Why do I get multiple class files from 1 java file?

Question

I wrote a dialog box using gridBagConstraints and another program RunPanel to run it as a java application. For the first time since playing with java, I get multiple class files from a single java file.
This seems very strange to me and wonder if anyone else has come across this and what could possibly be the reason for it. I did a clean (in Eclipse) just to make sure it wasn't garbage and sure enough they come back again.
I have ReconPanel.java from which I get ReconPanel.class with the addition of ReconPanel$N.class where N goes from 1 to 5.
The same thing in RunPanel but here there is only 1 extra file, RunPanel$1.class.
I'll include the code for RunPanel since it is relatively small:
package ilan;
import javax.swing.JFrame;
public class RunPanel extends JFrame {
     private static final long serialVersionUID = 1L;
     private ReconPanel m_reconPanel = null;
     public RunPanel() {
          super();
          initialize();
      * This method initializes this
     private void initialize() {
        this.setTitle("tester");
        this.setSize(new java.awt.Dimension(138,396));
        this.addWindowListener(new java.awt.event.WindowAdapter() {
             public void windowClosing(java.awt.event.WindowEvent e) {
                  m_reconPanel.exitPanel();
                  System.exit(0);
          m_reconPanel = new ReconPanel();
          this.getContentPane().add(m_reconPanel);
      * @param args
     public static void main(String[] args) {
          JFrame frame1 = new RunPanel();
          frame1.setVisible(true);
}  //  @jve:decl-index=0:visual-constraint="10,10"The only thing "unusual" I do is to put a listener on the WindowClosing so that I can go back to ReconPanel and write results to the registry.
Can anyone tell me what is going on?
Thanks,
Ilan

Answer 1

He IIan,
Yes, you get number of extra class files based on your number of anomyous class es used. Like in your RunPanel, you get only 1 ..$1.class file, b'coz u have used only 1 annomyous class & i.e WindowAdapter. Take a look at this code :-
this.addWindowListener(new java.awt.event.WindowAdapter() {
             public void windowClosing(java.awt.event.WindowEvent e) {
                  m_reconPanel.exitPanel();
                  System.exit(0);
        });Similarly, in your ReconPanel, you must have used such kind of classes 5 times, & hence u get such 5 extra classes. To avoiod such extra classes, if you can directly implement that interface or extend the class, if possible will be best. For example, for each button, u write
button1.addActionListener(new ActionListener() {
// Code
});Instead, of this, its better to implement ActionListener & write
button1.addActionListener(this);
public void actionPerformed(ActionEvent ae) {
   if (ae.getSource() == button1) {
   // CODE
   }Likethis, you can get rid of such numerous extra class files. In IDE, if you ask to add actionEvent, it will do the first method. To get rid of it, don't add event in the properties, instead, apply the second method. The same thing applies for anyother event. The first option is worthful, if by implementing, u got to write 5 functions from which u r gonna use just 1 method.
Hope this clears your question.
Trupti