Hi Chanchal,

The  simplest solution is to enhance the DefaultTreeSelectionModel
class (Java 6 listing below):

public class RestrictedTreeSelectionModel extends
DefaultTreeSelectionModel {
   private static final long serialVersionUID =
-4055323556188518616L;
   @Override
   public void setSelectionPaths(final TreePath[] pPaths) {
       final ArrayList<TreePath> temp = new ArrayList<TreePath>();
       for (int i = 0, n = pPaths != null ? pPaths.length : 0; i < n;
i++) {
           final Object lastPathComponent =
pPaths[i].getLastPathComponent();
           if (lastPathComponent instanceof TreeNode) {
               if (((TreeNode) lastPathComponent).isLeaf()) {
                   temp.add(pPaths[i]);
               }
           }
       }
       if (!temp.isEmpty()) {
           super.setSelectionPaths(temp.toArray(new
TreePath[temp.size()]));
       }
   }
}

This solution has one negative effect:
if the selection mode is CONTIGUOUS_TREE_SELECTION,
only children of the same parent can be selected.

BR, Alex