Java Custom Tree Model updating problem

Question

Here is structure of the tree:

root -branches --leafs

I use for TreeModel DefaultTreeModel and my objects implement TreeNode interface

leaf is some Object:

public class Leaf implements TreeNode
{
   // implementation

branch has List of leafs:

public class Branch implements TreeNode
{
 private List<Leaf> leafs;

 // implementation

And root is container of branches:

public class Root implements TreeNode
{
  private List<Branch> branches;

  // implementation

When I add new leaf, my tree doesn't updated, when I add leaf and create new DefaultTreeModel with my root object it's updated. I watch DefaultMutableTreeNode implementation, there isn't any event firing on inserting childs... What am I doing wrong? Before, I tried to implement TreeModel interface wich looks much better then implementing TreeNode interface for three classes, but result was similar. I also read about GlazedLists, but I dislike their tree conception. For me, the best is implementation TreeModel interface conception, but how to update model when some inner List in model add new element?...

there is great method DefaultTreeModel.reload(TreeNode node) :) it solve problem. — Artyom Chernetsov, Sep 23 '11 at 07:54
no, that doesn't solve the error in your code - it only hacks around it. — kleopatra, Sep 23 '11 at 08:00
So, TreeNode implementations are wrong? They must fire some events? — Artyom Chernetsov, Sep 23 '11 at 08:02
no, typically nodes dont fire (they dont know enough) - the code which does the modification must notify the model. — kleopatra, Sep 23 '11 at 08:11

kleopatra · Accepted Answer · 2011-09-23T08:09:34.930

4

Without seeing the code, it's hard to be sure - nevertheless I'll bet on my guess: you don't notify the TreeModel about your insertions ;-)

A code snippet of what you have to do if your node implementation is not of type MutableTreeNode:

 // do the parent wiring in your custom TreeNode
 int position = myBranch.addChild(node);
 // notify the model 
 model.nodesWhereInserted(myBranch, new int[] {pos});

If it is of type MutableTreeNode, the easier way is via the convenience methods in DefaultTreeModel

 model.insertNodeInto(node, myBranch, position)

edited Sep 23 '11 at 08:09

answered Sep 23 '11 at 08:01

kleopatra

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thanks, it's what I looking for, now I found how it's implemented in DefaultTreeModel – Artyom Chernetsov Sep 23 '11 at 08:14

score 2 · Answer 2 · edited May 23 '14 at 23:57

2

that look like as issue with Concurrency in Swing, maybe updates are out of EDT,

you have add new Object, then to test DefaultTreeModel if contains new Object, if Objects exists, then you have to wrap (all updates) into invokeLater, for Serializable or Observate would be better look for invokeAndWait

edited May 23 '14 at 23:57

BenMorel

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answered Sep 23 '11 at 08:07

mKorbel

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bet that's not the issue here :-) – kleopatra Sep 23 '11 at 08:12
somebody has (and we talking about Friday) still unbelievable magic globe, lady, lady my +1 – mKorbel Sep 23 '11 at 08:24

Java Custom Tree Model updating problem

2 Answers2