How to extend both MouseAdapter and JPanel??

[Michelle Wang]

Dear friends:
I know java can only extend one class, so looks like I issue an impossible question, but I need to solve this.
I have following code, The JLabels here can be clickable/selectable and deletable, it extends MouseAdapter class and it is a must. but my project needs to extend JPanel, it is also a must, how can I reach this?? I tried to create an inner class to extend MouseAdapter, then to make JLabel clickable/selectable and deletable, like this code. but fails.
can any guru help? or throw some light?

  
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
 
public class MyDeletingLabels extends MouseAdapter {
    JLabel selectedLabel = null;
 
    public void mousePressed(MouseEvent e) {
        Point p = e.getPoint();
        Component[] c = ((JPanel)e.getSource()).getComponents();
        System.out.println("c.length = " + c.length);
        for(int j = 0; j < c.length; j++) {
            if(c[j].getBounds().contains(p)) {
                if(selectedLabel != null && selectedLabel != (JLabel)c[j])
                    selectedLabel.setBorder(BorderFactory.createEtchedBorder());
                selectedLabel = (JLabel)c[j];
                selectedLabel.setBorder(BorderFactory.createLineBorder(Color.red));
                break;
            }
        }
    }
 
    private JPanel getContent() {
        JPanel panel = new JPanel(new GridBagLayout());
        GridBagConstraints gbc = new GridBagConstraints();
        gbc.weightx = 1.0;
        gbc.weighty = 1.0;
        Dimension d = new Dimension(100,25);
        for(int j = 0; j < 4; j++) {
            JLabel label = new JLabel("Label " + (j+1), JLabel.CENTER);
            label.setPreferredSize(d);
            label.setBorder(BorderFactory.createEtchedBorder());
           // gbc.gridwidth = ((j+1) % 2 == 0) ? GridBagConstraints.REMAINDER
           //                                  : GridBagConstraints.RELATIVE;
            panel.add(label);
        }
        panel.addMouseListener(this);
        register(panel);
        return panel;
    }
 
    private void register(JComponent jc) {
        int c = JComponent.WHEN_IN_FOCUSED_WINDOW;
        jc.getInputMap(c).put(KeyStroke.getKeyStroke("DELETE"), "DELETE");
        jc.getActionMap().put("DELETE", deleteAction);
    }
 
    Action deleteAction = new AbstractAction() {
        public void actionPerformed(ActionEvent e) {
            JPanel parent = (JPanel)e.getSource();
            if(selectedLabel != null) {
                parent.remove(selectedLabel);
                selectedLabel = null;
                resetLayout(parent);
            }
        }
    };
 
    private void resetLayout(Container parent) {
        GridBagLayout gridbag = (GridBagLayout)parent.getLayout();
        Component[] c = parent.getComponents();
        for(int j = 0; j < c.length; j++) {
            GridBagConstraints gbc = gridbag.getConstraints(c[j]);
            gbc.gridwidth = ((j+1) % 2 == 0) ? GridBagConstraints.REMAINDER
                                             : GridBagConstraints.RELATIVE;
            gridbag.setConstraints(c[j], gbc);
        }
        parent.validate();
        parent.repaint();
    }
 
    public static void main(String[] args) {
        MyDeletingLabels test = new MyDeletingLabels();
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.getContentPane().add(test.getContent());
        f.setSize(400,400);
        f.setLocation(200,200);
        f.setVisible(true);
    }
}
 
  

Thanks

[Campbell Ritchie]

You need to change two words.
Alter "extends MouseAdapter" to "implements MouseListener."
You will then have to find the remaining 4 methods of MouseListener either from the API documentation, or from the error messages when it won't compile.

Then you can add "extends JPanel" beforee "implements".

Easy

[Ulf Dittmer]

Why is it a must to implement MouseAdapter? How about implementing MouseListener instead, and supplying empty implementations for the methods other than mousePressed?

[Michelle Wang]

Originally posted by Campbell Ritchie:
You need to change two words.
Alter "extends MouseAdapter" to "implements MouseListener."
You will then have to find the remaining 4 methods of MouseListener either from the API documentation, or from the error messages when it won't compile.

Then you can add "extends JPanel" beforee "implements".

Easy

Do you mean
"public class DeletingLabels extends JPanel implements MouseAdapter {..."??

If I didnot remember wrongly, class cannot be imepemented, only extended.
MouseListener is a class, not interface.

If your idea is correct, can you provide runnable code to prove it??
Thanks
[ May 25, 2007: Message edited by: girl sunny ]

[Campbell Ritchie]

Yes. As for runnable code, copy and paste your mousePressed method. Go and find the other four methods from where I told you and implement them with bodies like this

{
   /* empty */
}

[Campbell Ritchie]

I said "implements MouseListener" not "implements MouseAdapter". Go and have a look in the API where I told you and also the Java Tutorial about interfaces.

[Michelle Wang]

Great!! success!! you are really good, I miss your points, my faults.
sorry,very sorry