Java's primary development happens on OpenJDK.

Android has their own runtime (creatively named as Android runtime), which does not run java byte code, but their own binary format. JVM class files can be compiled to that format, but the support for that always lags behind OpenJDK java versions.

Part of the reason kotlin became the de facto language on the platform was that they supported only terribly old Java at the time, that didn't even have lambdas even though it was already out.

The problem is that most of the Java libraries want to follow the desktop/server, aka the OpenJDK scene, but that would make them incompatible with Android so there was/is some incentives to bump up the version they support.