picocli VS javawriter

Picocli allows using a compiler annotation processor to generate classes at compile time instead [0].

[0]: https://github.com/remkop/picocli/blob/main/picocli-codegen/...

Picocli is a pretty good one for writing CLI apps

"and there are simply no good command line input parsing libraries for Java."

Looks like author missed the most obvious and popular OSS one: https://picocli.info/

The command line example gave me the "ick". It is usually preferrable to parse the command line arguments into one instance of a custom "command class", rather than into a list of things. Like jcommander, picocli or jbock do.

Complex argument parsing needs to be auto-generated by libraries like picocli. Even if you need something custom, it'd be quicker to write an Annotation processor from scratch than editing that file.

https://github.com/remkop/picocli

"Picocli-based applications can be ahead-of-time compiled to a GraalVM native image, with extremely fast startup time and lower memory requirements, which can be distributed as a single executable file."

https://picocli.info/quick-guide.html

Using picocli to handle your command line options gives you the best chance to automatically generate an ArgumentCompleter script in the future, but won't help you today (other than possibly making your command line handling more standardized & easier).

Picocli

Then we released a JBang! and picocli based cli that would be, on any OS running a jvm runtime :

picocli : "a mighty tiny command line interface"

javapoet (for generating code in Java): square/javapoet: A Java API for generating .java source files. (github.com)

Resources: 1. Spring Boot Official Documentation on configuring multiple data sources: Spring Boot Reference Documentation 2. javapoet (for generating code in Java): square/javapoet: A Java API for generating .java source files. (github.com) 3. Guide to Annotation Processing in Java: Java Annotation Processing and Creating a Builder | Baeldung

Javapoet. This helped me a lot, because i wrote two generators, one for one employer, who don't like dynamic generators, so the first was to generate mappers like mapstruct does; from model to pojos and viceversa. The second one was a static testing pojo factory generator; this last one i made public (it's pretty basic and now we have projects like instancio and podam) its name is mother-factory.

> can you show an example of how you'd parse, say, a .java.in

The canonical way to do such a thing is through the java annotation processing api [1] and using a tool like java poet [2]. Before you did that, you'd probably decide if you wanted to instead use bytecode generation with a library like bytebuddy [3]

But, assuming for some reason, you wanted to torture yourself and actually consume a java.in file and apply a regex, then you'd probably pull out the "maven-replacer-plugin" [4] and configure that for the task at hand. (or use your favorite templating language plugin. There's a million of them).

Though, to be fair, this really isn't something that comes up in regular java programming due to the nature of the ecosystem. Anything you'd want to codegen likely already has a library and anything you didn't would receive (legitimate) push back.

[1] https://www.baeldung.com/java-annotation-processing-builder

[2] https://github.com/square/javapoet

[3] https://bytebuddy.net/

[4] https://github.com/beiliubei/maven-replacer-plugin

I’ve used a maven archetype before with velocitemplate. That solution was iffy so we then migrated to using https://github.com/square/javapoet to generate the java source and write it to the desired files. I think we also used the google formatter library so the files would be formatted after generating.

JavaPoet