Example Depot

tree.addTreeSelectionListener(new TreeSelectionListener() {
    public void valueChanged(TreeSelectionEvent evt) {
        // Get all nodes whose selection status has changed
        TreePath[] paths = evt.getPaths();

        // Iterate through all affected nodes
        for (int i=0; i<paths.length; i++) {
            if (evt.isAddedPath(i)) {
                // This node has been selected
            } else {
                // This node has been deselected
            }
        }
    }
});