Question

I would like to create an index (1, 1.2, 1.3, 2.1 etc.) for each node of a JTree at the time of adding the new node,

i.e.

root
|
 ---1 node
|
 ---2 node
    |
     ---2.1 node 

Does anybody have an idea how I can do it? Thank you in advance for any answers.

Answer 1

Since you didn’t tell us, if you have implemented your own TableModel, I assume, that you work with a standard JTree and the default model. A method that retrieves the index of a Node as a String would look like this:

public String getNodeIndex(JTree tree, TreeNode node) {
    TreeNode root = (TreeNode) tree.getModel().getRoot();
    if (node == root) {
        return "";
    }
    TreeNode parent = node.getParent();
    if (parent == null) {
        return null;
    }
    String parentIndex= getNodeIndex(tree, parent);
    if (parentIndex == null) {
        return null;
    }
    return parentIndex+"."+parent.getIndex(node);
}

This code should work as long as you don’t build cycles into your tree, as if works recursively up to the root.