Gui code design question ...

Question

Hi
I need some designtip. Im doing a gui with tabs. Due to lots of lines of code when setting up each tab, the gui class rows is now heading towards infinity. Additionally the actionperformed method from all the buttons, jtexts and textareas on the tabs ... is also growing towards infinity.
Simply put: I need design tips from the javamasters. Im quite bad at these kinds of design issues.
A subquestion is also if there is any tutorials/books/howtos on how to come up with excellent designs, making the coding sweet.
Thanks in advance !!!

Answer 1

Hello,
the topic of this thread is basically Gui code design. So, first of all, i recommend to understand the MVC-pattern, as it is the first step to get an understanding of reusable gui code. The Observer-pattern is no substitute for the MVC-pattern, but the MVC-pattern implies the Observer-pattern. Any MVC related topic will lead you in a second step to the Observer-pattern (see also The Core Java Technologies Tech Tip of January 13, 2006: http://java.sun.com/developer/JDCTechTips/2006/tt0113.html).
Here are three classes (compiled with Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.2_10-b03)), which demonstrate the Observer-pattern in a very simplified way due to the shortness of code:
The SubjectPanel which notifies the registered ObserverPanel:
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
public class SubjectPanel extends JPanel {
  private JTextField textfield = new JTextField("<Type some text>");
  private ChangeListener listener;
  public SubjectPanel(ChangeListener l) {
    listener = l;
    setLayout(new BorderLayout());
    add(textfield, BorderLayout.CENTER);
    textfield.setSelectionStart(0);
    textfield.setSelectionEnd(textfield.getText().length());
    textfield.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent evt) {
        // notify the listener about the changed text
        listener.stateChanged(new ChangeEvent(textfield));
}The ObserverPanel which wants to be notified when a change in SubjectPanel occures:
import java.awt.BorderLayout;
import javax.swing.BorderFactory;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
public class ObserverPanel extends JPanel implements ChangeListener {
  private JLabel label = new JLabel();
  public ObserverPanel() {
    label.setBorder(BorderFactory.createEtchedBorder());
    setLayout(new BorderLayout());
    add(label, BorderLayout.CENTER);
  // Implementation of ChangeListener. This method is called by SubjectPanel
  // if the text has changed.
  public void stateChanged(ChangeEvent e) {
    label.setText(((JTextField)e.getSource()).getText());
}The main class which contains SubjectPanel and ObserverPanel (Note, that this class doesn't know anything about the communication between the embedded panels):
import java.awt.GridLayout;
import javax.swing.JFrame;
import javax.swing.WindowConstants;
public class AppFrame extends JFrame {
  private SubjectPanel subjectPanel;
  private ObserverPanel observerPanel;
  public AppFrame() {
    setTitle("Observer");
    observerPanel = new ObserverPanel();
    // By passing the ObserverPanel to the SubjectPanel
    // a "one way communication line" is established
    subjectPanel = new SubjectPanel(observerPanel);
    getContentPane().setLayout(new GridLayout());
    getContentPane().add(subjectPanel);
    getContentPane().add(observerPanel);
  public static void main(String[] args) {
    AppFrame frame = new AppFrame();
    frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    frame.pack();
    frame.setVisible(true);
}Please, be aware of the fact, that due to the simplification this example lacks the model which is part of the MVC-pattern. The SubjectPanel represents the Controller and the ObserverPanel the View.