Code360 powered by Coding Ninjas X Naukri.com. Code360 powered by Coding Ninjas X Naukri.com
Table of contents
1.
Introduction
2.
Android Interview Questions for Freshers
2.1.
1. What is Android?
2.2.
2. What are some features of the Android architecture?
2.3.
3. What are the components of an Android application?
2.4.
4. What is the Scope of Android?
2.5.
5. What are the Disadvantages of Android?
2.6.
6. What are the differences between Activities and Services?
2.7.
7. What are the advantages of Android?
2.8.
8. What do we mean by the terms ADB and DDMS?
2.9.
9. List the languages used to build Android.
2.10.
10. What is an activity in Android?
3.
Android Interview Questions for Experienced
3.1.
11. What is the lifecycle of an Android activity?
3.2.
12. What is the importance of the Android Manifest file?
3.3.
13. What are some common troubleshooting techniques to detect the reasons why your Android application crashed?
3.4.
14. What is the database used in Android applications?
3.5.
15. What is a Job Scheduler?
3.6.
16. How can you optimize app performance for different Android versions and devices?
3.7.
17. Explain the benefits of using Jetpack Compose for building UI.
3.8.
18. Describe different approaches for handling background network requests in Android.
3.9.
19. How would you implement secure data storage in an Android application?
3.10.
20. Explain Dependency Injection (DI) and its benefits in Android development.
4.
Android Rapid Fire Interview Questions
4.1.
21. What is the Google Android SDK?
4.2.
22. What is the full form of AAPT?
4.3.
23. What are containers in Android?
4.4.
24. What are the different types of Orientation that are available?
4.5.
25. When is an activity said to be visible?
4.6.
26. What is the difference between a Service and a BroadcastReceiver?
4.7.
27. Briefly explain what Lint is and its purpose.
4.8.
28. What are the advantages of using Fragments in your app?
4.9.
29. How can you handle deep linking in your Android application?
4.10.
30. What is the purpose of Android Studio's Gradle build system?
4.11.
31. Describe how you would debug a memory leak in an Android app.
5.
Frequently Asked Questions
5.1.
What is the significance of the .dex file?
5.2.
What is the toast in Android?
5.3.
What is the Alert Dialog Box in Android?
5.4.
What is aapt?
5.5.
Define Android Toast.
6.
Conclusion
Last Updated: May 22, 2024
Easy

Android Interview Questions

Author Vasu Bansal
0 upvote
Create a resume that lands you SDE interviews at MAANG
Speaker
Anubhav Sinha
SDE-2 @
12 Jun, 2024 @ 01:30 PM

Introduction

In this blog, we will see some of the famous and important questions that are quite commonly asked in Android developer interview question. For smooth development of Android applications, you need to set up an IDE like Android Studio along with the Android SDK. Feel free to refer to the blog Android Studio and Environment Setup on the Coding Ninjas Website to go over the details to set up your environment.

Android Interview Questions

In this article, we have collected many Android interview questions. These questions will help you crack the Android interview and land your dream job. 

Let's see the solutions to various Android interview questions.

Android Interview Questions for Freshers

1. What is Android?

Android is a famous operating system. The founder of Android is Andy Rubin. It is an operating system designed especially for mobile phones and tablets.
 

2. What are some features of the Android architecture?

There are multiple layers in the Android stack, referred to as the Android architecture. There are five layers present in the Android architecture. They are as follows.

1. Linux Kernal
2. Libraries
3. Android Runtime
4. Android Framework
5. Android Applications

Feel free to refer to the blog Android Architecture on the Coding Ninjas Website to read and learn more about the architecture of Android.
 

3. What are the components of an Android application?

An Android application is composed of a few essential building blocks. The manifest file of our Android application provides a description of each component and binds these loosely connected components. The app's metadatadevice setupplatform requirementsexternal libraries, and required permissions are all included in the manifest file. An android app is made up of the following main components as listed below:

1. Activities
2. Services
3. Content Providers
4. Intents
5. Broadcast Receivers
6. Widgets
7. Notifications

Feel free to refer to the blog Android App Components on the Coding Ninjas Website to read more about this.

