How to refresh XML in Jtree

Question

I read here , but if the xml file changes the jtree does not reload /refreshes
how to create a function for refresh / reload Jtree
I try to write code :

refreshAction = new AbstractAction("Refresh", IconFactory.getIcon("delete", IconFactory.IconSize.SIZE_16X16)) {
public void actionPerformed(ActionEvent e) {
    XMLTree xmlClass = null;
    ((DefaultTreeModel) xmlClass.getModel()).reload(); 
    System.out.println("Refresh");
}};

but i got the error : java.lang.NullPointerException

Answer 1

I added a new Action to popup in getJPopupForExplorerTree(). You'll probably want to re-factor xmlFile out of the XMLTree constructor; I've hard coded it for expedience below:

popup.add(new AbstractAction("Reload") {

    public void actionPerformed(ActionEvent e) {
        System.out.println("Reload");
        try {
            root = getRoot("xml.xml");
            setModel(new XMLTreeModel(root));
        } catch (Exception ex) {
            ex.printStackTrace(System.err);
        }
    }
});

Answer 2

• this is most complex code, probably

• read tutorial about JTables DefaultTableModel (good described concept and logics for DefaultXxxModel is similair / the same)

• read tutorial about JTree

• read tutorial about Concurency in Swing,

• especially description about SwingWorker

• in your case better (sorry for that) would be create an new instance for DefaultTreeModel, fills data by using SwingWorker, add new model to the visible JTree,

• by replacing model you'll lost all changes in the current JTree

Answer 3

I dont know the spesific code but you can try this

refreshAction = new AbstractAction("Refresh", IconFactory.getIcon("delete", IconFactory.IconSize.SIZE_16X16)) {
public void actionPerformed(ActionEvent e) {
     DefaultTreeModel myTreeModel = (DefaultTreeModel) xmlClass.getModel();

     myTreeModel.reload();

     revalidate();
     repaint();
}};