Thread: keyword Extends

 public class KeyWordExtends extends JFrame {
 
 
    public void bla () {
 
        setSize(400, 500);
        setVisible(true);
    }
 
    public static void main(String[] args) {
 
        KeyWordExtends extend = new KeyWordExtends();
        extend.bla();
    }
}

the class KeyWordExtends is a subclass of the JFrame?

does it mean . that this class is an INSTANCE of the JFrame class?

so thats why this class shows a JFrame window.....
without declaring an object for the JFrame?


and how bout this one

public class NewClass extends JFrame {
 
    JFrame frame;
    JButton button;
    JPanel panel;
 
    public void sample() {
 
        frame = new JFrame("Sample");
 
        frame.setDefaultCloseOperation(NewClass.EXIT_ON_CLOSE); // is this a new class of the JFrame class?
        frame.setSize(500, 500);
        frame.setVisible(true);
        frame.getContentPane().add(panel);
    }
 
    public static void main(String[] args) {
 
        NewClass object = new NewClass();
 
        object.sample();
    }
}

NewClass is a new class for the JFrame class?, so it can access any static methods or fields of the JFrame class?

 frame.setDefaultCloseOperation(NewClass.EXIT_ON_CLOSE); // is this a new class of the JFrame class?