Fundamental Building Blocks of an Android Application

Application components are the essential building blocks of an android application.

They are of four types:

1)          Activities

2)          Services

3)          Content Providers

4)          Broadcast Receivers

Activity:

An activity is a component of an application which provides UI.It represents a screen with a UI.An application may contains a number of activities bound to eachother.Still, each activity is an independent entity.

Services:

A service doesn’t provide UI, user can’t see it .It is an application component that works in the background.

Content Providers:

It handles a specific set of application data. Application data can be queried or even modified by other applications through Content Providers if it permits. Also, any application, with proper permission, can query part of the content provider even.

Broadcast Receivers:

They are the building block that receive and react to broadcast announcements.

Example for a broadcast announcement from system: announcing the battery is low.

Note: All components except the Content Providers can be activated through Intents. That means Intents can be used for the communication between the aforesaid components.