I would like to start off from PIEBALDconsult's comment, 10 years to only learn Java, not understand it. It takes years to learn a language and understand it... A programming language is also a language, if you pay attention, it is talking to you more than it is talking to compiler. You cannot assume a short time period like a year or two to learn and understand a language. Most of time, I have read people writing in their posts, that they didn't even know about a platform until they got their jobs and they now have a great grip over it. Ok, let me give you a few threads to see what other peoples are saying to get jobs (well at Google, Facebook etc).
https://www.quora.com/What-coding-skills-are-required-to-land-a-job-at-Google-Facebook-or-Microsoft[
^]
https://www.quora.com/Is-it-possible-to-get-a-job-at-Google-if-Im-great-at-math-but-have-very-little-experience-programming[
^]
Not only these two, there are quite a lot of other options and threads which
you should read and understand as a beginner in programming. Programming is not just about writing a source code
that compiles, runs and does something impossible. First it is about something, that you have to solve... Some problem that you're facing and you believe it can be made better in this way; algorithm. That is when some programming language jumps in. Java, C#, C++ they all offer same things (as being Object-oriented programming languages). You can learn either one of them, then develop apps in that particular language. They have their own plus points and some negative points.
As you would continue learning... You will find out, that it doesn't take 1 or 2 years to become a programmer; a real one, it takes decades or even multiples of decades to be a programmer. I would like to quote,
Any fool can write code that a computer can understand. Good programmers write code that humans can understand.
There are quite bunch of tutorials for you, to start learning Java. But, I would suggest that you go to the
official Java documentations[
^] and learn something from there..