If you have a proficient enough understanding of Java, I'd go for the free content Udacity has on Android development.
If you're looking for Android dev with Kotlin, check out Letsbuildthatapp on youtube. He primarily does videos on iOS development, but he's published some videos with kotlin and I think more is on the way.
Once a jobbing developer I have since moved into Management. I continue with a couple of hobby projects to ensure I don't go mad. I focus on iOS/Swift and ROR.
If you have a proficient enough understanding of Java, I'd go for the free content Udacity has on Android development.
If you're looking for Android dev with Kotlin, check out Letsbuildthatapp on youtube. He primarily does videos on iOS development, but he's published some videos with kotlin and I think more is on the way.
youtu.be/PRYPafLAYps
+!
Thanks @francisco . I'll check out the Kotlin videos.