4. What is the Scope of Android?

The scope of Android is incredibly broad, extending far beyond just smartphones. Here's a closer look at the various areas it encompasses:

  • Smartphones and Tablets: Android dominates the mobile device market, powering a vast majority of smartphones and tablets. It offers a massive app ecosystem, extensive customization options, and a wide range of hardware choices to cater to different user needs and budgets.
  • Smart TVs and Displays: Android TV brings the platform to the living room, allowing users to access streaming services, play games, and interact with content on a larger screen.
  • Wearables: Android Wear is the operating system for many smartwatches. It provides features like fitness tracking, notifications, and on-the-go access to information.
  • Smart Home Devices: Android Things is a lightweight version of Android designed for internet-connected appliances. It enables them to be controlled and integrated within a smart home ecosystem.
  • Automotive: Android Auto is specifically designed for in-car entertainment and information systems. It offers features like navigation, music playback, and voice assistant integration.

In essence, Android's scope is to be a versatile operating system that functions across a wide range of mobile and connected devices. It aims to simplify user interactions and experiences across various technological domains.

5. What are the Disadvantages of Android?

While Android boasts many advantages, it's not without its drawbacks:

  • Fragmentation: Due to its open-source nature, different manufacturers can customize Android for their devices. This leads to fragmentation, where various Android versions exist simultaneously. This can cause compatibility issues with apps and result in updates rolling out at different paces for different devices.
  • Security Concerns: The openness of Android can make it more vulnerable to malware and security threats compared to iOS. Users need to be cautious about app downloads and system permissions they grant.
  • Software Updates: Timely software updates can be a challenge. Lower-end devices or those from smaller manufacturers may not receive updates for as long as high-end models, leaving them with security vulnerabilities and outdated features.
  • Inconsistent User Interface: The look and feel of Android can vary depending on the manufacturer's customizations. This can create a less streamlined user experience across different devices.
  • Bloatware: Some manufacturers pre-install unnecessary apps (bloatware) on their devices. This bloatware takes up storage space and can potentially hinder performance.

6. What are the differences between Activities and Services?

Both activities and services are components of an Android application. Yet there are some differences between them. For example, activities are designed to execute only in the foreground and can be killed by the user. On the other hand, services are designed to execute in the background. They can even run when the application is not running actually. 

Feel free to navigate to the blogs Android Activities and Android Services on the Coding Ninjas Website to have in-depth knowledge about both these topics.
 

7. What are the advantages of Android?

There are many advantages associated with Android. Unlike many other operating systems, Android is open source, i.e. everyone can use it without even paying anything. Android development is independent of the platform, i.e. one just needs to install Android Studio and set up the Android environment before actually starting making applications. Feel free to refer to the blog Android Studio and Environment Setup on the Coding Ninjas Website to go over the details to set up your environment. Android provides support for all the latest technologies like Bluetooth, Wifi, Camera, Mobile hotspots, etc.
 

8. What do we mean by the terms ADB and DDMS?

ADB stands for Android Debug Bridge. It is a command-line interface/tool. It provides us with a way to interact with the instance of an emulator through the command-line interface. 

DDMS stands for Dalvik Debug Monitor Server. It is a very famous debugging tool used for debugging Android applications. Some of the features provided by DDMS include screen capturing, network trafficking, port-forwarding services, location data spoofing, etc.

 

9. List the languages used to build Android.

Android is primarily built using a combination of the following languages:

  • Java: The core framework of Android is written in Java. It provides the foundation for building Android applications and offers features like object-oriented programming, memory management, and security.
  • Kotlin: Kotlin is a more modern, concise, and safer alternative to Java that's increasingly being used for Android development. It's fully interoperable with Java code, allowing for a gradual transition.
  • C/C++: Performance-critical parts of the Android system, especially those interacting directly with hardware, are written in C and C++. This ensures efficiency and fine-grained control over system resources.
  • XML: Android uses XML (Extensible Markup Language) for defining layouts, which specify the visual structure and organization of UI elements within an activity.

