GroupLayout can only be used with one Container at a time

Question

Dear all,
I am a beginner so please don't throw rocks at me...
I have created two frames with NetBeans. One is the main frame (extends from JPanel) and the other frame I put it to be started when pressing a button from the main frame (the second frame extends from JFrame). Both frames are created using the designer in NetBeans, so the code for creating the GUI is automatically generated by NetBeans, so both frames use the same layout (GroupLayout).
Here is the code of the button from the main frame to start the second one:
private void manageCustomersActionPerformed(java.awt.event.ActionEvent evt) {                                                
        // TODO add your handling code here:
        CustomerGUI custGUI1=new CustomerGUI();//CustomerGUI is the second frame
        custGUI1.setVisible(true);
}When I press this button from the main frame I get this runtime exception: Exception in thread "AWT-EventQueue-0" java.lang.IllegalArgumentException: GroupLayout can only be used with one Container at a time. The second frame is not opened.
How should I handle this?
What I want to do: I want to have a main frame, from which I can start additional ones (the main frame must be always opened, while the additional ones can be closed after performing certain actions). I read a little about internal frames and I think this can be a solution, but I must edit the existing design...
Thank you
With respect,
Don
Edited by: don1983p on Dec 16, 2008 2:21 AM

Answer 1

AndrewThompson64 wrote:
There are those that maintain that JFrame should never be extended. I am not convinced, but most cases where a JFrame is extended would be better coded as simply configuring the JFrame within the main(). GUI builders such as found in NetBeans seem to extend JFrame as a matter of course.I too am not rigorous or religious about this either, but try to adhere to this as a matter of practicality and convenience, I find that if I don't extend a JComponent but rather use composition rather than inheritance, it's much easier to use objects of my class when programming in Eclipse. For instance in Eclipse (and in most IDEs), if I type my object name and then a period, it will show all of the method's available for me to use on this object. If I subclass JPanel or JFrame, I'll see a gazillion methods most I don't want to see, and thus most are clutter. On the other hand if I use composition, I'll only see a small number of methods and these will be only the methods that I want to see and need to use.