I know you said you have Java experience, but it sounds like it's not a lot and so sticking with Java doesn't seem like a necessity to me in this context. I don't know Java so I'm not going to give you any suggestions that include it, but hopefully others here will.

Websites. Learn WordPress and basic Web Dev stuff: JS, Sass (instead of CSS), and HTML. In my world it seems everyone needs a website, and I could make ~$50-75/hour~ $50-60 in my small-ish area (300,000 in the tri-county area). Basic, nice, professional websites are not impossible, you can do it :)

EDIT: I lowered the hourly rate. I might've exaggerated. See https://skillcrush.com/2014/03/11/how-to-charge-rates-web-de....