Learning the strengths and weaknesses of the different Android programming languages will help you choose which one to learn for the apps you want to create.
Canary deployments are a good way to see how a new release will affect end users without the risk. Learn how to carry out a canary deployment in this walkthrough.
From learning JDK 8 to studying the JVM's internals, getting more efficient with your IDE, and trying your hand at Kotlin, here is some advice to be a better Java dev.