 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
Java Forum / GUI / October 2004JTree: Catching the setUserObject() call in a DefaultMutableTreeNode
I am trying to debug a JTree. Specifically a particular DefaultMutableTreeNode is having its userObject property set to null. What is the easiest way that I can catch the set occuring? In the case in question I want the root DefaultMutableTreeNode to always contain the userObject "Values". Somewhere in the code "Values" is being replaced by null. How do I find out where this is? (Same question!). I know how to replace the Swing version of DefaultMutableTreeNode with one I have written, so that I can debug this action for every single DefaultMutableTreeNode in every JTree. But really I am hoping that there is some quite obvious way, using the JTree API, that I have overlooked. thanks - Chris Murphy > I am trying to debug a JTree. Specifically a particular > DefaultMutableTreeNode is having its userObject property set to null. > What is the easiest way that I can catch the set occuring? 1. Hard way: examine every node in the tree. When you encounter a null, you stop. 2. Less hard: trap all assignments to the node in question and examine them. To trap them, override the assignment method in a class derived from DefaultMutableTreeNode. > I know how to replace the Swing version of DefaultMutableTreeNode with > one I have written, so that I can debug this action for every single > DefaultMutableTreeNode in every JTree. But really I am hoping that > there is some quite obvious way, using the JTree API, that I have > overlooked. That is how you do it -- derive your own class.  SignaturePaul Lutus http://www.arachnoid.com > 1. Hard way: examine every node in the tree. When you encounter a null, you > stop. Fair enough, but I need the event at which time this happens, or some type of method overriding, or replacement ... > 2. Less hard: trap all assignments to the node in question and examine them. > To trap them, override the assignment method in a class derived from [quoted text clipped - 7 lines] > > That is how you do it -- derive your own class. I actually meant replace rather than override, using a bootclasspath -X option when running Java. You just get Sun's source code and alter it to output debugging messages. However I tried this and peeked into (ie. wrote debugging lines in) the method DefaultMutableTreeNode.setUserObject(). The problem was that the userObject property seems to be being set some other way. Will get back to here when I find the way to do this, or work out my silly mistake! - Chris Murphy / ... >> That is how you do it -- derive your own class. > > I actually meant replace rather than override, using a bootclasspath > -X option when running Java. With only the slighest exaggeration I can say the entire point of object-oriented programming is to be able to modify an existing class by extending it and overriding selected methods. That way you don't have to try to hack the original class source file. In modern times, the latter is unbelievably primitive, as well as unnecessary. > You just get Sun's source code and alter > it to output debugging messages. Sounds simple. But it is a VBI(tm). > However I tried this and peeked into (ie. wrote debugging lines in) > the method DefaultMutableTreeNode.setUserObject(). The problem was > that the userObject property seems to be being set some other way. > Will get back to here when I find the way to do this, or work out my > silly mistake! Reconsider your entire approach. SignaturePaul Lutus http://www.arachnoid.com Hi Paul, I was talking about debugging something, not the design of the code. The replacement of Sun's code is only a temporary measure to find something out. I'm actually right into OO programming, although I seldom use inheritance. > silly mistake! This thread continued here, where a brute force method/s of debugging employed: http://groups.google.com/groups?hl=en&lr=&threadm=5107bf74.0410081552.756543e1%4 0posting.google.com&rnum=1&prev=/groups%3Fhl%3Den%26lr%3D%26q%3DChris%2BMurphy%2 6btnG%3DSearch%26meta%3Dgroup%253Dcomp.lang.java.gui - Chris Murphy > I am trying to debug a JTree. Specifically a particular > DefaultMutableTreeNode is having its userObject property set to null. > What is the easiest way that I can catch the set occuring? The only visible occurance of setUserObject in the standard classes is in DefaultTreeModel.valueForPathChanged. Try overriding it. Christian Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
|
Reply to this Message
|
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2008 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.