将JCheckBox添加到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