Anyone know a good diagram drawing component for java? I could be a commercial one that is no problem. I have already take a look at JGraph and JGrapht. But I also want to know is there other alternative.

With JGraph I cannot make the TreeAlgorithm work (Auto layout). Also I cannot add my own listener easily to detect a click of something on the drawled object on screen.

Sorry man, I am not familiar with that.  I don't even know what a TreeAlgorithm is....   Hopefully there are other people who can help.

Well TreeAlgorithm will automatically position the graphical parts you supply as a Tree on screen. Also it will check the connections between those object to represent it as best as possible.

For the one who are interested I am using Prefuse atm and this one is really nice and open source