Wednesday, 15 January 2014

Top Android Interview Questions & Answers


01.Q) What is Android?
A) It is an open-sourced operating system that is used primarily on mobile devices, such as cell phones and tablets. It is a Linux kernel-based system that’s been equipped with rich components that allows developers to create and run apps that can perform both basic and advanced functions.

02.Q) What are the advantages of Android?
A) The following are the advantages of Android:

* The customer will be benefited from wide range of mobile applications to choose, since the monopoly of wireless carriers like Orange and AT&T will be broken by Google Android.
* Features like weather details, live RSS feeds, opening screen, icon on the opening screen can be customized
* Innovative products like the location-aware services, location of a nearby convenience store etc., are some of the additive facilities in Android.

03.Q) Mention few disadvantages of Android.
A) Every thing have some disadvantages. Like this following are some disadvantages of Android. 
·         An all-time GPRS connection to run the Android system.
 ·         Being open source it’s always vulnerable. 
 ·         Release of different Android OS for different mobile devices doesn’t allow apps to adapt with all its versions.
 ·         Apps are specific i.e. app running in one version may/may not run on another version.
 ·         Trouble to develop apps to accommodate various screen size and forms.
 ·         Wastage of memory due to a lot of background activities.
 ·         Display of ads in an application though obtained for free

04.Q) Why to use Android?
A) Android is useful because:
  • It is simple and powerful SDK
  • Licensing, Distribution or Development fee is not required
  • Easy to Import third party Java library
  • Supporting platforms are – Linux, Mac Os, Windows
05.Q) What Is the Google Android SDK?
A) The Google Android SDK is a toolset that developers need in order to write apps on Android enabled devices. It contains a graphical interface that emulates an Android driven handheld environment, allowing them to test and debug their codes.

06.Q)  What are the key components of Android Architecture?
A) Android Architecture is made up of 4 key components:
- Linux Kernel
- Libraries
- Android Framework
- Android Applications

07.Q) Describe the Android Framework.
A) The Android Framework is an important aspect of the Android Architecture. Here you can find all the classes and methods that developers would need in order to write applications on the Android environment.

08.Q) What are the Types of notification in android?
A) Following are some types of notifications in Android.
                - Tost notification
                - Status bar notification
                - Dialog notification 

09.Q) What is APK Format?
A) The APK file is compressed AndroidManifest.xml file with extension .apk, Which have application code (.dex files), resource files, and other files which is compressed into single .apk file.

10.Q) What is an action?
A) A description of something that an Intent sender desires.

11.Q) What's the difference between class, file and activity in android?
A) Class - The Class file is complied from .java file. Android will use this .class file to produce the executable apk.
File - It is a block of resources, srbitrary information. It can be any file type.
Activity - An activity is the equivalent of a Frame/Window in GUI toolkits. It is not a file or a file type it is just a class that can be extended in Android for loading UI elements on view.

12.Q) What Programming languages does Android support for application development?
A) Android applications supports using Java Programming Language. which is coded in Java and complied using Android SDK.

13.Q) What is a resource?
A) A user defined JSON, XML, bitmap, or other file, injected into the application build process, which can later be loaded from code.

14.Q) How the data will be stored in Android?
A) Internal Storage, Connecting to a network, General Preference, SQLite Database, External Storage.

15.Q)  What is .apk extension?
A) The extension for an Android Package file , which typically contains all of the files related to a single Android Application. The file itself is a compressed collection of an AndroidManifest.xml file, application code (.dex files), resource files, and other files. A Project is compiled into a single .apk file.

16.Q) What is .dex extension?
A) Androi Programs are compiled into .dex (Dalvik Executable) files, which are in turn zipped into a single.apk file on the device.  .dex files can be created automatically translating compiled applications written in the java programming language.

17.Q) What are the different phases of the Activity Life cycle?
A) As an activity transitions from state to state, it is notified of the change by calls to the following protected methods: 
1) void onCreate(Bundle savedInstanceState) 
2) void onStart() 
3) void onRestart() 
4) void onResume() 
5) void onPause() 
6) void onStop() 
7) void onDestroy() 
Taken together, these seven methods define the entire lifecycle of an activity.

18.Q) What is Intent?
A) A class (Intent) describes what a caller desires to do. The caller sends this intent to Android’s intent resolver, which finds the most suitable activity for the intent. E.g. opening a PDF file is an intent, and the Adobe Reader is the suitable activity for this intent.

19.Q) What is an Explicit Intent?
A) In an explicit intent, we actually specify the activity that is required to respond to the intent. In other words, we explicitly designate the target component. This is typically used for application internal messages. 

20.Q) What is an Implicit Intent?
A) In an implicit intent, the main power of the android design, we just declare an intent and leave it to the platform to find an activity that can respond to the intent. Here, we do not declare the target component and hence is typically used for activating components of other applications seamlessly

21.Q) What is AAPT?
A) 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.

22.Q) What does ADT stand for?
A) ADT stands for Android Development Tools The Android SDK includes several tools and utilities to help you create, test, and debug your projects.

23.Q) Differentiate Activities from Services.
A) Activities can be closed, or terminated anytime the user wishes. On the other hand, services are designed to run behind the scenes, and can act independently. Most services run continuously, regardless of whether there are certain or no activities being executed.

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