If you're just getting started, you may want to spend a bit of time in C#. Having worked with both Java and C# since their respective initial releases, I continue to remain far more satisfied with the language design decisions of C# over that of Java. If you have to work with the JVM, then fortunately, Kotlin is an excellent alternative and rivals very closely with that of C# in more ways than not.
Funny enough... I vowed three different times since 2010 that I would personally not get involved with another Java enterprise project again only to be lured back in for one reason or another. Each time only reinforced my complete dissatisfaction working with the language - especially on large enterprise projects.
Now that .NET is open source and multi-platform and NodeJS has a prominent foothold in enterprise, and Kotlin is now Google's preferred language for Android, I will never go back to another Java project again. But... that's just me. 😉