaces in Java used for concurrent programming. The main difference is that Callable can return a result and can throw checked exceptions, while Runnable cannot return a result and cannot throw checked exceptions.

Can you give an example of how to use Callable?

Sure! Here's a simple example:

import java.util.concurrent.Callable;
import java.util.concurrent.FutureTask;

public class CallableExample {
    public static void main(String[] args) throws Exception {
        Callable<Integer> task = () -> {
            return 123;
        };
        FutureTask<Integer> futureTask = new FutureTask<>(task);
        new Thread(futureTask).start();
        System.out.println("Result: " + futureTask.get());
    }
}

What about Runnable? Can you show me an example?

Of course! Here's an example of using Runnable:

public class RunnableExample {
    public static void main(String[] args) {
        Runnable task = () -> {
            System.out.println("Running in a thread!");
        };
        new Thread(task).start();
    }
}

When should I use Callable instead of Runnable?

You should use Callable when you need a task to return a result or when you need to handle checked exceptions. Runnable is suitable for tasks that do not require a return value.