My problem is that I am not able see a new Internal frame when I click the 'Show Frame 2' button in one internal frame.
The code for the files is as follows.Also the code for internal frames has to be in separate files.
What changes are needed to fix the problem?
You never add the new InFrame2 instance to any JDesktopPane. You'll need to give InFrame1 a field of type JDesktopPane, set in its constructor, that it then uses. A quick-and-dirty version (all classes are made non-public so they can fit in one file; look for lines with "// change here"):