Add JCheckBox to JScrollPane

Question

I'm trying to dynamically add check boxes to a scroll pane depending on what is in my db. Currently i have

ResultSet rs = getAvailableUsers();
    try {
        while (rs.next()){
            User temp = new User();
            temp.setUsername(rs.getString("username"));
            temp.setUserNo(rs.getInt("userno"));
            JCheckBox tempCheckBox = new JCheckBox();
            tempCheckBox.setText(temp.getUsername());
            tempCheckBox.setVisible(true);
            checkBoxes.add(tempCheckBox);

        }
    } catch (SQLException ex) {
        Logger.getLogger(SelectProjectTeamGUI.class.getName()).log(Level.SEVERE, null, ex);
    }
    System.out.println(checkBoxes);

    panel.setLayout(new GridLayout(0,1));
    panel.setVisible(true);
    scrollPane.removeAll();
    scrollPane = new JScrollPane(panel);
    for (int i = 0; i < checkBoxes.size(); i++){
        panel.add(checkBoxes.get(i));
        //panel.repaint();
        System.out.println(i);
    }
    scrollPane.setVisible(true);

I can see the outline for the scroll pane but none of the checkboxes are there. All the checkboxes are stored in a vector then pulled back out and added to the panel one at a time. Any ideas why it isn't showing anything? I know the checkboxes are in the vector as i've printed it out and seen them all there.

Thanks for your help in advance.

Answer 1

• there is an logical issue to call panel.removeAll(); instead of scrollPane.removeAll();

• JComponent are added to JViewport not to the JScrollPane

• then to call (after all Items are added to JPanel) panel.revalidate() and panel.repaint() as last code lines in the void

• you have an issue with Concurency in Swing, all updates to already visible Swing GUI must be done on Event Dispatch Thread, but in other hands panel.repaint() notified Event Dispatch Thread and correctly

---

• use JList (non_editable) or JTable (can be editable) with one column (maybe to remove JTableHeader) instead of JPanel with bunch of JCheckBoxes and with un_natural scrolling, note there is stored Boolean value in the model, that representing JCheckBox in the view