In fact, if you want to enter this domain to create professional applications, you must first learn JAVA. If you are going to start creating simple applications or rely on editing resources, you can rely on some of the lessons available on the Internet to learn some Java terms. Easy for you with replication as you develop your applications.
I have referred to some courses that provide an explanation of Java in Arabic or English on this topic How to start making an Android application using Android Studio: Click on Start a new Android Studio project (welcome.jpg) In the next window you can choose a suitable name for your project and link to your site so that the program creates a package name dedicated to your application is necessary for your application to have a unique ID name that distinguishes it from any other application.