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Table of contents
1.
Android Interview Questions
1.1.
Beginner-Level Android Interview Questions
1.2.
Intermediate Level Android Interview Questions
1.3.
Advance Level Android Interview Questions
2.
Conclusion
Last Updated: May 10, 2024
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Interview Questions for Android

Author Narayan Mishra
2 upvotes

Are you preparing for an Android interview? If yes, then you are at the right place. So, Android is an open-source OS(Operating System). It is designed primarily for mobile devices such as smartphones, tablets, and wearable devices. It was developed by Google and the Open Handset Alliance. It was first released in 2008. Android is based on the Linux kernel. It is written in the Java programming language.

interview questions for android

In this article, we will discuss Android interview questions. We will discuss interview questions in different levels, such as beginner, intermediate, and advance levels. Let us start with the beginner-level Android interview questions. 

Android Interview Questions

Beginner-Level Android Interview Questions

1. What do you mean by Android?

Android is an open-source OS primarily designed for mobile devices. It is based on the Linux kernel. It allows users to run third-party applications. Those applications can be downloaded from the Google Play Store or other sources. Android supports multiple hardware platforms and screen sizes, making it a versatile operating system that can run on many devices.
 

2. Why do we need Android?

We need Android for the following reasons:

  • It is a ubiquitous platform that allows users to access various applications and services.
     
  • It is an open-source platform. It can be freely modified and distributed by developers.
     
  • It can run on many devices, from low-end smartphones to high-end tablets and other gadgets. 
     
  • It is highly customizable. Users can modify the look and feel of their devices, install custom ROMs, and make other changes to the platform. 

     

3. What are the primary features of Android?

The following are the primary features of Android:

  • Customizability
     
  • Multitasking
     
  • Robust notification system
     
  • Google Play Store
     
  • Security
     
  • Google services integration
features of Android


 

4. What do you understand by activity in Android?

An activity in Android is a component representing a single screen with a UI(User Interface). It is a fundamental building block of an Android application. It provides a window where the user can interact with the application.
 

5. What do you mean by a fragment in Android?

A fragment in Android is a modular section of the activity. It represents a portion of the UI and the behavior of the application. Fragments are used to address the challenge of developing UIs. They can adapt to different screen sizes and orientations.
 

6. What is a layout in Android, and what are its different types?

A layout in Android is a collection of UI(User Interface) controls. UI controls can be buttons, text fields, images, and other widgets, that are arranged on the screen. A layout defines how these UI controls are positioned and sized on the screen. It provides the structure for the user interface of an Android application.

There are several types of layouts in Android:

  1. LinearLayout
     
  2. RelativeLayout
     
  3. ConstraintLayout
     
  4. FrameLayout
     
  5. TableLayout
layout in Android


7. What do you mean by an APK in Android?

An APK (Android Package Kit) in Android is the file format used to distribute and install applications on an Android device. It has all the necessary files and resources required to install and run an Android application on a device. It also has the compiled code, resources, assets, and manifest file.
 

8. What is a service in Android?

Service in Android is a component that runs in the background. It performs long-running operation or task that does not require user interaction. It can be used to perform tasks such as downloading data from the internet, playing music, or monitoring the device's sensors.
 

9. What do you mean by a broadcast receiver in Android?

A broadcast receiver in Android is a component that receives and responds to broadcast messages or events. 

These messages are sent by the Android system or by other applications on the device. They indicate changes in the device's state, such as the device's battery level, network connectivity, or incoming phone calls.
 

10. What is the context in Android?

The context in Android is an abstract class. The class provides access to application-specific resources and services. It represents the current state of the application or activity. It also gives information about its environment, resources, and other system-level services.

Intermediate Level Android Interview Questions

11. What do you mean by intent and its types in Android?

An Intent in Android is a messaging object. It is used to communicate between different components of an application or between various applications. It represents an action that needs to be performed, along with the necessary data and other information required to perform the action. It can be used to start activities, services, and broadcasts. 

There are two primary types of intents in Android:

  1. Explicit Intent: It starts a specific component of an application, such as an activity or service, by specifying the class name of the component to be started.
     
