Eclipse - plugin to find unused CLASS MEMBER VARIABLES?

[steve.chambers]

I've recently been looking for some tools to help partly automate a
pretty labourious process of doing a big batch of code reviews. Very
happy with the ones I've found so far (PMD, CheckStyle and an obscure
plugin to find unused classes at http://seessle.de/dclj/de.seessle.
eclipse tools.zip ). Would recommend them to anyone!

But there's one thing that none of them seem to do - find public or
protected class member variables that aren't used within the whole
project. (The nearest to donig this is that PMD will find variables
that are declared within a particular class but not used in it - but
this isn't quite what I want as there seem to be quite a few constants
that aren't referenced anywhere within the project).

Does anyone know if such a tool exists, ideally for eclipse but if none
exists then I'd consider using a non-eclipse based one...

Thanks for any help / suggestions....

Cheers,
Steve

 

[Chris Uppal]

But there's one thing that none of them seem to do - find public or
protected class member variables that aren't used within the whole
project. (The nearest to donig this is that PMD will find variables
that are declared within a particular class but not used in it - but
this isn't quite what I want as there seem to be quite a few constants
that aren't referenced anywhere within the project).

I don't know of any such tool personally, but try looking for whole-program
optimisers, which often detect such cases. You may or may not be able to
persuade one to list the stuff it removes. Also check out obfuscators which
(AFAIK) quite often do the same kinds of optimisation.

Or I could write one for you if you liked, but it'd co$$$t you ;-)

BTW, you won't be able to find unused constants (by which I take it you mean
static final int/bool/String fields initialised to constant values), since uses
of such fields are inlined by the compiler and so would all show up as "unused"
by any byte-code-level analyser. You may be able to find a source-level
analyser that would do the job, but I wouldn't say much for your chances of
finding one that works well since source-level analysis is /much/ harder than
bytecode level (especially since Java5). Probably the easiest thing is just
to comment-out any suspicious constant and see if the build breaks...

-- chris

 

[steve.chambers]

Cheers for the quick reply Chris. Will have a look for an obfuscator.
As for writing one, unfortunately I'm a lowly programmer in this
company and am pretty sure I wouldn't be able to convince them to spend
anything (they're trying to use free stuff where possible, hence the
tools I've mentioned . Maybe my best bet is manually go through them
all using Eclipse's references finder on each constant to find out
whether it's used or not in the project or workspace.

Best regards,
Steve

 

[Rhino]

Cheers for the quick reply Chris. Will have a look for an obfuscator.
As for writing one, unfortunately I'm a lowly programmer in this
company and am pretty sure I wouldn't be able to convince them to spend
anything (they're trying to use free stuff where possible, hence the
tools I've mentioned . Maybe my best bet is manually go through them
all using Eclipse's references finder on each constant to find out
whether it's used or not in the project or workspace.

Actually, Chris's approach may be faster: just comment out every variable
you're not sure is being used and then see if the code will compile. Then
uncomment everything that raises an error message. When you finally get a
clean compile, you know you've got all the variables that are being used.
Then, go through your source and delete all those commented variables.

This is still likely to be a time-consuming process if you have many classes
and many suspect variables but it may still be cheaper than writing
something which does the same thing. Or not.

Rhino

 

[Roedy Green]

Maybe my best bet is manually go through them
all using Eclipse's references finder on each constant to find out
whether it's used or not in the project or workspace.

Another approach would work this.

You use a class file library (see
http://mindprod.com/jgloss/jasm.html) to parse all the class files for
references and definitions and squirt them into a flat file to sort
alphabetically by fully qualified signature name and dedup.

Now look for definitions without references or vice versa and research
them.

You might need an external sort to deal with the volume. See
http://mindprod.com/jgloss/sort.html

 

[Chris Smith]

BTW, you won't be able to find unused constants (by which I take it you mean
static final int/bool/String fields initialised to constant values), since uses
of such fields are inlined by the compiler and so would all show up as "unused"
by any byte-code-level analyser. You may be able to find a source-level
analyser that would do the job, but I wouldn't say much for your chances of
finding one that works well since source-level analysis is /much/ harder than
bytecode level (especially since Java5).

It's worth noting that, in the context of an Eclipse plugin, you have
access to the Eclipse JDT's parse tree representation of the source
code. That makes this considerably easier than it might seem. I don't
know if you can programmatically invoke the References->In Workspace
function... but if so, then the requested plugin becomes almost trivial
to write.

So, just saying that it might not be as difficult as it sounds to write
this things from scratch, because Eclipse has most of the tools that you
need.

--
www.designacourse.com
The Easiest Way To Train Anyone... Anywhere.

Chris Smith - Lead Software Developer/Technical Trainer
MindIQ Corporation