Android Introduction

Android provides a variety of pre-built UI components such as structured layout objects and UI controls that allow your app's graphical user interface.

Android also offers other UI modules for special interfaces such as dialogs, notifications and menus.

In three areas, Android interface UI is divided:

  • Home Screen
  • All Apps
  • Recent Screen


The home screen is the “landing” area when we power our phone on. This interface is highly customizable and themed. Using
widgets we can create and personalize our “home” screen. All apps are the interface where the installed app is displayed, while
recent screens are the list of last used apps.

Android has changed a lot since its birth in terms of its features and interfaces. The growth of the smartphone power made
possible creating ever more appealing apps.





At the beginning, Android apps did not have a consistent interface and well defined rules so each app had a different approach,
navigation structure and buttons position.

This caused user confusion and it was one of the most important missing features compared to the iOS.

The basic building block for the user interface is a View object that is created from the View class and occupies a rectangular area on the screen and is responsible for drawing and event handling.

View is the basic widgets class, used to create interactive UI components such as buttons, text fields, etc.

The ViewGroup is a subclass of View and provides invisible container that hold other Views or other ViewGroups and define their layout properties.

At third level we have different layouts which are subclasses of ViewGroup class and a typical layout defines the visual structure for an Android user interface and can be created either at run time

using View/ViewGroup objects or you can declare your layout using simple XML file main_layout.xml which is located in the res/layout folder of your project.