10. What is an activity in Android?

An activity is a fundamental building block of an Android application. It represents a single, focused screen with which users interact to perform actions or view information. Here's a breakdown of its key aspects:

  • Screen representation: Each activity corresponds to a specific screen in your app, similar to a window in a desktop operating system. It provides the visual elements and functionalities for users to engage with.
  • User interaction: Activities handle user input and interactions. They contain the code that responds to user touches, gestures, button clicks, and other events within the screen.
  • UI (User Interface): Activities define the UI (user interface) using a combination of Java/Kotlin code and XML layouts. The code manages the logic and behavior, while the layout files describe the visual arrangement of UI elements like buttons, text views, images, and more.
  • Lifecycle: Activities have a well-defined lifecycle that manages their creation, visibility, and destruction. They go through stages like creation, starting, resuming, pausing, stopping, and destruction, ensuring proper resource management and a smooth user experience.
  • Navigation: Activities can be launched and switched between using Intents, which are messages that specify the target activity and can optionally carry data. This allows users to navigate through different screens within the app.
Get the tech career you deserve, faster!
Connect with our expert counsellors to understand how to hack your way to success
User rating 4.7/5
1:1 doubt support
95% placement record
Akash Pal
Senior Software Engineer
326% Hike After Job Bootcamp
Himanshu Gusain
Programmer Analyst
32 LPA After Job Bootcamp
After Job
Bootcamp

Android Interview Questions for Experienced

11. What is the lifecycle of an Android activity?

An Android activity lifecycle is the different states that activity goes through in Android. To give an analogy, we consider the lifecycle of a human being. A human being goes through four stages throughout his life: the child stage, followed by the teenage stage, followed by the adult age, and at last, followed by the old-age stage. Similarly, an activity goes through multiple states. 

The activity class provides a set of six callbacks to navigate transitions between stages of the activity lifecycle. They are listed as follows:

a. onCreate()
b. onStart()
c. onResume()
d. onPause()
e.  onStop()
f.  onDestroy()
 

12. What is the importance of the Android Manifest file?

The manifests folder possesses the AndroidManifest.xml that is used to create the Android application. This file contains details about our application, such as the Android versionmetadata, the states package for the Kotlin file, and other components. It serves as a bridge between the android operating system and our application.

The directory structure of the manifests folder in our Android application looks as follows.



Feel free to refer to the blog Android Directory Structure on the Coding Ninjas Website to learn more about the directory structure of our Android projects.
 

13. What are some common troubleshooting techniques to detect the reasons why your Android application crashed?

If your Android application is frequently crashing, there could be many reasons behind this. For example, one of the reasons could be a memory issue. Some mobile phones might not have enough space and might have a low computing power processor. Sometimes, it might be the case that an application cache takes up a lot of space. So cleaning the application cache can also fix the problem. If some important files of the application are corrupted, re-installing the application can solve the problem. There can also be compatibility issues that may be causing the application to crash. Therefore before releasing the application, you should test it on different kinds of devices with different OS installed on them.
 

14. What is the database used in Android applications?

SQLite is the database that is used while creating Android applications. It is an open-source relational database (RDMS), and its engine is transactional, serverless and self-contained. The SQLite engine is properly linked with the Android application, due to which we can make access to the database faster. This is not the case with other databases.
 

15. What is a Job Scheduler?

Job Scheduler is an API for scheduling different types of jobs. It provides support for batch scheduling of jobs and performs a range of functions, including reducing battery consumption, handling network unreliability, enhancing application performance, etc.
 

