You probably figured out this
Developer Guide @ wirehark.org[
^]
That would help you quite much. Wireshark is written in C, which would include JNI to access that from a Java implementation.
It might be easier to use a java based network monitor:
JNM[
^]
Your other questions:
2. Yes, you can draw something like that. Also are there libraries that could be helpful:
JFreeChart[
^]
3. the usual way:
- make a rough scratch (idea, used libs, time schedule)
- make detail plans (GUI look, detail functions)
- implementation
- test, test and some more test