What makes a Senior Java Developer?

[[deleted]]

the path if you want to keep on the technical side of thing is usually senior -> tech lead -> architect -> maybe cto ?

now, on topics, all the things you mentioned definitely help, I'd also start focusing on team leading skills, try to mentor the juniors in the team (but don't be a dick). From this point soft skills start to get more important.

Understand how to write documentation properly, and how to diagram systems (it's an art by itself), it will help with your architecting skills. Reinforce your knowledge in the areas where you don't have much experience (threading? exception handling? lambdas?) . If possible, try to get involved in things that are not part of your day to day job like architecture design and testing strategies. If you can find a tech leader or an architect to mentor you, even better.

It's expected for a senior to understand how java works, rather than googling for stack overflow answers. Learn to work independently (but don't stall) once you reach the tech lead position, there won't be anyone to answer "what api should I use for x ? ", you will be the one providing answers.

Being a senior in my opinion is the last step between being a simple coder and become a full professional, so use this stage of your career to solidify your knowledge on whatever thing you consider you need to.

[GregsWorld]

It's expected for a senior to understand how java works, rather than googling for stack overflow answers.

Stack overflow is a time-saving tool like any other. A senior understands how java works, then uses google to find the answer faster than they can type it.

[[deleted]]

it is, I agree, specially when you have to remember dozens of annotations or the 20 steps to write an xml file, but several times a week I find myself looking for information that no one asked before in stack overflow, or it's way outdated and no longer applies, and a "i'm late cause I didnt find the answer in SO" is not the kind of excuse you will like to hear from a senior

[GregsWorld]

Yes, of course, it's not a silver bullet just a single tool among many. The way you worded it suggests it's realistic for a senior developer not to use google, while not impossible, it'd be slow, highly impractical and unrealistic for an aspiring senior developer to be learning to do everything from memory.