Checkstyle rule to prevent invocation of some methods and constructors

Question

Is it possible to use Checkstyle to forbid usage of some constructors or method that use system-dependent defaults (locale, charset, etc..). I prefer to enforce a policy where the programmer should be explicit about system-dependent values. So I consider the following items to be dangerous:

• all the constructors of java.io.FielWriter
  • using system-dependent encoding
• the OutputStreamWriter(OutputStream os) constructor of java.io.OutputStreamWriter
  • using system-dependent encoding
• the java.lang.String.toLowerCase() method
  • using system default locale
• The java.util.Calendar.getInstance() method
  • using system default locale and default timezone

(the list goes on, you get the picture).

Is it possible to enforce this using Checkstyle 5.5?

Answer 1

You can't do this by default. However, you can implement your own checker which checks for these methods.

The first option is to use Miscellaneous->Regexp. This is obviously only possible if you can find violations with a regexp. You will need to set illegalPattern = true. This would be a good place to start, I think.

The second options is to create your own check. See Writing Checks.

There are limitations to writing checkers. The first and most important is that you can't see other files. There isn't any cross checking. From the site:

1. You cannot determine the type of an expression.
2. You cannot see the content of other files. (although you can save processed files for use later)

This means that you cannot implement some of the code inspection features that are available in advanced IDEs like IntelliJ IDEA. For example you will not be able to implement a Check that finds redundant type casts or unused public methods.

So you couldn't check for instance that the java is calling one method which has an alternative with a Locale. You could use a blacklist of methods which you're not allowed to call. So for instance calls to new FileWriter() would check the number of parameters passed, or such like.