Problem with JTable and JPanel

Question

Hi,
I'm having problems with a JTable in a JPanel. The code is basicly as follows:
public class mainFrame extends JFrame
        public mainFrame()
                //A menu is implemeted giving rise to the following actions:
                public void actionPerformed(ActionEvent evt)
                        String arg = evt.getActionCommand();
                        if(arg.equals("Sit1"))
                        //cells, columnNames are initiated correctly
                        JTable table = new JTable(cells,columnNames);
                        JPanel holdingPanel = new JPanel();
                        holdingPanel.setLayout( new BorderLayout() );
                        JScrollPane scrollPane = new JScrollPane(holdingPanel);
                        holdingPanel.setBackground(Color.white);
                        holdingPanel.add(table,BorderLayout.CENTER);
                        add(scrollPane, "Center");
                        if(arg.equals("Sit2"))
                                if(scrollPane !=null)
                                        remove(scrollPane);validate();System.out.println("ScrollPane");
                                if(holdingPanel !=null)
                                        remove(holdingPanel);
                                if(table !=null)
                                        remove(table);table.setVisible(false);System.out.println("table");
                        //Put other things on the holdingPanel....
        private JScrollPane scrollPane;
        private JPanel holdingPanel;
        private JTable table;
}The problem is that the table isn't removed. When you choose another situation ( say Sit2), at first the table apparently is gone, but when you press with the mouse in the area it appeared earlier, it appears again. How do I succesfully remove the table from the panel? Removing the panel doesn't seem to be enough. Help is much appreciated...
Best regards
Schwartz

Answer 1

If you reuse the panel and scroll pane throughout the application,
instantiate them in the constructor, not in an often-called event
handler. In the event handler, you only do add/remove of the table
on to the panel. You can't remove the table from the container
which does not directly contain it.
if (arg.equals("Sit2")){
  holdingPanel.remove(table);
  holdingPanel.revalidate();
  holdingPanel.repaint(); //sometimes necessary
}