Runnable Interface

The Runnable interface in Java is another way to create and execute threads. It is preferred over extending the Thread class, especially when a class needs to extend another class as Java does not support multiple inheritance.

Declaring a Thread with Runnable

To use Runnable, implement the interface and pass the object to a Thread.

class MyRunnable implements Runnable {
    public void run() {
        System.out.println("Runnable thread running...");
    }
}

public class Main {
    public static void main(String[] args) {
        MyRunnable myRunnable = new MyRunnable();
        Thread t = new Thread(myRunnable);
        t.start();
    }
}

Advantages of Using Runnable

  • Decouples task from thread mechanics.
  • Allows class to extend another class.
  • More flexible in multithreaded applications.

Anonymous Runnable Example

public class Main {
    public static void main(String[] args) {
        Thread t = new Thread(new Runnable() {
            public void run() {
                System.out.println("Anonymous Runnable running...");
            }
        });
        t.start();
    }
}

Functional Interface & Lambda Expression (Java 8+)

public class Main {
    public static void main(String[] args) {
        Runnable r = () -> System.out.println("Lambda Runnable running...");
        Thread t = new Thread(r);
        t.start();
    }
}

🔗 Related Notes