Extends JScrollPane

Question

Hi everyone,
I am trying to extend JScrollPane component and show a tree component
into the extended
JScrollPane. I can compile the code, but when the JScrollPane is showed it is empty. This is the code that I am using:
class JScrollPaneObjectInspector extends JScrollPane {
      private JTree tree = null;
    public JScrollPaneObjectInspector()
        super();
        setSize(200, 200);
      //Inspect this object
        PointTest testClass = new PointTest(1,1);
        Class clsInfo = testClass.getClass();
        Variable v = new Variable(clsInfo, clsInfo.getName(), PointTest.class);
      ObjectTreeModel model = new ObjectTreeModel();
      model.setRoot(v);
      // construct and show tree
      setTree(new JTree(model));
      super.add(getTree());
    public void setTree(JTree tree) {
        this.tree = tree;
    public JTree getTree() {
        return tree;
public class MainWindow {
    private JFrame jFrame = null;...
     * This method initializes jSplitPane
     * @return javax.swing.JSplitPane
    private JSplitPane getJSplitPane() {
        if (jSplitPane == null) {
            jSplitPane = new JSplitPane();
            jSplitPane.setRightComponent(getJScrollPaneRight());
        return jSplitPane;
     * This method initializes jScrollPaneLeft
     * @return javax.swing.JScrollPane
    private JScrollPane getJScrollPaneRight() {
        if (rightSPaneObjInspector == null)
            rightSPaneObjInspector = new JScrollPaneObjectInspector();
            rightSPaneObjInspector.setPreferredSize(new Dimension(200, 200));
        return rightSPaneObjInspector;
     * @param args
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                MainWindow application = new MainWindow();
                application.getJFrame().setVisible(true);
}In the code I don't show how I create the tree, but this part is working, because I have test this with JScrollPane component directly. Thank very much for any help

Answer 1

There is no need to extend a scrollpane simply because you want to add a component to it. That is not new functionality as the scroll pane is designed to display components. Your basic code should be:
JTree tree = new JTree(...);
JScrollPane scrollPane = new JScrollPane( tree );I would guess the main problem with you code is that you don't "add" components to a scrollpane. Components are added to the viewport of the scrollpane. The easiest way to do this is when you create the scrollpane as I showed above. Otherwise you can set the viewport directly:
scrollPane.setViewportView( tree );