Using nullLayout for custom component

Question

I am writing an AccordianPanel as a custom component that can be dropped into a JPanel and behave as expected. I am using a null layout in the outer container (JPanel) as the accordian dividers need to move as told and not be managed by a layout manager. When I resize a window or another container that the custom component sits in, it doesn't resize anything - I understand this is the behavior I would expect as that is how I coded it.
Now, I want to have the custom component resize its internal stuff when the container it resides in (i.e. JFrame or most likely another JPanel) gets moved, but I don't know how to do this. The outer most component in my custom components hierarchy is a JPanel whose layout is set to null and I stuff everything else inside there.
I believe I need to add a componentListener to my JPanel whose layout is set to null, but I am not sure. Could someone send me in the right direction.
thanks

Answer 1

the best approach might be to implement your own LayoutManager (which is simple enough) and use it rather than absolute positioning....
If you read postings in the forum you will find most people recommend using LayoutManagers and not a null layout so you don't have problems like this.Hello sarcommand , camickr, and anyone interested,
I've tried to bring this discussion up again just a few days ago, and was disappointed I got no feedback - must be a dull read :o(
Here is the [link to the thread|http://forums.sun.com/thread.jspa?messageID=10723670&#10723670], would you mind having an eye on it?
I'm sorry to hijack this thread (seems slightly less rude than bumping my own former thread up), but I've read several discussions on this subject too, and still I can't decide whether I should follow the CustomLayoutmanager track.
Although most of the writing there is specific to my current problem, it highlights 3 points I think are general enough:
- A custom layout (whatever the way it is implemented, I discuss 4 approaches in the thread) is generally used to display custom components, or at least, components that represent custom application-specific entities or input points. -> Is is worth the trouble to abstract the positioning logic when this "custom layout" has only one, at best two, use cases (a couple of specific screens in your specific app that represents your specific entities)?
- A custom (app-specific) layout manager is likely to require more knowledge about the things being layed out than the default min/max/pref sizes. In particular it may require to know data of the underlying model objects represented by the children components. How is that best designed? I tentatively think it's by way of custom Constraint classes which have to be abstract enough yet should be easily mapped from the app-specific data.
- The CustomLayoutManager integrates natively with regular graphical events (hiding, resizing,...), but how to integrate app-specific events (such as, when the underlying data change in such a way that should be reflected by a change in the layout, how/when to force the re-layout)?
Thank you for your help.