Building high quality software systems is what powers Picnic’s mission to revolutionize online groceries. In this post, Rick shows how we empower our Java developers using

Error Prone

, an extensible static analysis tool for Java code. What does this bring us? Catching more bugs, ensuring we have a consistent codebase, but moreover enabling us to execute large-scale automated refactorings! In fact, Picnic loves

Error Prone

so much we heavily invested in

Error Prone Support

, a new library that extends the usefulness of Error Prone itself. https://medium.com/@rick.ossendrijver/b8a566be6886 Want to see it in action? Join us next week @ Devoxx (Belgium), or the week after @ Java One (SF)! We’ll demo the tooling, explain in-depth how we use it at Picnic, and share the future of

Error Prone Support

.

Nice read, thanks for sharing!

This is now also open source 🎉 https://blog.picnic.nl/picnic-open-sources-error-prone-support-b23f9a7208b6 Here’s also a video by my colleague who goes into depth of using Error Prone (Google) and Error Prone Support (Picnic) in a Java codebase

I worked some years ago in walkmod, another OSS tool for java refactoring but I could no longer maintain it. I love to see these tools 🙂

Oh that looks pretty awesome too! Are you combining other tools or did you write it from scratch?

I did write it from scratch 🙂

@Raquel Pau Fernandez That would be awesome! Bug checks are little bit more involved, as you need to work with the AST. But refaster templates are super easy to write, as you simply write Java code with a before and after template. For example:

@BeforeTemplate
boolean before(Instant a, Instant b) {
    return a.compareTo(b) < 0;
}

@AfterTemplate
@AlsoNegation
boolean after(Instant a, Instant b) {
    return a.isBefore(b);
}

See also https://www.infoq.com/news/2022/10/error-prone-support/

Correct that is my idea. Infer those refaster templates from git patches

Adoption-wise: yes, enabling everything will lead to a lot of changes. We first disabled many rules, and then enabled them one-by-one until the point that all of them are enabled atm.

This is what I was doing in walkmod. The problem is that, usually, to understand changes you do not want to apply them as a whole because you loose why it was applied, and if there is a bug, you do not know from where