What is the Callable interface in Java?

The Callable interface in Java represents a task that can be executed in a separate thread and returns a result. Unlike Runnable, which does not return a value and cannot throw checked exceptions, Callable<V> returns an object of type V and can throw exceptions.

Main features:

• The call() method returns the execution result.
• Can be used with ExecutorService for asynchronous task execution and obtaining results via Future.

Example usage:

import java.util.concurrent.*;

public class CallableExample {
    public static void main(String[] args) throws Exception {
        ExecutorService executor = Executors.newSingleThreadExecutor();

        Callable<Integer> task = () -> {
            // Some computational task
            Thread.sleep(1000);
            return 42;
        };

        Future<Integer> future = executor.submit(task);

        // Can perform other operations

        Integer result = future.get(); // blocks until the task completes
        System.out.println("Result: " + result);

        executor.shutdown();
    }
}