Create panel depending on which tab is clicked in Swing

[Raymond Poon]

Depending on which tab is clicked in the JTabbedPane, a corresponding panel will be created.
I have created a simple test program as follows.

import java.awt.BorderLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTabbedPane;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;

JTabbedPane_Panel.java
public class JTabbedPane_Panel {
  static void add(JTabbedPane tabbedPane, String label) {
    JPanel panel = new JPanel();
    JButton okButton = new JButton("OK " + label);
    panel.add(okButton);
    JButton cancelButton = new JButton("Cancel " + label);
    panel.add(cancelButton);
    tabbedPane.addTab(label, panel);
  }

  public static void main(String args[]) {
    JFrame frame = new JFrame("Tabbed Pane Panel");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    JTabbedPane tabbedPane = new JTabbedPane();

    String titles[] = { "General", "Content", "Program"};
    for (int i = 0, n = titles.length; i < n; i++) {
      add(tabbedPane, titles[i]);
    }

    ChangeListener changeListener = new ChangeListener() {
      public void stateChanged(ChangeEvent changeEvent) {
        JTabbedPane sourceTabbedPane = (JTabbedPane) changeEvent.getSource();
        int index = sourceTabbedPane.getSelectedIndex();
        // debug output
        System.out.println("Tab changed to: " + sourceTabbedPane.getTitleAt(index));
      }
    };
    tabbedPane.addChangeListener(changeListener);
    frame.add(tabbedPane, BorderLayout.CENTER);
    frame.setSize(400, 150);
    frame.setVisible(true);
  }
}

Currently all the source code are in the same file.
I like to extract all the panel codes and put them in their own files like the following files.
How to do that?
Is this the correct approach or something should be done in ChangeListener?
Panel1.java

	    // what is the source code here?
	    //...
	    JPanel panel = new JPanel();
	    JButton okButton = new JButton("OK " + label);
	    panel.add(okButton);
	    JButton cancelButton = new JButton("Cancel " + label);
	    panel.add(cancelButton);
	    // what is the source code here?
	    //...

JTabbedPane_Panel.java

   //...
public class JTabbedPane_Panel {
  static void add(JTabbedPane tabbedPane, String label) {
 	    // what is the source code here?
	    //...
  }

   // ... the same source code here
  public static void main(String args[]) {
  // ...
  }
}

[Greg Brannon]

If you move the code that creates your panels from one file to their own, that suggests you will be creating new classes for each panel. So, to add those panels to your JTabbedPane, you would do something like:

tabbedPane.addTab("Tab 1", icon, new PanelOnePane( possible arguments ),
"Does nothing");

where PanelOnePane( possible arguments ) is a panel building class that you separated from your current single file that would extend JPanel.

Of course, you could instantiate the PanelOnePane before adding it to your tabbedPane with

PanelOnePane panelOnePane = new PanelOnePane( possible arguments );

Make sense?