import javax.swing.*;

public class HelloWorldSwing {

    private static void createAndShowGUI() {
        //Create and set up the window.
        JFrame frame = new JFrame("HelloWorldSwing");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //Add the ubiquitous "Hello World" label.
        JLabel label = new JLabel("Hello World");
        frame.getContentPane().add(label);

        //Display the window.
        frame.pack();
        frame.setVisible(true);
    }


    public static void main(String[] args) {
        //Schedule a job for the event-dispatching thread:
        //creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
}

import javax.swing.JFrame;
import javax.swing.JLabel;


public class HelloWorldFrame extends JFrame {

    //Programs entry point
    public static void main(String args[]) {
        new HelloWorldFrame();
    }

    //Class Constructor to create components
    HelloWorldFrame() {
        JLabel jlbHelloWorld = new JLabel("Hello World");
        add(jlbHelloWorld); //Add the label to the frame
        this.setSize(100, 100); //set the frame size
        setVisible(true); //Show the frame
    }
}