Question

I am creating an editor application, and I am having a problem with my menus. In the object menu, I want to display several objects types using a JTree. These object types are dynamically registered by plugins and follow this style:

trigger.button
trigger.lever
out.door.fallgate
trigger.plate
out.door.door
...

This list of names is unsorted and I want to build a TreeNode structure for a JTree like this:

• trigger
  • button
  • lever
  • plate
• out
  • door
    • fallgate
    • door

Additionally, if the user selects a leaf node, I need to recreate the object name (e.g. trigger.button) from the TreePath. Could someone please advise how this can be done.

Answer 1

In psuedocode, this is what you need to do…

public TreeNode buildTree(){
    String[] names = new String[]; // fill this with the names of your plugins

    TreeNode tree;

    // for each plugin name...
    for (int i=0;i<names.length;i++){
        String currentName = names[i];
        String[] splitName = currentName.split(".");

        // loop over the split name and see if the nodes exist in the tree. If not, create them
        TreeNode parent = tree;
        for (int n=0;n<splitName.length;n++){
            if (parent.hasChild(splitName[n])){
                // the parent node exists, so it doesn't need to be created. Store the node as 'parent' to use in the next loop run
                parent = parent.getChild(splitName[n]);
            }
            else {
                // the node doesn't exist, so create it. Then set it as 'parent' for use by the next loop run
                TreeNode child = new TreeNode(splitName[n]);
                parent.addChild(child);
                parent = child;
            }
        }

return tree;
}

This is only psuedocode – you’ll need to do the work of implementing the TreeNode methods properly, etc. Give it a try yourself – if you have any more problems, create a question and show us that you’ve attempted to do it yourself, then we will be more willing to help you solve the minor problems.