16. How can you optimize app performance for different Android versions and devices?

There are several strategies for optimizing app performance across diverse devices and Android versions:

  • Leverage AndroidX libraries: These libraries provide backward compatibility features and optimized code for newer APIs, ensuring smoother performance across different Android versions.
  • Use code profilers: Tools like Android Studio's Profiler can identify performance bottlenecks within your app. You can then optimize code sections that consume excessive CPU, memory, or network resources.
  • Employ different resource configurations: Utilize resources like images and layouts that are tailored to specific screen sizes and densities. This avoids unnecessary scaling and resource loading, improving performance.
  • Implement background task management: Use techniques like AsyncTask or WorkManager to manage long-running tasks efficiently. This prevents blocking the UI thread and ensuring a responsive user experience.
  • Consider alternative data structures: Evaluate data structures used in your app. For certain situations, using efficient collections like HashMaps or SparseArrays can improve performance compared to traditional arrays or lists.

17. Explain the benefits of using Jetpack Compose for building UI.

Jetpack Compose is a modern UI framework for Android that offers several advantages:

  • Declarative and composable UI: You define the UI based on its desired state, making the code more concise and easier to maintain.
  • Improved performance: Compose utilizes a recomposition system, updating only the necessary UI components when changes occur.
  • Enhanced developer experience: Compose provides clear and intuitive APIs, aiding in building visually appealing and functional UIs.
  • Integration with existing UI code: Compose can coexist with existing View-based UI components, allowing for a gradual migration.
  • Animation capabilities: Compose offers built-in support for creating smooth and complex animations within your app.

18. Describe different approaches for handling background network requests in Android.

Here are some common approaches for handling background network requests in Android:

  • AsyncTask: This is a traditional approach where you create a separate thread to perform the network request and update the UI thread with the result upon completion. However, AsyncTask can be cumbersome to manage and may lead to memory leaks if not used cautiously.
  • Threads and Handlers: You can directly manage threads and handlers to perform network requests. This offers more control but requires careful thread synchronization to avoid UI thread blocking.
  • Volley/Retrofit: These are popular networking libraries that simplify network requests, handle queuing, caching, and provide callbacks for handling responses.
  • WorkManager: This is a recommended approach for scheduling asynchronous tasks, including network requests. It ensures efficient background task execution even when the app is in the background or restarted.
  • RxJava: For complex asynchronous operations, RxJava provides a reactive programming approach that allows for composing and managing network requests in a more declarative and maintainable way.

19. How would you implement secure data storage in an Android application?

There are various methods for secure data storage in Android, depending on the type and sensitivity of the data:

  • SharedPreferences: Suitable for simple key-value pairs of non-sensitive data like user preferences. They are stored in XML files but are not encrypted by default.
  • Internal Storage: You can write and read data files directly to the app's internal storage directory. However, this data is accessible to the app itself and potentially other apps on the device.
  • External Storage: Similar to internal storage but uses the device's external storage (SD card). Be cautious as external storage may be less secure and removable.
  • KeyStore: This offers secure storage for encryption keys and other sensitive credentials. It's hardware-backed and provides strong encryption.
  • Room Persistence Library: This is a recommended approach for storing structured data objects. Room integrates with SQLite and offers encryption capabilities for sensitive data.

20. Explain Dependency Injection (DI) and its benefits in Android development.

Dependency Injection (DI) is a design pattern that promotes loose coupling between components in your application. Instead of creating and managing dependencies within your classes, you define them externally and inject them into your code when needed.

Benefits of using DI in Android development include:

  • Improved testability: Classes with injected dependencies are easier to test in isolation as you can provide mock implementations of dependencies during testing.
  • Increased maintainability: DI promotes cleaner and more modular code by separating concerns of object creation and usage.
  • Flexibility: You can easily swap out implementations of dependencies based on context or configuration, making your app more adaptable.
  • Dependency management: Popular DI frameworks like Dagger can automatically manage dependencies and their lifecycles, simplifying code and reducing boilerplate.

