Using Top-Level Containers in Java

[taher]

Hi,
I am confused while using the containers in Java. I have recently started doing the Java and completed some of the basic programs. I thought that posting my doubt over here can help me in solving the confusion.!! so please tell me how to use Top-Level Containers in Java.?? Any coding related to the topic would be grateful for me..!!
thanks in advance.!!

[CodGuru]

All elements of a user interface must be added to the content pane of a top-level container in Java 2. Also you should know that each program that uses Swing components has at least one top-level container. The top-level container is the hierarchy that contains all of the Swing components that appear inside the top-level container. You can also set the content pane to a new JPanel (but not a split, tabbed, or scroll pane) with myFrame.setContentPane(myPanel) by adding components to myPanel.

[Allan.d]

Normally, you will use three types of the top-level containers. They are as follows :

• Dialogs can easily be created. Methods in the Toolkit class should be used to get a print dialog.
• Windows (JFrame) have a title bar with close and iconifying buttons.
• Applets

[Modifier]

You can use the following coding for the top-level container :

package components;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class TopLevelDemo {

    private static void createAndShowGUI() {
        JFrame frame = new JFrame("TopLevelTrial");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JMenuBar greenMenuBar = new JMenuBar();
        greenMenuBar.setOpaque(true);
        greenMenuBar.setBackground(new Color(204, 157, 142));
        greenMenuBar.setPreferredSize(new Dimension(140, 28));

        JLabel yellowLabel = new JLabel();
        yellowLabel.setOpaque(true);
        yellowLabel.setBackground(new Color(148, 103, 211));
        yellowLabel.setPreferredSize(new Dimension(107, 150));

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

        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
}

[Reegan]

If you want to make a component the content pane, then you would have to use the top-level container's setContentPane method. You can see an example that I have mentioned below :

JPanel contentPane = new JPanel(new BorderLayout());
    contentPane.setBorder(someBorder);
    contentPane.add(someComponent, BorderLayout.CENTER);
    contentPane.add(anotherComponent, BorderLayout.PAGE_END);


    topLevelContainer.setContentPane(contentPane);