  2. Implicit Intent: It starts a component that can handle a specific action, regardless of its class name. 

     

12. Explain the differences between Serializable and Parcelable interfaces in Android.

Serializable and Parcelable are interfaces in Android. They allow you to serialize and deserialize objects. So they can be passed between different components of an application. However, there are some differences between them, which are mentioned below.

Serializable interfaceParcelable interface
When you serialize an object using Serializable, it creates a lot of temporary objects, which can negatively impact performance in some cases.Parcelable is generally faster than Serializable because it generates less garbage and involves less reflection. It is designed to be more efficient and can be faster in situations where performance is a concern.
It is less efficient than the Parcelable interface because it carries huge data streams.It is more efficient than Serializable. It generally produces smaller data streams.
When you implement Serializable, you don't have to write any special methods, but the serialization and deserialization process is handled entirely by the Java serialization system.It requires you to write custom code to handle the serialization and deserialization process. This gives you more control over how the object is serialized and can allow you to optimize the process for performance.
Serializable is compatible with Java, so you can use it to pass objects between Android and non-Android systems.It is specific to Android and can only be used within the Android framework.

 

13. What is the Android Manifest file, and what is its purpose?

The Android Manifest file is an XML(Extensible Markup Language) file. It provides essential information about an Android app for the Android OS. It is named "AndroidManifest.xml" and is located in the root directory of an Android project.

android manifest file

The Android Manifest file has several purposes, including

  • Declaring the app's package name.
     
  • Specifying the app's components.
     
  • Defining app permissions.
     
  • Specifying hardware and software requirements.
     
  • Declaring app metadata.
     

 

14. What do you mean by AsyncTask in Android?

AsyncTask in Android is a class that allows developers to perform background tasks or operations on a separate thread from the main UI thread. It is the best way to perform tasks that take a long time to complete without blocking the main thread. This can cause the UI to freeze and become unresponsive. The tasks can be network operations or heavy database transactions. 

An AsyncTask in Android operates by defining a set of methods that run on the UI thread. It also defines a set of methods that run on a separate worker thread. The methods that run on the UI thread include onPreExecute()onProgressUpdate(), and onPostExecute(), while the method that runs on the worker thread is doInBackground().
 

15. Explain the differences between a thread and a process in Android.

A thread and a process are two distinct concepts in Android that are used for different purposes. A thread is a lightweight unit of execution within a process. On the other hand, a process is a self-contained instance of an application or service. It runs in its own memory space, with its own virtual machine (VM). 

The following are the differences between them:

ThreadProcess
It shares resources with the parent process, which can make them more efficient in terms of resource usage.It requires more resources (such as memory) than a thread, as each process has its own set of resources.
Threads within a process share the same memory space, which can make them vulnerable to bugs and security issues.Each process is isolated from other processes, which provides better security and fault isolation. 
Switching between threads is faster, as threads share the same memory space and VM.Switching between processes is slower than switching between threads, as each process has its own memory space and VM. 

 

16. What is a content provider in Android?

Content provider in Android is a component that handles a shared set of app data. It allows you to safely share data between different applications in a standardized and secure way. They enable different apps to access, query, and modify the data stored in the same database or file without exposing the underlying implementation details.

Content Providers use a set of standardized interfaces. They use them to define how data can be accessed and modified. These interfaces are based on the CRUD (Create, Read, Update, Delete) operations that are commonly used in database management. Content Providers provide a standard, secure, and well-structured way for applications to access data.

 

17. What is an SQLite database in android?

SQLite is a lightweight RDBMS(Relational Database Management System), a software library included as a part of the Android OS. It provides a mechanism for storing and retrieving structured data. These are used in Android applications to store application data, such as user preferences, settings, and other data that needs to be persisted across application runs.

SQLite databases are stored in a file on the device's file system. Any application can have multiple SQLite databases. Each database can have multiple tables, which are used to organize the data. The data in an SQLite database is stored in rows and columns, much like in a spreadsheet.
 

18. What do you understand by the life cycle of Android activity?

The Android activity lifecycle describes how activity transitions are happening through different states as it is created, used, and destroyed. There are different states that an activity can be in. Each state with its own set of callbacks can be used to handle specific events. 

