Dragging within a JTree

Hi,
I have a JTree and I want to enable the possibility of dragging from one node to another, but I do not want the ability to drag and drop anything external.
I think my problem would be easier to explain in the context of a JTree showing the contents and sub-contents of a directory. I need this JTree to have the ability to drag a file from one sub-directory to another. I also need the ability to drag a certain Sub-Directory and all the files underneath to another location in the JTree. I however do not want dragging anything external like files or text from outside the JTree to in the JTree as they do not make sense in my case.
What is the easiest way to do this? I was looking at [Default DnD Support|http://java.sun.com/docs/books/tutorial/uiswing/dnd/defaultsupport.html] and it seems to say that some support is in place, but I need to write some of the code? I did not understand what I needed to do. I have setDragEnabled(true) to true for the JTree.
Id be grateful to someone who would guide me.
Thanks,
O.O.

Thanks fun_with_me for the links. (I had got the last link, but the first two are new to me.)
While they provide good examples of what needs to be done, I am trying to understand what is the basic amount of code needed to get this to work. The examples out there seem to be from Java 1.3 or 1.4. I am wondering if there are better ways to do this in Java 5 or 6?
As far as the Tutorial in [Default DnD Suppor|http://java.sun.com/docs/books/tutorial/uiswing/dnd/defaultsupport.html] I could not understand the last two paragraphs where they say that the JTree needs some custom code, and that code is fairly minimal.
I hope someone has some ideas
O.O.

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