Android has this concept of permission requesting before accessing various device resources.This helps in protecting the privacy of an Android Device user. So for example you(your apps) have to request permissions to:
Depending on the feature, the system might grant the permission automatically or might prompt the user to approve the request.
Android ContentViews Tutorial.
Android Navigation Widgets Types and Tutorial.
Android Database Types and Examples Tutorial.
Android HTTP Tutorial and Examples.
Android platform provides a powerful and flexible way of adding static content as a resource.
These static content will also be packaged into the APK file. The static content will be stored either as a resource or as an asset.
Resources belong to a given type. These types can be:
Android XML Tutorial and Examples.
Android Fragment Tutorial and Examples.
Android Alarm Tutorial and Examples.
Android Firebase Tutorial and Examples.