The following is the sequence of lifecycle events for an activity:

  • onCreate()
  • onStart()
  • onResume()
  • onPause()
  • onStop()
  • onRestart()
  • onDestroy()
life cycle of Android activity

By using these lifecycle methods, an Android app can gracefully handle different user interactions and system events and ensure that the app is efficient and responsive at all times.

 

19. What is a Toast in Android, and how do we create a Toast in Android?

A Toast in Android is a small pop-up message. It displays a short message to the user. It is used to show feedback or notification to the user without blocking the user's interaction with the application. To create a Toast in Android, you can use the Toast class. This class is available under android.widget package. The following steps outline the basic process of creating and displaying a Toast:

  1. Create a Toast object using the method Toast.makeText(). This method takes three parameters. The parameters are the application context, the message to display, and the duration for which the message should be displayed.
     
  2. Call the method show() on the Toast object to display the message.
     

Here is an example code snippet demonstrating how to create and display a simple Toast message:

// create a Toast object with a short duration and a message to display
Toast.makeText(getApplicationContext(), "Hello, Ninjas. This is a toast", Toast.LENGTH_SHORT).show();

 

20. What do you mean by application and activity context in Android?

The Application context is a global context. It is available throughout the application's lifecycle. It is used to access application-level resources. The resources can be the application's assets or database. You can usually obtain the application context by calling the getApplicationContext() method from the application's class.

On the other hand, the Activity context is a context that is tied to the lifecycle of an activity. It is used to access resources and services. Those resources and services are specific to an activity, such as UI widgets, layouts, and preferences. You can obtain the activity context usually by calling this keyword from the activity's class.

Advance Level Android Interview Questions

21. What are some standard techniques for optimizing the performance of an Android application?

Optimizing the performance of an Android application is very crucial for providing a good user experience. 

standard techniques for optimizing the performance of an Android application

There are some standard techniques for optimizing the performance of an Android application:

  • Reducing the number of layout hierarchies: The more complex the layout hierarchy is, the more time it takes to draw and display the user interface. Therefore, it is essential to keep the layout hierarchy as simple as possible. 
     
  • Avoid creating unnecessary objects: Creating objects can be very much expensive in terms of memory and CPU time. To avoid creating unnecessary objects, you should reuse objects wherever possible. 
     
  • Using asynchronous operations: Long-running operations, such as network requests or database queries. These should be performed asynchronously to avoid blocking the UI thread.
     
  • Use the proper data structure: Choosing the right data structure is essential for the performance of your application. 
     
  • Reduce the memory footprint of your application: The less memory your application uses, the less likely it is to be killed by the system. 

     

22. Explain the differences between targetSdkVersion and compileSdkVersion?

In Android development, there are two important version numbers that you need to specify in your app's build.gradle file. These are 

  • compileSdkVersion
  • targetSdkVersion

The compileSdkVersion specifies the version of the Android SDK(Software Development Kit ) that your app is compiled against. It means that your app can use the features. It can also use APIs provided by this version of the SDK. If you try to use an API that is not available in the compileSdkVersion, then your app will fail to build.

On the other hand, the targetSdkVersion specifies the version of the Android SDK that your app is targeting. It means that your app is designed to work best with this version of the SDK. If your app uses any deprecated features or behaviors, they will still work as expected on this version of the SDK. 
 

23. What are sensors in Android and their types?

A sensor in Android is a device or component. It can detect changes in the environment and provide the data to the Android device. 

types of sensors

These sensors are built into most modern Android devices and can include sensors such as:

  • Accelerometer: It detects the changes in the device's acceleration and orientation.
     
  • Gyroscope: It detects changes in the device's rotation and orientation.
     
  • Magnetometer: It detects changes in the device's magnetic field.
     
  • Proximity sensor: It detects when an object is nearby and adjusts the device's behavior accordingly.
     
  • Light sensor: It detects changes in the ambient light levels and adjusts the device's brightness according to it.
     
  • Barometer: It measures air pressure and can be used to determine altitude and weather conditions.
     
  • Temperature sensor: It measures the temperature of the device.
     

These sensors can be accessed through the Android Sensor API. It provides developers with a simple and consistent way to access the data from these sensors. Developers can use this data to create various applications.

