17. Anonymous Inner Classes: On-the-Fly

Scenario

Sometimes you need a class just once. Instead of creating a new .java file, you can extend a class or implement an interface "on-the-fly".

Code Block

abstract class Button {
    abstract void onClick();
}

public class Main {
    public static void main(String[] args) {
        // Creating an anonymous subclass of Button
        Button loginBtn = new Button() {
            @Override
            void onClick() {
                System.out.println("User Logged In!");
            }
        };

        loginBtn.onClick();
        System.out.println("Class Name: " + loginBtn.getClass().getName());
    }
}

Take Your Shot

Predicted Output

Type exactly what you think will be printed in the console.