Top 30 Android Interview Questions

As the Android is the most trending operating system. More than 80 percent of the users use Android phones; it will definitely increase the demand for Android Developer in the IT Company. Coding Tag provides you best 30 android interview questions and answers for fresher’s to crack interview of android programming jobs

1. Who developed Android?

Andy Rubin




2. What are the different types of components found in Android?

  • Content providers
  • Intends
  • Activity
  • Services
  • Broadcast receivers

3. Name the component that handles database and data management related issues in Android?

Content providers


4. What do you mean by the component “Activity” in the Android?

As the name represents, activity means doing something. Whenever a person clicks on an icon and opens any page or screen. This process of representing UI in Android is known as an activity.


5. What do you mean by intends in Android?

Itends are used to go from one Activity to another activity. They are also used to initiate the service and to send a broadcast.

For e.g. suppose you have performed an activity that you had opened message of your WhatsApp and after that, you again perform another activity by clicking on menu icon of the same WhatsApp.


6. What do you mean by services in Android?

Services permit all the tasks that are executing at the background of the mobile without hanging UI and allow the user to freely do another tasks such as chat, calling, browse, listening or watching video music etc.

For e.g. when you want to download any song or video, the services will help you to execute downloading in the background. The moment you click on the download button services will be initiated and it will start fetching the file from the specified URL and also inform the users about the completion of the download.


7. Which component of android is responsible for the communication between OS and Applications?

Broadcast Receivers


8. What do you mean by AAPT?

AAPT stands for Android Asset Packaging Tool capable of handling zip-compatible archives including creation, extraction, modification and content view. It acts as a core for building any Android Applications.




9. Activity Creator

Activity creator can be termed as the initial stage for building an android project. A portion of activity creators formed by the shell scripts is used to create file system structure for coding in Android IDE.


10. How can you differentiate between Mobile Testing and Application Testing?

Mobile Testing: This testing involves realistic application testing of our device and targets on features such as contacts, media player, SMS, inbuild browsers, and applications etc.

Application Testing: Application Testing involves testing of the applications such as Instagram, messenger etc present on a device. This testing targets mainly on features and functionality of the Applications.


11. What are different types of Intends?

IMPLICIT: This type of intends is used when there is a communication between two activities of the same application

EXPLICIT: This type of intends is used when there is communication between two activities of different applications


12. onCreate() method?

onCreate() method is called once throughout the activity life cycle, either at the time of activity has been destroyed or at the time when the application starts.


13. What is the application of Handler in Android?

Handler is most commonly used in communication of treads or to pass an action from background to the main thread.

Following are the two main functions of Handler:

  • Scheduling messages or in performing an action on the similar thread in future.
  • Enqueue of an action to be executed on a different thread.

14. What are the main components of Android Architecture?

Libraries

Linux Kernel

Android Applications

Android Framework


15. When a developer wants to write applications in the android environment. In which components you will get the classes and method?

Android Framework


16. How are escape characters used?

They are preceded by double backslashes ‘\\n’


17. What is the main significance of settings permissions in android app development?

Permission permits you to impose restrictions to protect code, data and functionality defects


18. When a call to onStop method happens?

This method is invoked, when an activity is no longer detectable to the user


19. What do you mean by DDMS

Dalvik Debug Monitor Server (DDMS) is referred to as the most advanced tool integrated into Android Studio capable of monitoring both emulator and real device.

It consists of large no of features or services.

Following are the list of some main services

  • port-forwarding services
  • Logcat
  • screen capture
  • thread and heap information
  • network traffic tracking
  • Incoming call, location, and SMS spoofing
  • simulating speed, latency, and network state
  • App thread statistics
  • Device file explorer
  • Incoming call and SMS spoofing
  • Location data spoofing

20. What is the main condition responsible for the occurrence of ANR errors?

This error occurs when the main method fails to update UI


21. What is the various method used to diagnose the ANR?

  • When the app is performing slow operations
  • When on the main method large calculation is going on the app
  • The main thread is not only waiting to finish a long operation but also in a deadlock situation

22. What do you mean by ANR in android and how it can be prevented?

ANR is Application Not Responding” (ANR) error. It can be prevented by creating a child thread so that the actual working of the code can be placed in that child thread which results in fewer periods of irrespective times.


23. What do you mean by Dalvik?

Dalvik present as a virtual machine where all the android applications are executed and it permits the device to run multiple virtual machines accurately and executes files in (.dex) format.


24. Which language is considered as the best language for android app development?

Java programming language, you can also program android apps in c/c++ also with the help of NDK toolset.


25. Do all mobile devices are compatible with the latest android operating system?

No, all the mobile phone is not compatible with the new advanced operating system. It depends upon the capability of the phone


26. Name the most essential file for the android system declared in the root directory containing every detail information about the application?

AndroidManifest.xml


27. What are the key items required in android project?

Src/

AndroidManifest.xml file

Bin/

Assets/

Res/

Build.xml


28. What do you mean by NinePatch Class?

NinePatch class have an extension as 9.png, allows a bitmap in 9 sections that permit extensions in nine methods i.e. 4 scaled edges in 1 axis,4 unscaled corners and the central one is allowed to be scaled in both axes


29. Name the dialog boxes that are used to select Date and Time?

DatePickerDialog is used for selecting a date and TimePickerDialog for Time selection


30. Can the Android platform support JAR deployment?

No, we cannot deploy the executable JAR. In Android, Applications are packed with the use of  AAPT (Android Asset Packaging Tool) into the .apk package i.e. Android package and then deployed onto the android platform


Related Articles:

a) Android Introduction

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