50 Android Interview Questions & Answers

 

 

Q1. What is Android?

Answer

Android is a stack of software for mobile devices which includes an Operating System, middleware and some key applications. The application executes within its own process and its own instance of Dalvik Virtual Machine.

Q2. Describe Android application Architecture?

Answer

Android application architecture has the following components.They are as follows −

Services − It will perform background functionalities

Intent − It will 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

Q3. What is An Activity?

Answer
Activity performs actions on the screen.If you want to do any operations, we can do with activity

Q4. What is the APK format?

Answer

The Android packaging key is compressed with classes,UI’s, supportive assets and manifest.All files are compressed to a single file is called APK.

Q5. What is An Intent?

Answer

It is connected to either the external world of application or internal world of application ,Such as, opening a pdf is an intent and connect to the web browser.etc.

Q6. What is an explicit Intent?

Answer

Android Explicit intent specifies the component to be invoked from activity. In other words, we can call another activity in android by explicit intent.

Q7. What is an implicit Intent?

Answer

Implicit Intent doesn’t specifiy the component. In such case, intent provides information of available components provided by the system that is to be invoked.

Q8. What is An android manifest file?

Answer

Every application must have an AndroidManifest.xml file (with precisely that name) in its root directory. The manifest file presents essential information about your app to the Android system, information the system must have before it can run any of the app’s code.

Q9. What language does android support to develop an application?

Answer

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

Q10. What do ADT stands for?

Answer

ADT stands for Android development tool,This is useful to develop the applications and test the applications.

Q11. What are the tools are placed in An Android SDK?

Answer

Android SDK collaborated with Android Emulator,DDMS(Dalvik Debug Monitoring Services),AAPT(Android Asset Packaging tool) and ADB(Android debug bridge)

Q12. What is viewGroup in android?

Answer

View group is a collection of views and other child views, it is an invisible part and the base class for layouts.

Q13. What is a service in android?

Answer

The Service is like as an activity to do background functionalities without UI interaction.

Q14. What is a content provider in android?

Answer

A content provider component supplies data from one application to others on request. Such requests are handled by the methods of the ContentResolver class. A content provider can use different ways to store its data and the data can be stored in a database, in files, or even over a network.

Q15. What are the notifications available in android?

Answer

Toast Notification − It will show a pop up message on the surface of the window

Status Bar Notification − It will show notifications on status bar

Dialogue Notification − It is an activity related notification.

Q15. What is container in android?

Answer

The container holds objects,widgets,labels,fields,icons,buttons.etc.

Q16. What is ADB in android?

Answer

It is acts as bridge between emulator and IDE, it executes remote shell commands to run applications on an emulator

Q17. What is ANR in android?

Answer

ANR stands for application is not responding, basically it is a dialog box that appears when the application is not responding.

Q18. What is an Adapter in android?

Answer

The Adapter is used to create child views to represent the parent view items.

Q19. What is shared preferences in android?

Answer

Shared preferences are the simplest mechanism to store the data in XML documents.

Q20 What are the key components in android architecture?

Answer

• Linux Kernel
• Libraries
• Android Framework
• Android applications.

Q21. What does the intent filter do in android?

Answer

Intent filters are filter out the intents.

Q21. Where layouts are placed in android?

Answer

In The Layout folder, layouts are placed as XML files

Q22. What is nine-patch images tool in android?

Answer

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

Q23. How many dialog boxes do support in android?

Answer

AlertDialog, ProgressDialog,DatePickerDialog, and TimePickerDialog

Q24. What are the exceptions available in android?

Answer

InflateException,Surface.OutOfResourceException,SurfaceHolder.BadSurfaceTypeException,and WindowManager.BadTokenException

Q25. What is the order of dialog-box in android?

Answer

Positive, Neutral, Negative.

Q26. What are the different storages available in android?

Answer

Shared Preferences,Internal Storage,External Storage,SQLite Databases and Network Connection

Q27. What is a Sticky Intent in android?

Answer

Sticky Intent is also a type of intent which allows the communication between a function and a service for example,sendStickyBroadcast() is perform the operations after completion of intent also.

Q28. How to Translate in Android?

Answer

Android uses Google translator to translate data from one language into another language and placed as a string while development

Q29. How is the use of web view in Android?

Answer

WebView is UI component that can display either remote web-pages or static HTML

Q30. Why can’t you run java byte code on Android?

Answer

Android uses DVM (Dalvik Virtual Machine ) rather using JVM(Java Virtual Machine), if we want, we can get access to .jar file as a library.

Q31. How does android track the application on process?

Answer

Android provides a Unique ID to all applications is called as Linux ID,this ID is used to track each application.

Q32. How to change application name after its deployment?

Answer

It’s not truly recommended to change application name after it’s deployment, if we change, it will impact on all other internal components.

Q33. Define the application resource file in android?

Answer

JSON,XML bitmap.etc are application resources.You can injected these files to build process and can load them from the code.

Q34. How to launch an activity in android?

Answer

Using with intent, we can launch an activity.

Intent intent = new Intent(this, MyTestActivity.class);

startActivity(intent);

Q35. How do you pass the data to sub-activities android?

Answer

Using with Bundle, we can pass the data to sub activities.

Bundle bun = new Bundle();

bun.putString(“EMAIL”, “info@trenovision.com”);

Q36. What is singleton class in android?

Answer

A class which can create only an object, that object can be share able to all other classes.

Q37. What is fragment in android?

Answer

Fragment is a piece of activity, if you want to do turn your application 360 degrees, you can do this by fragment.

Q38. What is sleep mode in android?

Answer

Sleep mode mean CPU will be sleeping and it doesn’t accept any commands from android device except Radio interface layer and alarm.

Q39. Which kernal is used in android?

Answer

Android is customized Linux 3.6 kernel.

Q40. How to update UI from a service in android?

Answer

Use a dynamic broadcast receiver in the activity, and send a broadcast from the service. Once the dynamic receiver is triggered update UI from that receiver.

Q41. What folders are impotent in android project?

Answer

• AndroidManifest.xml
• build.xml
• bin/
• src/
• res/
• assets/

Q42. What are application Widgets in android?

Answer

App Widgets are miniature application views that can embedded in other applications (such as the Home screen) and receive periodic updates. These views has referred to as Widgets in the user interface, and you can publish one with an App Widget provider.

Q43. How do you find any view element into your program?

Answer

Using with findViewById we can find view element.

Q44. What is drawable folder in android?

Answer

A compiled visual resource that can used as a backgrounds,banners, icons,splash screen etc.

Q45. What are the type of flags to run an application in android?

Answer

FLAG_ACTIVITY_NEW_TASK

FLAG_ACTIVITY_CLEAR_TOP.