Add panel to a panel

Question

i'm building a Java program. The core of this program is visualized in a JFrame with a JMenuBar and various JMenuItem and JMenu. The point is that I added a centralPanel to all the frame,but if I add something to the centralPanel it shows only if i resize the main frame, reducing it or enlarging it! Here's the code:

This is the constructor:

    public UserFrame(Sistema system)
    {
    Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
    this.setSize(screenSize.width, screenSize.height);
    storicoPanel = new JPanel();
    carrelloPanel = new JPanel();
    carrelloFrame = new JFrame();
    pane = new JScrollPane(storicoArea);
    close = new JButton("Chiudi");
    this.sistema = system;
    menu = new JMenuBar();
    this.setJMenuBar(menu);

    centralPanel = new JPanel();
    add(centralPanel);

Here i added the centralPanel, and here, in an ActionListener, i try to add something to it, but it doesnt' work:

public ActionListener createVisualizzaStorico(final ArrayList<Acquisto> array)
{
    class Visualize implements ActionListener
{
    public void actionPerformed(ActionEvent e)
    {
        storicoPanel.removeAll();
        for(Acquisto a : array)
        {
            Articolo temp = a.getArticolo();
            if(temp instanceof Vacanza)
                storicoPanel.add(new VacanzaPanel((Vacanza)temp));
            else if(temp instanceof BeneDiConsumo)
                storicoPanel.add(new BeneDiConsumoPanel((BeneDiConsumo)temp));
            else if(temp instanceof Cena)
                storicoPanel.add(new CenaPanel((Cena)temp));
            else 
                storicoPanel.add(new PrestazioniOperaPanel((PrestazioneOpera)temp));

        }

        centralPanel.add(storicoPanel);
        centralPanel.repaint();

Could you please help me? Thanks!

Have you attached the action listener? – Kevin Bowersox Feb 04 '14 at 09:50 — Kevin Bowersox, Feb 04 '14 at 09:50
want to replace panel with another panel?? – Java Man Feb 04 '14 at 09:52 — Java Man, Feb 04 '14 at 09:52
Are you using SwingUtilities.invokeLater()? – JavaTechnical Feb 04 '14 at 10:01 — JavaTechnical, Feb 04 '14 at 10:01

score 3 · Accepted Answer · edited May 23 '17 at 10:25

Use a CardLayout instead of trying to add and remove component/panels. It's much cleaner and you don't have to worry about the things that may go wrong, like what you're facing here.

See this example to see how easy and cleaner it is. Also see How to Use CardLayout tutorial

Side Notes

A component can only have one parent container. Though I don't think this is causing a problem for you. It's good to know. First I see you trying to add storicoPanel to a JScrollPane, JScrollPane that you never add to the centerPanel. Then you later add the storicoPanel to the centerPanel. The JScrollPane will no longer be the parent after this.
I'm not sure what you're using this carrelloFrame = new JFrame(); for, but you're class is already a JFrame, why create another?
Just FYI, when adding components dynamically, you need to revalidate() and repaint(). Though, in your situation, I am totally against the adding and removing of components, because this looks like a perfect case for a CardLayout.

Oh my! Thanks a lot, you just saved me! Don't bother about the new frames, I used them to test and to see if it was my fault or JPanel's fault! CardLayout is wonderful, thanks again! — user1868607, Feb 04 '14 at 10:11
For the record, `revalidate()` is what you needed here. It should work calling them both together (as `revalidate()` is required if you're dynamically modifying the component hierarchy). That said, `setVisible(false), repaint(), setVisible(true)` has worked for me historically :) — Gorbles, Feb 04 '14 at 13:56

score 0 · Answer 2 · answered Feb 04 '14 at 10:03

Try these..

centralPanel.updateUI(); // or    
SwingUtilities.updateComponentTreeUI(getRootPane());

Execute your frame code in SwingUtilities.invokeLater()
Instead of repaint() call updateUI() or SwingUtilities.updateComponentTreeUI(getRootPane()) to update the user interface.

Add panel to a panel

2 Answers2