Question

I have VTreePanel class that extends from CPanel which extends from JPanel. The class has a JSplitPane object that is divided into two area: left & right. The left side contains tree menu selection object. At right side, it contains JTabbedPane object. The VTreePanel class is like this:

public final class VTreePanel extends CPanel
    implements ActionListener
{
    private JSplitPane centerSplitPane = new JSplitPane();

    private JTabbedPane tabbedPane;

    ...

    // GET method for the tabbedPane    
    public JTabbedPane getTabbedPane() {
        return tabbedPane;
    }

    // Constructor
    public VTreePanel(int WindowNo, boolean hasBar, boolean editable)
    {

        ...

        tabbedPane = new JTabbedPane();
        centerSplitPane.add(treePart, JSplitPane.LEFT);
        centerSplitPane.add(tabbedPane, JSplitPane.RIGHT);  // Look at this

        ...
    }

}

In constructor, I added the tree selection (treePart) and JTabbedPane object (tabbedPane) into the JSplitPane object (centerSplitPane). I don’t add any Tab into the tabbedPane yet. Look at the screenshot below:

http://i45.tinypic.com/2v3j0nl.jpg

Then how do I add the tab when user click one of the menu?

I have AMenu class where it has implemented PropertyChangeListener that fired propertyChange method when user clicked a menu:

public final class AMenu extends CFrame
    implements ActionListener, PropertyChangeListener, ChangeListener
{

    private VTreePanel treePanel = null;    // this is the VTreePanel object

    ...

    public void propertyChange(PropertyChangeEvent e)
    {
        ...

        // Here I pass the VTreePanel object as parameter to AMenuStartItem thread object
        (new AMenuStartItem(cmd, true, sta, this, treePanel)).start();
    }

}

You can see that I have VTreePanel object (treePanel) and I pass the VTreePanel object as parameter to AMenuStartItem thread. The AMenuStartItem contains logic that perform adding Tab in JTabbedPane (remember, JTabbedPane object (tabbedPane) is in the VTreePanel).

Here is the AMenuStartItem thread class:

public class AMenuStartItem extends Thread implements ActionListener
{
    private VTreePanel m_vtreePanel;

    public AMenuStartItem (int ID, boolean isMenu, String name, AMenu menu, VTreePanel vtreepanel)
    {
        ...

        m_vtreePanel = vtreepanel;  // save the VTreePanel object
    }

    // The thread method that executed when thread is started
    public void run()
    {
        ...

        startWindow(0, cmd);

        ...
    }

    private void startWindow(int AD_Workbench_ID, int AD_Window_ID)
    {
        ...

        // Here I perform adding new tab
        m_vtreePanel.getTabbedPane().addTab(frame.getTitle(), frame.getAPanel());

        ...
    }

}

So, the getTabbedPane() returned the JTabbedPane object and the addTab() method is executed but no tab showed up at all.

Anyone know how to fix this problem?

Answer 1

All interactions with the UI MUST be done via the Event Dispatching Thread, no exceptions…

public class AMenuStartItem extends Thread implements ActionListener
{
    private VTreePanel m_vtreePanel;

    public AMenuStartItem (int ID, boolean isMenu, String name, AMenu menu, VTreePanel vtreepanel)
    {
        ...

        m_vtreePanel = vtreepanel;  // save the VTreePanel object
    }

    // The thread method that executed when thread is started
    public void run()
    {
        ...

        startWindow(0, cmd);

        ...
    }

    private void startWindow(final int AD_Workbench_ID, final int AD_Window_ID)
    {
        ...

        if (EventQueue.isDispatchingThread()) {
            // This is safe, we're in the EDT
            m_vtreePanel.getTabbedPane().addTab(frame.getTitle(), frame.getAPanel());
            m_vtreePanel.getTabbedPane().invalidate();
            m_vtreePanel.getTabbedPane().repaint();
        } else {
            // This is unsafe, we need to resync with the EDT
            SwingUtilities.invokeLater(new Runnable() {
                public void run() {
                    // Here I perform adding new tab
                    m_vtreePanel.getTabbedPane().addTab(frame.getTitle(), frame.getAPanel());
                    m_vtreePanel.getTabbedPane().invalidate();
                    m_vtreePanel.getTabbedPane().repaint();

                }
            });
        }

        ...
    }

}