<p>I have to give a general note to some huge Java project for which I have but little visibility and I was wondering if there were any guidelines for determining:</p>

<ul>
<li>what number of classes per package can be considered right, to low, or to high (this project has 3.89 classes per package, which seems a bit too small for me), </li>
<li>number of methods per class? (this project has 6.54 methods per class...</li>
<li>number of lines per method? (this project has about 7 lines per method (seems pretty good to me, maybe a bit low))</li>
</ul>

<p>I should note that this question is only dealing with volumetry. I have a bunch of reports from quality tools (checkstyle, jdepend, cpd, pmd, ncss) that give me more vision about code redundancy, classes usage, bugs, etc.</p>

I think stats like that are pretty useless, how does knowing the lines per method show whether its any use to the project or not; i think you should be looking more along the lines of:
Do your packages encompass like
classes?
Do your classes work as an
entity on their own?
Do the methods
within the classes function
correctly and efficiently?
Surely other than memory usage, it doesn't matter whether the method is large or not? the other thing to look for in very protracted methods is whether the stack trace is going to be bigger than adding that functionality to a parent method.  I'd be wary of measuring a projects success based on the lines of code.