Android Interview Questions

1. What is Android development?

Ans: Android is one of the popular open-source operating systems and most commonly used in Smartphones and Tablets. This operating system is developed on the base of Linux-kernel platform-based. With the help of this Android operating system, the users can develop any type of programs and functions, which perform basic to advanced level operations. As per the latest tech reports, almost 51% of tech companies develop applications using Android operating systems.

2. What do you mean by Android SDK?

Ans: When the user wants to develop any mobile application, they need few tools and requirements. These requirements should be later satisfied by “Android SDK”, where Android SDK is a set of tools that are mainly used to develop or writing any programming scripts. One important thing about the SDK is that it contains Graphical user interfaces and enumerators in the application environment.

3. Why Android is more popular?

Ans: Below facts explain why Android is more popular;

·        More than millions of companies use the Android operating system in more than 200 countries.

·        Android is considered as a default operating system in manufacturing mobile devices.

·        Android application is an infinitely customized system.

·        Widely used in business application development and finance applications.

4. List all the android versions and names?

Ans: Android version 8.0 -> Oreo

Android 7.0-7.1.2 -> Nougat

Android 6-6.0.1 -> Marshmallow

Android 5-5.1.1 -> Lollipop

Android 4.4 -4.4.4 -> KitKat

Android 4.1 -4.3 -> Jelly bean

Android 4.0 – 4.0.4 -> Ice cream sandwich.

5. What is the difference between mobile application testing and mobile testing?

Ans: Mobile application testing is a kind of testing used on a device this contains mainly functions and features of the application. Whereas Mobile testing is also a type of testing mostly used in mobile devices and contains features like call, SMS, Contacts, Media player, and Inbuilt browsers.

6. Name the languages which are supported by Android application development?

Ans: In any Android application, Java is considered a widely-used programming language and this application also support C, C++. This language works well with Android SDK and also improve the performances.

7. What are the advantages of the Android operating system?

Ans: The following are the main advantages of using the Android operating system such as;

·        Android operating system is an open-source and platform-independent application.

·        This technology offers various mobile technologies such as Bluetooth, internet wi-fi.

8. Explain the components which are used in android architecture?

Ans: Below are the various building blocks used in Android architecture;

·        Linux kernel

·        Hardware Abstraction layer or HAL

·        Android runtime

·        Application framework or JAVA API framework

·        Applications.

9. Define the Android framework?

Ans: Android framework consists of various APIs which are developed by the Android developers with the help of codes written in the mobile device. These program codes comprise a various sets of methods and classes.

The following are the different tools also included in Android Framework;

• Create an image panel
• Text fields
• Buttons
• Activities panel -> user can interact
• Services -> these are programs run in the background
• Intents
• Broadcast receivers
• Content providers

10. Which components are mainly used in the new android project?

Ans: When you working on a new Android project, the below components are included;

·        Manifest tool -> this tool contains an XML file.

·        Build/: this consists of all build output

·        SRC/: It consists of code and various resource files.

·        RES/: this consists of bitmap images, UI strings, XML layouts, and all non-code resources.

·        Assets/: this comprises a file that should be complied with using the .apk file.

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11. Provide the core components of Android application developments?

Ans: The following are the important core components of Android application development;

• Activity managers
• Intents tools
• Services management console
• Content provider mechanism
• Fragment systems.

12. Explain briefly what is meant by activity?

Ans: Activities are just part of the mobile application, with the help of this developer can see and interact with other application devices.

 For instance: Suppose if you open an SMS option in any mobile device -> this option contains many activities such as create a new message, add a contact from the contact book, type the content in the SMS body, and now send the messages to the selected contact address.

13. What do you mean by services?

Ans: Service is a part of the android application environment, which runs only in the background and acts as independently. This doesn’t contain any graphical user interface. As we know that services are in the background so the user can continue their work and most of the time they are not aware of the services.

14. What is the intent?

Ans: The intent is an Android class type that is used by the developers to navigate from one service activity to another service activity. Usually intent displays all kinds of notifications from any mobile device to the user and then the user can respond to these notifications.

