Saturday, 24 October 2015

35 - Android Interview Questions

1.  What is Android?
Ans. Android is an open-source, Linux based operating system that is used in mobile devices.

2. Who is the father of Android?

Ans. Rubin

3. What is an Activity?

Ans. Activity is a User interface single screen.

4. Explain life-cycle methods of android activity.

Ans. onCreate()
         onStart()
         onResume()
         onPause()
         onStop()
         onRestart()
         onDestroy()

5. Name the database used in Android.

Ans. SQLite

6. What are the advantages of Android?

Ans. 1. Open Source
         2. Platform independent
         3. It supports various technologies
         4. Highly optimized virtual machine

7. Explain Android Architecture.

Ans. Android Architecture contains 4 key components.
         1. Linux Kernel
         2. Libraries
         3. Android Framework
         4. Android Applications

8. Write important items of the Android Project.

Ans. AndroidManifest.xml
        build.xml
        bin/
        src/
        res/
        assests/

9. Write tools required for developing Android Apps.

Ans. JDK
        Eclipse + ADT Plugin
        SDK Tools

10. Which language is used to develop android apps?

Ans Java and XML

11. Write a full form of ADT.

Ans. Android Development Tools.

12. What is the difference between mobile app testing and mobile testing?

Ans. Mobile app testing means testing the application features on a mobile device and mobile testing means testing the mobile features like SMS, Call, etc.

13. Which are the core components of the Android OS?

Ans. Here are listed the core components of Android OS
        Activity
        Intents
        Services
        Content provider
        Fragments
       
14. What is an ANR notification in android?
Ans ANR means application not responding, Android display this dialog when the application has been unresponsive for a long time.

15. What is the 'Application' class?

Ans. Application class is the main class which is initialized before anything else in android. It is the primary class which contains the most important elements for the actions and the services.

16. What is the use of an Adapter in Android?

Ans. Adapters are used to connect the AdapterView with an external source of data.

17. What is the use of OnCreate() and OnStart() method?

Ans. The OnCreate() method is called only once during the lifecycle when the application starts and when the activity is recreated.
OnStart() method is called after the OnCreate() method whenever the activity becomes visible to the user.

18. Where to declare your activity so that the system can access it?

Ans. The activity can be declared in the manifest file.
        For Example:
        <manifest></manifest>
        <application></application>
        <activity android:name=".EmployeeActivity">

19. What is the intent?

Ans. Android has an intent class that displays a notification from the device to the user when the user is navigated from one activity to another.

20. How many types of intent class are there?

Ans. There are 2 types of intent classes.
         1. Implicit Intents
         2. Explicit Intents
         Implicit Intents calls the components while explicit intent invokes the activity class.

21. Where we can define the icon for the Activity?
Ans. In manifest file

22. What is a Toast Notification?
Ans. Toast Notification is a message that pops up on the top of the window. 

23. What are the different storage methods in Android?
Ans. There are two types of storage methods in Android.
         1. Shared Preferences: Store private primitive data in key-value pairs.
         2. Internal Storage: Store private data in device memory.

24. What is broadcast reciever?
Ans. It is a component of android which is used to listen important events.

25. How to start a reciever?
Ans. using sendBroadcast() method.

26. How to kill receiver?
Ans. using abortBraodcast() method.

27. How to pass data to fragment?
Ans. using setArguments() method.

28. What is fragment?
Ans. Fragment is the re-usable UI componet.

29. What are containers?
Ans. Containers hold objects and widgets together like labels, buttons, and fields, etc..

30. How do you start fragment?
Ans. Using FragmentManager, FragmentTransaction, and add() method.

31. How to destroy fragment?
Ans. using fragmenttransaction.Backstack method.

32. What are Services?
Ans. Services run in the background and acts independently.

33. What is AndroidManifest.xml file?
And. The AndroidManifest.xml file is the structured XML file. Every application must have an AndroidManifest.xml file in its root directory. It holds important information about the application.
34. What is .apk extension?

Ans. Application Package Kit is used for the installation of Android apps. It contains resource files, manifest files, certificate, and other code.

35. Which dialog boxes are used in the Android platform?
Ans. 1. AlertDialog
         2. ProgressDialog
         3. TimePickerDialog
         4. DatePickerDialog

     

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