There are a lot of resources online to learn JAVA programming. I suggest you learn general programming - software development fundamentals, first. Programming languages like JAVA, C++, C#, are just variants and you'll be able to pick up one easily if you know another language, and the fundamentals. For the fundamentals, I am designing couple of YouTube videos to help. I have one ready. Have a look. Subscribe to the channel to see more videos that would broaden your fundamentals.
https://youtu.be/oHapnhejPqY

Regarding the job market, it's hot for programming in general. Doesn't need to be language specific. People are hired if they know the fundamentals and any programming language. Object oriented language like JAVA definitely helps.