To become an Android app developer, you need to have a solid understanding of the following:

To become an Android app developer, you need to have a solid understanding of the following:

1. Java or Kotlin programming languages: Android apps are typically written in Java or Kotlin programming languages, so it's essential to learn at least one of these languages.

2. Android Studio: This is the official Integrated Development Environment (IDE) for Android app development. You'll need to learn how to use Android Studio to write, test, and debug your apps.

3. Android App Components: Android apps consist of several components, including activities, services, broadcast receivers, and content providers. You'll need to learn how to use these components to create functional apps.

4. Android UI Design: Android apps should have a well-designed user interface that is both aesthetically pleasing and functional. You'll need to learn how to use the Android UI toolkit, including XML layouts, views, and widgets, to create attractive and responsive UIs.

5. Database Management: Many Android apps rely on databases to store and retrieve data. You'll need to learn how to use SQLite or other database management systems to create and manage databases for your apps.

6. Networking: Most Android apps need to connect to the internet to access data or services. You'll need to learn how to use networking APIs like Volley or Retrofit to send and receive data over the internet.

7. Version Control: Version control systems like Git are essential for collaborative development and tracking changes to your codebase. You'll need to learn how to use Git to manage your codebase and collaborate with other developers.

8. Testing: Testing is an essential part of app development. You'll need to learn how to write unit tests and integration tests to ensure that your app functions as expected and identify and fix bugs.

9. Publishing to the Google Play Store: Once you've developed your app, you'll need to learn how to publish it to the Google Play Store, including creating app listings, uploading APKs, and managing app releases.

Overall, becoming an Android app developer requires a combination of technical skills and creativity. It takes time and effort to become proficient in all of these areas, but with dedication and practice, you can develop the skills you need to create high-quality Android apps.