problems on implementing a JTree

Well I am currently designing a JTree that is dynamicly loaded from a given database.
The way I did it is that I created a class that stores an id, a parent node, a list of child nodes, and the data. Then what I did was creating a list of this class from the original data and did this thing below.

private void writeRTTree()
{
//Change the root node display.
//Initialise the initial nodes.
rtTreeNodes = new DefaultMutableTreeNode[rtNodesFile.nLines];
for(int index = 0; index < rtNodesFile.nLines; index++)
{
//Create a node has the name of it's corresponding report type string.
rtTreeNodes[index] = new DefaultMutableTreeNode(rtNodesFile.rtNodes[index].rtData);
//Insert the node to it's appropriate place.
if(rtNodesFile.rtNodes[index].rtParent == 0)
{
//Adds the node to the root.
rtTreeModel.insertNodeInto(rtTreeNodes[index], rtTreeRoot, rtTreeRoot.getChildCount());
}
else
{
//Adds the node to the corresponding parent.
rtTreeModel.insertNodeInto(rtTreeNodes[index], rtTreeNodes[rtNodesFile.rtNodes[index].rtParent - 1], rtTreeNodes[rtNodesFile.rtNodes[index].rtParent - 1].getChildCount());
}
}
}

The loading was sucessful but when I was trying to locate the user selected node by using "getSelectionPath()", I failed and whan i was trying to print it it returns null pointer exception. However this function works fine before I load the tree.

I sorta knows that my problem is probably because those JTree nodes are created in a tree, but if I dont do that is there any ways I can create those nodes and make them able to respond to user's selection? Or is there any ways I do not need to correct my "writeRTTree()" function and that would be so much better.

Thank You

do i need bumps here or not?

Quote:

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I was trying to locate the user selected node by using "getSelectionPath()", I failed

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Define failed. If you get exceptions or compile time errors, post them here. And it always helps to post an SSCCE that clearly demonstrates the basic premise of what you are attempting to accomplish.