Debugging with jdb in scala

scalajdb.md

#Debugging Scala with JDB

It seems impossible to find answers on how to debug Scala with jdb on Google. I wanted to consolidate what I've learned in a easy to digest guide. Please feel free to comment with other tips I may have missed, or corrections to what's here.

##Classes Setting a breakpoint in a class is just like debugging java stop at my.package.ClassName:22

or

stop in my.package.ClassName.methodName

##Objects Setting a breakpoint in an object is usually just as simple as adding a $ to the end of the object/package name.

stop at my.package.ObjectName$:22

##Traits In general break in the implementing class. However, if there's a default implementation that you're trying to break in use the trait path with the suffix $.class for example

stop in my.package.SomeTrait$.class.foo

would set a breakpoint in the default implementation of foo in the Trait SomeTrait

FYI, while it's still early in development, there's a Scala-oriented version of jdb, called sdb, found here: https://scala-debugger.org/

Github page here: https://github.com/ensime/scala-debugger

Disclaimer is that I'm the maintainer of it, but thought I'd spread the word a little bit for those seeking something like it.

Gave a talk at ScalaSphere about the debugging tooling and whatnot. Can be found here.