Error in coding in Eclipse SDK

Question

I'm getting the following error:
The method setFirewall(Firewall) in the type InternetQuery is not applicable for the arguments (Firewall)
It also happens in these other instances:
The method setInteraction(Interaction2D) in the type Draw2D is not applicable for the arguments (Interaction2D)
Even weirder is there are two copies of this class (Not my code) yet the other identical class doesn't have this problem. The only difference is the package, but dragging one into the other's package doesn't change anything.
My confusion results from me sending the exact object to the method that it's supposed to take as a parameter, yet Eclipse doesn't seem to realize that. I've tried running it through javac as well to see if that helps (I'm on a redhat linux VPM), but that didn't work either.
Any ideas on what to do?
I've tried casting the inputs to see if that would help, and no luck. I also tried Eclipse's recommended fixes, but those created other problems. If you know how to use Eclipse's recommended fixes that could help as well. Thanks in advance for any responses.

Answer 1

This sounds like a very simple problem, made more
difficult by a large number of classes. I'm not sure
that it's something that can really be solved on a
discussion forum, due to the large number of classes.
However, here are some things to think about:
1) Start by understanding your package structure. I
don't know if you're using 3rd-party code from a jar,
or if you've written everything. In the former case,
use "jar tvf" to get a listing of the contents of the
JAR. In the latter, use "find" (on Linux, probably
the search command on Windows) to get a listing of
all your .java file.
Correct, the code is 3rd party. I'll do that once I get the chance, which should be shortly. I can see all the classes as is in the project workspace though.
2) If you're using default packages anywhere (no
"package" statement at the top of the java file),
don't. Put all your code into packages.
I'll check, but I'm pretty sure there isn't. Eclipse shows the default package in the hierarchy, and that's not listed, so it would follow that it doesn't exist. I'll check anyways though.
3) Look at the files that are having problems, and
make sure that you import the proper classes (based
on the inheritance hierarchy in your project).
I'll check about importing the proper files as well.
If all of those are not the case though, is there anything else you could think of that it would be?
Part of the problem with this as well is thatwhile
importing the classes from other packages allowthe
class to be compiled in Eclipse, compiling them ina
terminal using the javac command doesn't work, asit
can't recognize the packages.It sounds like you haven't set up your compile-time
classpath. If you have classfiles in different
directory trees (or JARs) you'll need to specify the
-classpath option to javac. You'll also need to
compile the classes in the order of their
dependencies.
Okay, I'll toy around with that. That would make sense, as each package as its own directory.
As a side note, in the future it will help if you
paste the exact error message, along with the code
that it refers to.
Will do.