Android Interview Questions

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Android Interview Questions

Android programming is growing day by day. The questions asked by interviewers in android is given below. A list of top android interview questions and answers are given below.

1) What is Android?

Android is an open-source, linux-based operating system that is used in mobiles, tablets, televisions etc.

2) Who is the founder of Android?

Andy Rubin.

3) Explain the Android application Architecture.

Following is a list of components of Android application architecture:
  • Services: Used to perform background functionalities.
  • Intent: Used to perform the inter connection between activities and the data passing mechanism.
  • Resource Externalization: strings and graphics.
  • Notification: light, sound, icon, notification, dialog box and toast.
  • Content Providers: It will share the data between applications.

4) What are the code names of android?

  1. Aestro
  2. Blender
  3. Cupcake
  4. Donut
  5. Eclair
  6. Froyo
  7. Gingerbread
  8. Honycomb
  9. Ice Cream Sandwitch
  10. Jelly Bean
  11. Kitkat
  12. Lollipop
  13. Marshmallow

5) What are the advantages of android?

Open-source: It means no licence, distribution and development fee.
Platform-independent: It supports windows, mac and linux platforms.
Supports various technologies: It supports camera, bluetooth, wifi, speech, EDGE etc. technologies.
Highly optimized Virtual Machine: Android uses highly optimized virtual machine for mobile devices, called DVM (Dalvik Virtual Machine).

6) Does android support other language than java?

Yes, android app can be developed in C/C++ also using android NDK (Native Development Kit). It makes the performance faster. It should be used with android SDK.

7) What are the core building blocks of android?

The core building blocks of android are:
  • Activity
  • View
  • Intent
  • Service
  • Content Provider
  • Fragment etc.

8) What is activity?

Activity is like a frame or window in java that represents GUI. It represents one screen of android.

9) What are the life cycle methods of android activity?

There are 7 life-cycle methods of activity. They are as follows:
  1. onCreate()
  2. onStart()
  3. onResume()
  4. onPause()
  5. onStop()
  6. onRestart()
  7. onDestroy()

10) What is intent?

It is a kind of message or information that is passed to the components. It is used to launch an activity, display a web page, send sms, send email etc. There are two types of intents in android:
  1. Implicit Intent
  2. Explicit Intent

11) What is implicit intent in android?

Implicit intent is used to invoke the system components.

12) What is explicit intent in android?

Explicit intent is used to invoke the activity class.

13) How to call another activity in android?

  1. Intent i = new Intent(getApplicationContext(),
  2.  ActivityTwo.class);  
  3. startActivity(i);

14) What is service in android?

A service is a component that runs in the background. It is used to play music, handle network transaction etc.

15) What is the name of database used in android?

SQLite: An opensource and lightweight relational database for mobile devices.

16) What is AAPT?

AAPT is an acronym for android asset packaging tool. It handles the packaging process.

17) What is content provider?

Content providers are used to share information between android applications.

18) What is fragment?

Fragment is a part of Activity. By the help of fragments, we can display multiple screens on one activity.

19) What is ADB?

ADB stands for Android Debug Bridge. It is a command line tool that is used to communicate with the emulator instance.

20) What is NDK?

NDK stands for Native Development Kit. By using NDK, you can develop a part of app using native language such as C/C++ to boost the performance.

21) What is ANR?

ANR stands for Application Not Responding. It is a dialog box that appears if the application is no longer responding.

22) What is the Google Android SDK?

The Google Android SDK is a toolset which is used by developers to write apps on Android enabled devices. It contains a graphical interface that emulates an Android driven handheld environment and allow them to test and debug their codes.

23) What is an APK format?

APK is a short form stands for Android Packaging Key. It is a compressed key with classes,UI's, supportive assets and manifest. All files are compressed to a single file is called APK.

24) Which language does Android support to develop an application?

Android applications are written by using the java (Android SDK) and C/C++ (Android NDK).

25) What is ADT in Android?

ADT stands for Android Development Tool. It is used to develop the applications and test the applications.

26) What is View Group in Android?

View Group is a collection of views and other child views. It is an invisible part and the base class for layouts.

27) What is Adapter in Android?

An adapter is used to create a child view to present the parent view items.

28) What is nine-patch images tool in Android?

We can change bitmap images in nine sections as four corners, four edges and an axis.

29) Which kernel is used in Android?

Android is customized Linux 3.6 kernel.

30) What is application Widgets in Android?

Application widgets are miniature application views that can be embedded in other applications and receive periodic updates.

31) Which types of flags are used to run an application on Android?

Following are two types of flags to run an application in Android:
  • FLAG_ACTIVITY_NEW_TASK
  • FLAG_ACTIVITY_CLEAR_TOP

32) What is singleton class in Android?

A singleton class is a class which can create only an object that can be shared all other classes.

33) What is sleep mode in Android?

In sleep mode, CPU is slept and doesn't accept any commands from android device except Radio interface layer and alarm.

34) What do you mean by a drawable folder in Android?

In Android, a drawable folder is compiled visual resource that can use as a backgrounds, banners, icons, splash screen etc.

35) What is DDMS?

DDMS stands for Dalvik Debug Monitor Server. It gives the wide array of debugging features:
  1. Port forwarding services
  2. Screen capture
  3. Thread and heap information
  4. Network traffic tracking
  5. Location data spoofing

36) Define Android Architecture?

Android architecture consists of 4 components:
  1. Linux Kernal
  2. Libraries
  3. Android Framework
  4. Android Applications

37) What is a portable wi-fi hotspot?

The portable wi-fi hotspot is used to share internet connection to other wireless devices.

38) Name the dialog box which are supported by android?

  • Alert Dialog
  • Progress Dialog
  • Date Picker Dialog
  • Time picker Dialog

39) Name some exceptions in android?

  • Inflate Exception
  • Surface.OutOfResourceException
  • SurfaceHolder.BadSurfaceTypeException
  • WindowManager.BadTokenException

40) What are the basic tools used to develop an android app?

  • JDK
  • Eclipse+ADT plugin
  • SDK Tools

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