SAP's JVM implementation has NullPointerExceptions that tell you where the null originated from, which is neat.

See slide 17 of https://oracleus.activeevents.com/2014/connect/fileDownload/...

I doubt believe it will ever or at least not anytime soon. I don't think the JVM preserves identifier names in the bytecode in a way that it can be accessed easily.

Though I do recall a long time ago reading about some JVM switches that allow that data to be accessed but with performance issues. Can't recall where I read that.

> JVM switches that allow that data to be accessed but with performance issues. Can't recall where I read that.

Would love to know how to do that.

Use the "-g:vars" switch on javac and then use a classfile reader library to inspect the LocalVariableTable.

Sadly (as one developing a lot in Java) i think it won't happen anytime soon, and the community will ideologize it as "it is even better that we don't have it". :(

I hope I will be wrong.

ps: a language where non-nullable references are the thing would be the best.

Java has finally got options, so at least it's theoretically possible to start a migration path to non-nullable. It will take decades though.

I tried to use the java Optional<T>, but the API has some points, which make it inconvenient for some usecases. (Some of these are addressed in Java 9)

As I see: unfortunately without algebraic types you cannot solve this properly, even if you address the lacking points in Optional<T>