Application Components
Application components are the essential building blocks of an Android application. These components are loosely coupled by the application manifest file AndroidManifest.xml that describes each component of the application and how they interact.
There are following four main components that can be used within an Android application:
Components | Description |
Activities
|
They dictate
the UI and handle the user interaction to the smartphone screen |
Services
|
They handle
background processing associated with an application. |
Broadcast
Receivers |
They handle
communication between Android OS and applications. |
Content
Providers |
They handle
data and database management issues. |
Activities
An activity represents a single screen with a user
interface. For example, an email application might have one activity that shows
a list of new emails, another activity to compose an email, and another
activity for reading emails. If an application has more than one activity, then
one of them should be marked as the activity that is presented when the
application is launched.
An activity is implemented as a subclass of Activity class
as follows:
public
class MainActivity extends Activity {
}
 |
| Going One Activity To Another Activity |
Services
A service is a component that runs in the background to
perform long-running operations. For example, a service might play music in the
background while the user is in a different application, or it might fetch data
over the network without blocking user interaction with an activity.
A service is implemented as a subclass of Service class as
follows:
public
class MyService extends Service {
}
 |
| Service Don`t have any U.I element it Runs in Background |
Broadcast Receivers
Broadcast Receivers simply respond to broadcast messages
from other applications or from the system. For example, applications can also
initiate broadcasts to let other applications know that some data has been
downloaded to the device and is available for them to use, so this is broadcast
receiver who will intercept this communication and will initiate appropriate
action.
A broadcast receiver is implemented as a subclass of
BroadcastReceiver class and each message is broadcasted as an Intent object.
public
class MyReceiver extends BroadcastReceiver {
}
 |
| When Battery Gets Low it Broadcast A Battery low message to phone |
Content Providers
A content provider component supplies data from one
application to others on request. Such requests are handled by the methods of
the ContentResolver class. The data may be stored in the file system, the
database or somewhere else entirely.
A content provider is implemented as a subclass of
ContentProvider class and must implement a standard set of APIs that enable
other applications to perform transactions.
public
class MyContentProvider extends
ContentProvider {
}
Whats is the Best Example for Content Provider
 |
| All Contact is Provided through content provider to whatsapp |
For More Awesome Tutorial and to stay updated with our content please subscribe to my blog below is the option to subscribe and share this article.
ThankYou
EmoticonEmoticon