Java: Ví dụ lớp TopLevelDemo

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

/* TopLevelDemo.java không yêu cầu file ngoài. */

public class TopLevelDemo {

    /**

     * Create the GUI and show it.  For thread safety,

     * this method should be invoked from the

     * event-dispatching thread.

     */

    private static void createAndShowGUI() {

        //Create and set up the window.

        JFrame frame = new JFrame("TopLevelDemo");

        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //Create the menu bar.  Make it have a green background.

        JMenuBar greenMenuBar = new JMenuBar();

        greenMenuBar.setOpaque(true);

        greenMenuBar.setBackground(new Color(154, 165, 127));

        greenMenuBar.setPreferredSize(new Dimension(200, 20));

        //Create a yellow label to put in the content pane.

        JLabel yellowLabel = new JLabel();

        yellowLabel.setOpaque(true);

        yellowLabel.setBackground(new Color(248, 213, 131));

        yellowLabel.setPreferredSize(new Dimension(200, 180));

        //Set the menu bar and add the label to the content pane.

        frame.setJMenuBar(greenMenuBar);

        frame.getContentPane().add(yellowLabel, BorderLayout.CENTER);

        //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();

            }

        });

    }

}