Also see,  Operating System Interview Questions

Android Rapid Fire Interview Questions

21. What is the Google Android SDK?

We can easily write applications on Android enabled devices with the help of a toolset provided by Google. This toolset is known as Google Android SDK. It gives us a GUI for debugging and testing our applications.
 

22. What is the full form of AAPT?

AAPT stands for Android Asset Packaging Tool. It is again a tool that is made for developers, which helps them in creating, viewing and extracting the contents of a zip file.
 

23. What are containers in Android?

Containers are similar to their real-life counterpart’s meaning. They hold a bunch of widgets together and decide the properties and arrangements of these widgets.
 

24. What are the different types of Orientation that are available?

There are two different types of orientation that are available and can be set using the setOrientation() function. The orientations are namely HORIZONTAL or VERTICAL.
 

25. When is an activity said to be visible?

An activity is said to be visible if the user directly uses it or it is partially hiding behind another activity. It is important to note that visible activities may not be directly available in the foreground itself.

 

26. What is the difference between a Service and a BroadcastReceiver?

Services handle long-running background tasks like playing music or syncing data. - BroadcastReceivers respond to system-wide events like network changes or battery level updates.

27. Briefly explain what Lint is and its purpose.

Lint is a static code analysis tool within Android Studio that identifies potential errors, performance issues, and stylistic inconsistencies in your code. It helps you write cleaner and more efficient code.

28. What are the advantages of using Fragments in your app?

Fragments provide a modular way to manage different UI sections within an activity. They offer better code organization, easier screen rotation handling, and reusability across activities.

29. How can you handle deep linking in your Android application?

Deep linking allows users to navigate to specific content within your app through custom URLs. You can implement deep linking using libraries or frameworks that handle parsing the URL and directing users to the appropriate activity.

30. What is the purpose of Android Studio's Gradle build system?

Gradle is an automated build system used by Android Studio. It manages dependencies, builds your app, and automates various tasks associated with the development lifecycle.

31. Describe how you would debug a memory leak in an Android app.

You can use Android Studio's Memory Profiler to identify objects that are not being garbage collected properly. Analyze the leak sources and refactor your code to release unused resources and prevent memory leaks.

Frequently Asked Questions

What is the significance of the .dex file?

Dex stands for Dalvik Executable file. Android programs are compiled to this format first, i.e., .dex files, which are later zipped to a .apk file later. 

What is the toast in Android?

Sometimes, it is required to pop up a message on the user's screen in case an event occurs. This can be achieved with the help of Toast in Android.

What is the Alert Dialog Box in Android?

The Alert Dialog Box is used to display an alert message to the users of our Android application. It is used primarily to re-confirm from the users their respective decisions, thereby preventing cases of an accidental click of buttons.

What is aapt?

Aapt stands for Android Asset Packaging Tool. It's a command-line tool included in the Android SDK that primarily functions behind the scenes during development. Aapt processes and compiles various resources (layouts, images, etc.) from your app into a binary format optimized for Android, ultimately helping create the final APK (application package).

Define Android Toast.

An Android Toast is a lightweight notification that appears briefly (usually for a short duration) on top of the current activity. It's commonly used to provide non-critical user feedback, such as confirmation messages or warnings. Toasts are not modal, so they don't block user interaction with the underlying app.

Conclusion

In this article, we have extensively discussed the important Android Interview questions. By understanding these questions and practicing your answers, you can confidently approach your next Android development interview.

Recommended Readings:

 

The responses to the questions are crisp and to the point. Thus, making you all ready for Android interview questions.

If you want to learn more, check out our Android Development Course on the Coding Ninjas Website to learn everything you need to know about Android development. Do upvote our blog to help other ninjas grow. Happy Coding!

Previous article
Capgemini Interview Questions
Next article
Top Machine Learning Interview Questions & Answers (2023)
Live masterclass