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Jtree question

Posted on 2001-09-11
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Last Modified: 2012-06-27
hi, I have a simple question

if I know a node in jtree how do I get
its index.

I have a node  "addnode" which has three
children.

addnode
 --node 1
 --node 2
 --node 3

when the user selects addNode I want
to get the index of all the children of the selected
node.



i.e I want to get index of node 1,node 2,node 3

I can get index of addnode by
 tree.getLeadSelectionRow();

but how do I get indices of the children?

I tried doing this
 Object arr [] = node1.getUserObjectPath();
     TreePath path = new TreePath(arr);
     int index = dragTree.getRowForPath(path);

but I always get index as -1


Thanks

0
Comment
Question by:sanjay_thakur
  • 5
  • 2
  • 2
  • +1
10 Comments
 
LVL 9

Expert Comment

by:Ovi
Comment Utility
I didn't understand exactly what you want. For what do you need the indexes and not the childs ?
0
 

Accepted Solution

by:
lawpan earned 25 total points
Comment Utility
DefaultMutableTreeNode destination = null;
for (int i = 0;i<destination.getChildCount();i++)
{
  int index = destination.getIndex(destination.getChildAt (i));
 System.out.println(index);
}
0
 

Expert Comment

by:lawpan
Comment Utility
Notice that destination is null.
Replace this with your node.
Beside, if you have 3 children, you always know that indeces are 0,1,2. Or do you want indeces against the whole tree?
0
 

Expert Comment

by:lawpan
Comment Utility
If you want the indeces relative to the whole tree,
for (int i = 0;i<destination.getChildCount();i++)
{
    TreePath t = new TreePath(((DefaultMutableTreeNode)destination.getChildAt(i)).getPath());
    int index = getRowForPath(t);
    System.out.println(index);
}

You have to typecast the TreeNode to defaultMutableTreeNode
(correction due your example) to get the TreePath
0
 
LVL 4

Author Comment

by:sanjay_thakur
Comment Utility
Hi,

I tried your solution.
There is a weird problem

If the parent node is not expanded I get the
indices of the child nodes as -1

but If I expand the parent node and then try doing the same
I get the proper values.

I can write code to dynamically expand the
node but I want to know if
this is normal or there is something I am missing

This is the code snippet

selNode = dragTree.                            getLeadSelectionPath().getLastPathComponent();



        System.out.println("selNode " + selNode);
     indexArray = new int[nodeList.size()];

     for (int i = 0;i<selNode.getChildCount();i++)
        {
        TreePath t = new TreePath(((DefaultMutableTreeNode)selNode.getChildAt(i)).getPath());
        System.out.println("t" + t);
        int index = dragTree.getRowForPath(t);
        System.out.println("index" + index);
        indexArray[i] = index;
        }









0
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LVL 92

Expert Comment

by:objects
Comment Utility
> int index = dragTree.getRowForPath(path);

That's not the indice of the the node, that's the displayed row number.
The indices of the child nodes are 0, 1, 2.
0
 

Expert Comment

by:lawpan
Comment Utility
Yes. You got -1 because
if you tree is
-Node (expanded)
--Child
--Child
-Node2 (collpased with 2 childs also)
-Node3 (empty)

If you are asking the index of child1 of node2 that is NOT visible in tree.(int index = dragTree.getRowForPath(t);
)
You have got -1 since there is no rowForThatPath.

Maximal index in the tree that may be returned is 4 in the example.(0,1,2,3,4 = 5 visible nodes)
And you need to know the index of a node that is not visible.
If you expand node2 then indeces are rearranged. Node index 4(that is child1 of node2) is pointing to a different node in the tree. This means that knowning indeces relativ to the tree dont give you any specific information since the indeces of nodes are changed and repointed to different nodes.
Could you tell my why do you need those indeces. I may understand you problem better and give another soution.
0
 
LVL 4

Author Comment

by:sanjay_thakur
Comment Utility
okk

I have a node like this

--switch
   --disk 0
   --disk 1
   --disk 2

now there are different volumes associated with these
children
say the disk0--volume 30 gb
        disk1--volume 50 gb
        disk2--volume 60 gb


when the user drags this switch node and drops it
under a drop target node say "target" I want to
add these childern to the "target"
like this
--target
   --disk0--30
   --disk1--50
   --disk2--60


I assumed that indices and row number means the same
but what I need is row numbers of the children
since I read these volumes from an array based on the
row number

ex:row number 2 --volume associated is array[2];

so when a user selects switch and drags it; I need
to know the row numbers of all the children so that
I can accordingly read the volumes from the array

That's the reason I need to know the row numbers
even if the children are not visible


Is it that If I dont expand the node I wont be able to get the row numbers of the children?

I have dynamically expanded the selected node
and it works ok

Just ket me know if there is a better solution to this?









 







0
 

Expert Comment

by:lawpan
Comment Utility
Hmm
DnD
You have the target, you have the source and its children.
If you setUserObject that is a volume added in disk.
You easy get the userObject from source and add to the target.
I have hard to believe that you need indeces att all.
Only when traversing the parent from source and its easy, as from my very first example. Dont use rowforpaTH.
0
 
LVL 92

Expert Comment

by:objects
Comment Utility
DefaultMutableTreeNode destination = ...;
for (int i = 0;i<destination.getChildCount();i++)
{
   int index = i;
   System.out.println(index);
}


:-)
0

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