If you're accustomed to Java, you can pick up C# quick. Most of the rules are exactly the same. You might consider giving Unity a spin; I've already completed a mobile project on it and it's relatively easy to do. If you use the Lightweight Rendering Pipeline (LWRP) (which is technically still in preview), you can cut around a lot of the programming with Shader Graph; but since it's in preview, save frequently and count on changes down the road.