Checkstyle vs. PMD

Question

You should definitely use FindBugs. In my experience, the false-positive rate is very low, and even the least-critical warnings it reports are worth addressing to some extent.

As for Checkstyle vs. PMD, I would not use Checkstyle since it is pretty much only concerned with style. In my experience, Checkstyle will report on a ton of things that are completely irrelevant. PMD on the other hand is also able to point out questionable coding practices and its output is generally more relevant and useful.

Both softwares are useful. Checkstyle will help you during your programming by checking your coding style i.e braces, naming etc. Simple things but very numerous!

PMD will help you by checking more complicate rules like during the design of your classes, or for more special problems like implementing correctly the clone function. Simply, PMD will check your programming style

However, both softwares suffers from similar rules sometimes bad explained. With a bad configuration, you may check things twice or two opposite things i.e "Remove useless constructors" and "Always one constructor".

If we choose one, which one should we use and why?

These tools are not competing but are complementary and should be used simultaneously.

The convention type (Checkstyle) is the glue that enables people to work together and to free up their creativity instead of spending time and energy at understanding inconsistent code.

Checkstyle examples:

• Is there javadoc on public methods ?
• Is the project following Sun naming conventions ?
• Is the code written with a consistent format ?

while PMD reminds you bad practices:

• Catching an exception without doing anything
• Having dead code
• Too many complex methods
• Direct use of implementations instead of interfaces
• Implementing the hashcode() method without the not equals(Object object) method

source: http://www.sonarsource.org/what-makes-checkstyle-pmd-findbugs-and-macker-complementary/

We use both:

• Checkstyle to make sure that everyone in the team write code in a similar maner
• PMD to find problematic code areas and next refactoring targets

If your primary place of use is while developing in eclipse, then CodePro from Instantiations will be best. Earlier it was a commercial tool, but now Google bought Instantiations so CodePro analytix is free now.

Check out http://code.google.com/javadevtools/download-codepro.html

If you reviewed Checkstyle, PMD and Findbugs rule lists, you have seen that all three provide valuable output and all three overlap to a degree and also bring their own, unique rules to the table. This is why tools like Sonar use all three.

That said, Findbugs has the most specific or niche rules (e.g. "Dubious catching of IllegalMonitorStateException" - how often are you likely to run into that?) so it is usable with little or no configuration and its warnings should be taken seriously. With Checkstyle and PMD the rules are more general and style-related so they should only be used with custom configuration files to spare the team from an avalanche of irrelevant feedback ("Tab char on line 5", "Tab char on line 6", "Tab char on line 7"... you get the picture). They also provide powerful tools to write your own advanced rules, e.g. the Checkstyle DescendentToken rule.

When using all three (especially with a tool like Sonar), all of them should be configured separately (takes at least a few days to cover all the rules) while paying attention to prevent duplication (all three tools detect that hashCode() has been overridden and equals() not, for example).

In summary, if you consider static code analysis valuable, rejecting the value any of the three provides makes no sense, but to use all three, you have to invest time to configure them to give you usable feedback.

Sonar (http://www.sonarsource.org/) is a very useful open platform to manage code quality, and includes Checkstyle, PMD, Findbugs and much more.

This also indicates that all 3 tools have their right to exist...