Implementing a view via a TreeCellRenderer in a JTree

Thread view:

Phil Scholl - 11 Apr 2005 10:47 GMT

Hi!

I have a model of a tree (represented as a JTree) and I want to display
only certain nodes of this tree. My problem is that I want to determine
in the TreeCellRenderer whether this tree node should be displayed.

If I return a null reference in getTreeCellRendererComponent(...) a
NullPointerException is thrown. If I call in the TreeCellRenderer
setVisible(false) on the returned Component, it is displayed nevertheless.

Does anybody know how to accomplish this?

Thanks!
Phil

Reply to this Message

Thomas Weidenfeller - 11 Apr 2005 11:08 GMT

> I have a model of a tree (represented as a JTree) and I want to display
> only certain nodes of this tree. My problem is that I want to determine
> in the TreeCellRenderer whether this tree node should be displayed.

You can't. You need to provide a TreeModel which provides the different
structure of the data. If you check Sun's GUI tutorial, you will find a
similar example for JTables, where in order to create a sorted table,
the original model is wrapped ("decorated") with a sorted model.

You have the same thing to do. Wrap your complete model in some
filtered model - which you have to implement. That filtered model should
provide the desired version of the tree.

/Thomas

Signature

The comp.lang.java.gui FAQ:
ftp://ftp.cs.uu.nl/pub/NEWS.ANSWERS/computer-lang/java/gui/faq

Reply to this Message

Phil Scholl - 11 Apr 2005 11:28 GMT

> You can't. You need to provide a TreeModel which provides the different
> structure of the data. If you check Sun's GUI tutorial, you will find a
[quoted text clipped - 4 lines]
> model - which you have to implement. That filtered model should provide
> the desired version of the tree.

Thanks!
Looks like I have to do that *sigh*
cheers,
phil

Reply to this Message

jonck@vanderkogel.net - 11 Apr 2005 12:17 GMT

The way to do this is by using a technique called "model filtering".
For a good article on this subject, take a look at:
http://www-106.ibm.com/developerworks/java/library/j-filters/

The article uses ListModel to discuss the subject matter, but the idea
is applicable for all models, including TreeModel.

Regards, Jonck

Reply to this Message

Implementing a view via a TreeCellRenderer in a JTree

Free Magazines