Arranging Nodes in A JTree
java, jtree, sorting, swing
Solution
I think both are fine solutions. It was pretty easy to tell what they were doing: pull out the files, pull out the folders, throw them back in the tree in the right order. Also, the recursive call was straight-forward and intuitive.
Pick whichever seems the most natural to you. The second seems more like the way I would do it, but that's just me, and there's not much difference.
Are you using Java 5 or 6? If so, use for-each loops. Also, you don't have to clear that values of your private variables at the end of the method. They go away anyhow when the method returns.
Problem
I have a JTree in which the user can drag/drop or re-arrange nodes, upon saving I have to re-arrange the nodes such that File type nodes must appear before Folder type nodes. I don't need to sort the files/folders name. User Tree: ``` -FolderA +FFA1 -FA1 -FA2 -FolderB -FB1 -File1 -File2 +FolderC -File3 ``` Resulting Tree: ``` -File1 -File2 -File3 -FolderA -FA1 -FA2 +FAF1 -FolderB -FB1 +FolderC ``` I have the following codes below, it worked but I don't know if it is the proper way or the good practice perhaps. Can you suggest which of the 2 solutions is better, or can you suggest other way. Thanks you very much. Solution 1: ``` private void arrange(DefaultMutableTreeNode parent){ DefaultMutableTreeNode sorted = new DefaultMutableTreeNode(); List<DefaultMutableTreeNode> files = new ArrayList<DefaultMutableTreeNode>(); List<DefaultMutableTreeNode> folders = new ArrayList<DefaultMutableTreeNode>(); for (int i = 0; i < parent.getChildCount(); i++){ DefaultMutableTreeNode node = (DefaultMutableTreeNode) parent.getChildAt(i); int type = ((BusinessObject) node.getUserObject()).getType(); if (type == BusinessObject.FILE) files.add(node); else{ arrange(node); folders.add(node); } } for (int i = 0; i < files.size(); i++) sorted.add((DefaultMutableTreeNode) files.get(i)); for (int i = 0; i < folders.size(); i++) sorted.add((DefaultMutableTreeNode) folders.get(i)); while (sorted.getChildCount() > 0) parent.add((DefaultMutableTreeNode) sorted.getChildAt(0)); sorted = null; files = null; folders = null; } ``` Solution 2: ``` private void arrange(DefaultMutableTreeNode parent){ DefaultMutableTreeNode sorted = new DefaultMutableTreeNode(); List<DefaultMutableTreeNode> nodes = new ArrayList<DefaultMutableTreeNode>(); for (int i = 0; i < parent.getChildCount(); i++){ DefaultMutableTreeNode node = (DefaultMutableTreeNode) parent.getChildAt(i); int type = ((BusinessObject) node.getUserObject()).getType(); if (type == BusinessObject.FILE) nodes.add(node); } for (int i = 0; i < parent.getChildCount(); i++){ DefaultMutableTreeNode node = (DefaultMutableTreeNode) parent.getChildAt(i); int type = ((BusinessObject) node.getUserObject()).getType(); if (type == BusinessObject.FOLDER){ arrange(node); nodes.add(node); } } for (int i = 0; i < nodes.size(); i++) sorted.add((DefaultMutableTreeNode) nodes.get(i)); while (sorted.getChildCount() > 0) parent.add((DefaultMutableTreeNode) sorted.getChildAt(0)); sorted = null; nodes = null; } ```