Interview Questions 11 -- 20

See more basics on Android along with interview questions

Talk on Android OS ?
                 Android is a Linux-based operating system designed primarily for touchscreen mobile
devices such as smartphones and tablet computers. Initially developed by Android, Inc., which Google backed financially and later bought in 2005.Android is the world's most popular mobile platform.
Android is a Linux-based mobile phone operating system developed by Google. Android is
unique because Google is actively developing the platform but giving it away for free to
hardware manufacturers and phone carriers who want to use Android on their devices.

What is Android SDK ?
                A software development kit that enables developers to create applications for the Android
platform. The Android SDK includes sample projects with source code, development tools,
an emulator, and required libraries to build Android applications. Applications are written
using the Java programming language and run on Dalvik, a custom virtual machine designed for
embedded use which runs on top of a Linux kernel.

What items are important in every Android project?
               These are the essential items that are present each time an Android project is created:
- AndroidManifest.xml
- build.xml
- bin/
- src/
- res/
- assets/

What is AAPT ?
                AAPT is short for Android Asset Packaging Tool. This tool provides developers with the ability to deal with zip-compatible archives, which includes creating, extracting as well as viewing its contents.

What is the use of an activityCreator ?
                An activityCreator is the first step towards the creation of a new Android project. It is made up of a shell script that will be used to create new file system structure necessary for writing codes within the Android IDE.

What are Activities ?
               An activity represents a single screen with a user interface.Suppose if there is a listview and if clicking on each row it traverse to another page ,then the screen showing listview is an activity and the next page is another activity,where each one is independent of the others.
An activity is implemented as a subclass of Activity ,that why we use

public class MainActivity extends Activity {
}

What is services ?
              A service is a component that runs in the background to perform long-running operations or to perform work for remote processes. A service does not provide a user interface.For example : Running an alarm in background
A service is implemented as a subclass of Service.

What are Content Providers ?
             They manages a shared set of application data.Data can be stored in SQLite Database,File systems,web or any other medium where application can access.
Content Providers allows to modify and use these stored data.For example : storing users contacts details,where proper permission one can get the contacts.
A content provider is implemented as a subclass of ContentProvider.

What are Broadcast receivers ?
          They responds to systems  broadcast announcements.Some of the native Broadcast are volume control, light, switch on and off, screen on and off,bluetooth etc.A broadcast receiver is just a "gateway" to other components and is intended to do a very minimal amount of work. For instance, it might initiate a service to perform some work based on the event. 
A broadcast receiver is implemented as a subclass of BroadcastReceiver.

What is the importance of XML-based layouts ?

The use of XML-based layouts provides a consistent and somewhat standard means of setting GUI definition format. In common practice, layout details are placed in XML files while other items are placed in source files.