Android
applications are usually developed in the Java language (Learn programming from
JAVA training from Learn IT
Training) using the Android Software Development Kit. Learn Android by experts
and create an app of your own from Android training.
Once
developed, Android applications can be packaged easily and sold out either
through a store such as Google Play,
SlideME, Opera Mobile Store, Mobango,
F-droid and the Amazon Appstore.
Android
powers hundreds of millions of mobile devices in more than 190 countries around
the world. It's the largest installed base of any mobile platform and growing
fast. Every day more than 1 million new Android devices are activated worldwide.
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:
Activities
An
activity represents a single screen with a user interface; in-short Activity
performs actions on the screen. 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 {
}
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 {
}
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 broadcaster as an Intent object.
Public
class MyReceiver extends BroadcastReceiver {
Public void onReceive(context,intent){}
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 content provider {
Public
void onCreate() {}
}
We
will go through these tags in detail while covering application components in
individual chapters.
Additional Components
There
are additional components which will be used in the construction of above
mentioned entities, their logic, and wiring between them. These components are:
About Android Training
Developing
Android Apps is the foundation of our advanced Android curriculum. Online
course by Learn IT Training blends you theoretically and practically to build
great apps the right way. We take you through the basics and moves on to
advanced concepts in Android app development providing online classes with
highly qualified professional trainers and
will assist while attending the interviews
even after completion of course.
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