There are two types of intents are available;

·        Implicit intents

·        Explicit intents.

15. What are the differences between implicit intents and explicit intents?

Ans: The following table explains the differences between implicit and explicit extents:

16. What is the .apk extension in Android?

Ans: This .apk extension is a default format of a file which is used by any android operating systems. .apk is nothing but an Application Package kit is mainly used to install mobile applications. This type of default file contains resource files, certificates, codes, and manifest files.

17. Name the database used for the Android platform?

Ans: The database used for the android platform is SQLite; this is an open-source and serverless database management system.

18. What do you mean by ANR in android?

Ans: ANR means application not responding method, this is used to pop-up any notifications by the android systems. When the android application is working with many functions and tools at a time by this time ANR is used to respond for a long-time user action.

19. Mention the dialog boxes supported by the Android platform?

Ans: There are 4 kinds of dialog boxes supported by the android platform such as;

·        Alter dialog box -> this contains checkboxes and radio buttons to select the element.

·        Progress Dialog -> this is used to display the progress wheels or bars.

·        Time Picker Dialog -> this is used by the user to select the time.

·        Date Picker Dialog -> this is used to select the date.

20. What is orientation in Android?

Ans: Orientation is a kind of key features available in smartphone devices; this is used to rotate the mobile screen in a horizontal or vertical mode.

Android devices two types of screen orientations such as;

• Portrait screen
• Landscape screen

21. What is the importance of having an emulator within the Android environment?

Ans: The Emulator helps users to “play” with user interfaces and this becomes activate if there are any actual mobile mode is ON. Emulators support many tasks such as writing the codes, testing the codes, and debugging. Now they are considered as a safe method to test the codes if the developer needs them in the early stage of the design phase.

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22. What is the importance of XML based layouts?

Ans: The XML based layout offers consistent and standard form GUI data formats. In the android application development phase, layout information is stored in XML files, and the remaining other information is stored in source files.

23. What are containers?

Ans: A container as the name indicates which is used to store the objects and mobile widgets collectively; this is done when specific data information is required. Containers may also store information like labels data, field formats, buttons, and along with child containers.

24. When is the onstop () method invoked?

Ans: Onstop () method is invoked when an android activity is not visible to the user, this is happening because another android activity has been taken over or which is visible in front of the device activity.

25. Mention three enumerate keys when monitoring a device activity?

Ans: Below are the three enumerating keys used when monitoring a device activity such as;

• Entire lifetime activity: this happens when the user performs activity between on create and on Destroy
• Visible lifetime activity: this happens when the user performs an activity between on start and on stop.
• Foreground lifetime activity: this happens when the user performs an activity between on resume and on pause.

26. Is there a case wherein other qualifiers in multiple resources take precedence over locale?

Ans: The answer is yes, actually there are various instances used where some device qualifiers take precedence over locale activity. There are two types of exceptions are used such as MCC (mobile country code) and MNC (Mobile network code) qualifiers.

27. What are the different states wherein a process is based?

Ans: There are 4 possible states available such as;

·        Foreground activity

·        Visible activity

·        Background activity

·        Empty process activity.

28. What data types are supported by AIDL?

Ans: Below are the different data types supported by AIDL;

• String data type
• Char Sequence
• List data
• Map data type
• All common data types can be used such as int, char, long, and Boolean.

29. What is a fragment in Android?

30. What are the differences between a regular bitmap and a nine-patch image?

Ans: Firstly let me explain about the nine-patch image;

This type of nine-patch image is mainly used in an android device and SDKs tool directory.

Mainly works well with .9png

 Nine-pitch image avoids any type of image distortions.

A regular bitmap is used to store the images on the base of pixel size in the mobile device and display them too.

Final Take:

As is said earlier, Android application development is widely used in mobile technology. Most of the top mobile companies use the Android operating system to develop mobile devices. This android operating system is an independent platform and user friendly too. Because of these reasons, you can expect a large number of job openings with the highest