JTree node lazy loading + icons problem

Question

Hi all,
I need to build a large tree (10000 nodes). Since this is large to load all at once, i want to load the last level dynamically using the 'treeWillExpand'
Level 1
--Level 2
---Lever 3
----Node loaded dynamically 4.1
----Node loaded dynamically 4.2
----Node loaded dynamically 4.3
What i do is, i load all nodes in level 1,2,3 when application is initially loaded. In the Level 3 node, I add 1 dummy child node. I call it 'Waiting ...'. This I do because I want to display the 'handle' next to Level 3 node. Later on, when i click on the Level 3 'handle', I use this 'treeWillExpand' code:
private void TreeWillExpand(javax.swing.event.TreeExpansionEvent evt) throws javax.swing.tree.ExpandVetoException {
        path = evt.getPath();
        //3 - Level 3
        if (path.getPathCount() == 3) {
            //here I get rid of the 'Waiting ...' node
            computerNode.removeAllChildren();
            //here I add all level 4 nodes
            Iterator it = ArrayList.iterator();
            while (it.hasNext()) {
               .. here i load all Level 4 nodes
Questions:
1.
Is the approach above a good approach, how to load children 'lazilly'?
2.
I also use custom renderer to display different icons for every "tree" level. When I initially expand the 4th level, everything works fine !!! Then I collapse the 4th level and expand it again and here my problem starts:
- my 4th level icon is set to 'root level icon' instead of '4th level' icon. This does not happen, if computerNode.removeAllChildren(); method is removed from listening above
My custom renderer:
class MyTreeRenderer extends DefaultTreeCellRenderer {
    Icon rootIcon;
    Icon siteIcon;
    Icon computerIcon;
    Icon computerUnscannedIcon;
    Icon softwareIcon;
    public MyTreeRenderer(Icon rootIc, Icon siteIc, Icon computerIc, Icon computerUnscannedIc, Icon softwareIc) {
        rootIcon = rootIc;
        siteIcon = siteIc;
        computerIcon = computerIc;
        softwareIcon = softwareIc;
        computerUnscannedIcon = computerUnscannedIc;
    public Component getTreeCellRendererComponent(
            JTree tree,
            Object value,
            boolean sel,
            boolean expanded,
            boolean leaf,
            int row,
            boolean hasFocus) {
        super.getTreeCellRendererComponent(
                tree, value, sel,
                expanded, leaf, row,
                hasFocus);
        //we can draw 4 icon types here
        DefaultMutableTreeNode node = (DefaultMutableTreeNode) value;
        String nodeType = (String) node.getUserObject();
        int level = node.getLevel();
        if (level == 0) {
            setIcon(rootIcon);
        } else if (level == 1) {
            setIcon(siteIcon);
        } else if (level == 2) {
            //make difference between scanned and unscanned computer
            if (node.getDepth() > 0) {
                setIcon(computerIcon);
            } else {
                setIcon(computerUnscannedIcon);
        } else if (level == 3) {
            setIcon(softwareIcon);
        return this;
}Any idea, what am i doing wrong?

Answer 1

durino13 wrote:
1. Is the approach above a good approach, how to load children 'lazilly'?Sounds pretty reasonable to me.
2. I also use custom renderer to display different icons for every "tree" level. When I initially expand the 4th level, everything works fine !!! Then I collapse the 4th level and expand it again and here my problem starts: my 4th level icon is set to 'root level icon' instead of '4th level' icon. This does not happen, if computerNode.removeAllChildren(); method is removed from listening above
Any idea, what am i doing wrong?Ummmm... Load the model the first time (only) the node is expanded... Putz!
And I suggest you listen deeply to Mr Jacobs... He really does know what he's talking about ;-)
... and not this time, but in future: Swing questions are best asked in [THE Swing Forum|http://forums.sun.com/forum.jspa?forumID=57].
Cheers. Keith.