What is manifest file in Android?

Question

Can anybody explain me in simple words what is the use of Manifest file and R.java file in android.

Why do we need these files while making an application?

Answer 1

In short terms Manifest provide the basic information of the application to Android Operating system.

For example say you have a feature in your app that scans a QR code which requires your app to access camera that won't work until unless you get the consent of the user to access their's phone camera which is done by runtime permissions.These permissions needs to be defined in the Manifest file for Android OS to know that this app will be using something related to camera of user's phone.

1. The manifest file describes essential information about your app to the Android build tools, the Android operating system, and Google Play.
2. The permissions that the app needs in order to access protected parts of the system or other apps.
3. The hardware and software features the app requires.