 

24. What do you mean by a custom view in Android?

A custom view in Android is a user-defined component. It extends the capabilities of the built-in Android view classes. These views allow developers to create unique and customized UI components that are unavailable in the standard Android SDK.

A custom view is created by extending an existing view class, such as View, TextView, or Button. It implements custom drawing and interaction behavior. This can involve creating a new layout, creating custom attributes, and defining custom event-handling logic.

See more, SAP FICO Interview Questions and Usb debugging

 

25. What do you understand by RecyclerView in Android?

A RecyclerView in Android is a flexible and efficient view for displaying large data sets, such as lists or grids. It was introduced in Android Lollipop to improve the older ListView and GridView. It provides many benefits over these earlier implementations.

The RecyclerView is designed to be highly customizable. It provides a number of features that make it suitable for use in a variety of applications. Some of its primary key features are:

  • Reuse of views
     
  • Layout managers(such as LinearLayoutManager, GridLayoutManager, and StaggeredGridLayoutManager)
     
  • Item decorations
     
  • Item animations
     
  • Adapter-based data binding

 

26. What do you mean by an adapter in Android, and why do we need this?

An adapter in Android is a necessary component that connects a data source to a view. It creates views for data items and manages the data and views binding. It provides a bridge between the data source and the UI. It is responsible for creating the views that represent the data. It also manages the data as it is displayed to the user. An adapter extends the BaseAdapter or RecyclerView.Adapter class to provide the necessary functionality.

Adapters in Android are commonly used to populate views such as ListView, GridView, and RecyclerView. They are also used in other UI components such as Spinners, AutoCompleteTextView, and SearchView.
 

27. What do you mean by Android NDK?

The Android NDK (Native Development Kit) is a toolset. It allows developers to build Android apps using native code languages like C and C++, in addition to Java and Kotlin, which are the primary languages used for Android development.

The NDK provides a set of headers and libraries. It allows developers to write native code that can be compiled into shared libraries that can be loaded and used by an Android application. All these shared libraries can be accessed using Java Native Interface (JNI), which allows the Java code to call the native code.

There are several reasons why a developer chooses Android NDK:

  • Performance
     
  • Porting existing code
     
  • Accessing native libraries

 

28. What do you mean by a job scheduler in Android?

A job scheduler in Android is a system service. It allows developers to schedule tasks to run at specific times or under specific conditions, like when the device is charging or when the network is available.

With a job scheduler in Android, developers can offload tasks. It would otherwise require the app to run constantly or at specific intervals. This can help to improve battery life and reduce the amount of data the app uses.
 

29. Why do we use the AVD manager? 

AVD stands for Android Virtual Device. It is a tool used in Android development. It allows developers to create, configure, and manage virtual devices that simulate the behavior of real Android devices. The AVD Manager creates different virtual devices with different screen sizes, resolutions, and other hardware configurations. These virtual devices can help developers to test their applications across a range of devices and configurations without the need for physical devices.

This can be done by selecting the target API level. Then you need to specify the device's screen size, resolution, and other hardware configurations and add the required system images and optional features. When an AVD is created, it can be launched in the Android emulator. It will allow developers to test and debug their applications, like running an application on a physical device.
 

30. Explain the purpose of the Android Resource system.

The Android Resource system is an essential component of the Android OS. It is used to manage and organize the resources that are used by an application. The resources can be images, text, layouts, strings, colors, and styles.

The primary purpose of the Android Resource system is to provide a centralized location. It gives the location for storing all the resources that an application needs to function correctly. It makes it easier to manage and update all these resources throughout the application's development lifecycle.

There are some features and benefits of the Android Resource system:

  • It allows for localization.
     
  • It facilitates the development of responsive applications.
     
  • It simplifies the management of application assets.
     
  • It enables theme customization.
     

You can also check out Facebook Interview Experience to learn about Facebook’s hiring process.

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Conclusion

In this article, we have discussed Android interview questions. We have discussed interview questions in three categories: beginner, intermediate, and advance. You can check out our other interview questions blogs:

We hope this article helped you in learning about Android interview questions. You can read more such articles on our platform, Coding Ninjas Studio. You will find articles on almost every topic on our platform. Also, you can practice coding questions at Coding Ninjas to crack good product-based companies. For interview preparations, you can read the Interview Experiences of popular companies

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