A Checkstyle Rule for OpenJDK's Local Variable Type Inference Style Guidelines

Question

Background:

OpenJDK have released a style guide for local variable type inference.

I was looking for a checkstyle built in rule that addresses it but didn't found one.

What I'm trying to get is pretty simple but I'm not that familiar with writing custom Modules.

Example:

Allow:

• instance creation, it's clear what's being created

var something = new Anything(); // OK

• it's a literal, it's obvious what type it has

var something = "literal"; // OK

Violation:

• even with good naming, no clue what's the type

var something = anything.doAnything(); // Violation

• it improves readability to use var here

Anything<Foo<Bar>> something = new Anything<>(); // Violation

• not a big deal but just for consistency

String something = "literal"; // Violation

Question:

Is there any existing rule I can extend / tweak to get the above? Should I try writing my own rule? I assume RegExp can handle some cases but not all.

Answer 1

You can tweak this one :

find it here : https://checkstyle.sourceforge.io/checks/coding/matchxpath.html#MatchXpath

Note : MatchXpath is Since Checkstyle 8.39