Cfrgtkky

From time to time I see on code reviews such definitions

public class EntityConverter {

    private static final int FIRST_VERSION = 1;

    @Autowired

    private EntityRepository repository;



    public void someMethod() {

        ...

    }

    ...

}

and/or

public class EntityConverter {

    private static final int FIRST_VERSION = 1;



    @Autowired

    private EntityRepository repository;

    public void someMethod() {

        ...

    }

    ...

}

How to enforce guys to add 1 empty line between class sections (between constants, variables, methods, etc.)?

Well, your best bet would be the EmptyLineSeparator check. According to its docs, it:

checks for empty line separators after header, package, all import declarations, fields, constructors, methods, nested classes, static initializers and instance initializers.

Configure like this:

<module name="EmptyLineSeparator"/>

The tokens property controls where you want the empty lines. (At least you can choose from a list of places.)

You need at least Checkstyle 5.8, better 6.18 or later.

I did not find anything already implemented, so I wrote a regex for this check.

Quick solution with multiline regex (the code should be well formatted):

<module name="RegexpMultiline">

    <property name="format" value="^([^n ]+ )*(class|interface|enum) [^{]*{n[^n}]"/>

    <property name="message" value="Leave empty row after class/interface/enum definition!"/>

    <property name="severity" value="error"/>

    <property name="fileExtensions" value="groovy,java"/>

</module>



<module name="RegexpMultiline">

    <property name="format" value="[^n{]n}n"/>

    <property name="message" value="Leave empty row before end of class/interface/enum!"/>

    <property name="severity" value="error"/>

    <property name="fileExtensions" value="groovy,java"/>

</module>

There are a lot of threads and discussions about this:

• https://github.com/checkstyle/checkstyle/issues/5313


• https://github.com/checkstyle/checkstyle/issues/3379


• https://github.com/checkstyle/checkstyle/issues/3923