I've tried listening to university lectures and varies conferences talks. But, I find them distracting on the road. I've found, consuming really technical stuff to be much easier. When I can give it my full attention.

Personally, I like to listen to podcasts that cover new and upcoming technologies in the field. They could be about high level stuff or even the nitty and gritty, like new language syntax or upcoming improvements to the GC.

Though, I prefer listening to audio books just as much. And, I find them to be a great supplement for professional growth along with podcasts. When I'm not listening to fiction or sci-fi books, which isn't much. I try and listen to books about soft-skills and anything relating to software development that doesn't involve having to read code.

I can't really give you any hard suggestions here. Because, I mostly, work with languages like Ruby & JS/ES6. But, there should be similar options available for at least the JVM, if not the Java ecosystem.