If you're a Java developer want to get started with Android. Following are the things you need to know before getting started.
Eclipse was once an option. Now that's gone. Google recommends Android studio. So, have it installed.
You might notice that most of the tutorial uses an emulator. That's for the screen recording purpose.
Remember, emulator alone requires 1 GB of RAM
3 GB RAM minimum, 8 GB RAM recommended; plus 1 GB for the Android Emulator
Prefer to use an actual phone over an emulator during the development. Running the emulator along side the studio consumes extra 1 GB of RAM, that could be used efficiently for something else. App building was faster when I used a phone for the deployment. The difference was well noticeable on my 8 GB RAM machine.
Android heavily uses OOPS concepts. Hence familiarly in OOPS is a required. There is overriding, generics-collections, type casting, threads, classes, interface and inheritance. Building app natively requires a decent hands on experience in Java. XMLs are heavily used for configuration and building the UI part of the app. But this specific use of XML can be easily picked up if you've any prior programming experience. If you're a JS developer, you can try react native.
SQLite is an embedded SQL database that comes preinstalled on most devices. It is on the iPhone, iPad, and web browsers. That's the reason for it to be the most widely deployed database engine. We can use SQLitebrowser for managing our local phone db.
Also, I recommend installing Playbook for Developers by Google on your phone. Details about latest Android features, best practices, and strategies all within a single app.