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Top 40 Android Interview Questions and Answers

Published On: December 16, 2024

Android is a dominant operating system in mobile app development, and the demand for Android developers is increasing exponentially in the job market. As it is important to have strong skills, we provide frequently asked top 40 Android interview questions and answers to help you gain proficiency with major concepts. Explore our Android course syllabus to get started. 

Android Developer Interview Questions and Answers for Freshers

Here are the Android app development interview questions and answers for freshers:

1. What is Android?

The Android operating system was created with mobile devices in mind. Touchscreen mobile devices like tablets and smartphones use it. However, these are now found in Android Auto vehicles, televisions, watches, cameras, and more.

The Linux Kernel and other open-source software are its foundation, and Google is the developer.

2. What is the latest version of Android?

Released in October 2023, Android 14 is the most recent version of the operating system. Only a few Android devices are compatible with Android 14. OS 14 will come preinstalled on some recently introduced Android handsets.

3. What are the newly added features of Android 14?

The accessibility, battery life, camera, and privacy aspects of Android 14 have all been improved. Additionally, it contains:

  • Camera extensions
  • Ultra HDR
  • Health Connect
  • Grammatical inflection
  • Predictive back
  • Per-app languages
  • Regional preferences
  • Lossless USB audio
  • Credential Manager 

4. How to check and update the Android releases?

To find out if your device has the most recent update, visit the Software Updates page.  

Your Android version can be updated and checked by:

  • Launching the Settings app on your device.
  • Reaching out to security and privacy.
  • System and update tapping.
  • To receive security updates, tap Security Update.
  • For Google Play system upgrades, tap the “System Update” button.
  • completing any actions displayed on the screen. 

5. Which parts make up the Android application?

The application manifest file, which describes each component and its interactions, binds these loosely linked components. Android applications consist of four primary components. The essential elements of an Android application are as follows: 

  • Activities
  • Services
  • Content Providers
  • Broadcast Receiver
  • Intents

6. What is an Android activity?

One of the most crucial components of the Android component is the Activity class. Every application has at least one Activity class, regardless of how little it is (both in terms of code and scalability). It can be claimed that an activity serves as the starting point for user interaction.

The Android operating system starts the code in an Activity instance by calling particular callback methods that correspond to particular stages of its lifecycle, in contrast to other programming languages where the main() function is the entry point for that program or application to begin its execution. 

7. Which four activity states are essential?

The four states are as follows:

  • Active: The activity is running in the foreground at the top of the stack.
  • Paused: The activity remains displayed but is in the background and unable to accept user input events.
  • Stopped: Because the action is invisible, it is suspended and is covered up or concealed by another activity.
  • Destroyed: The process of the action has been stopped, finished, or ended.

8. Which database does the Android platform use?

By default, Android comes with SQLite, an open-source, serverless database that is self-contained.

9. What is the architecture of an Android application?

The components of the Android architecture are: 

  • Android Framework
  • Android Applications
  • Linux Kernel
  • Libraries

10. Describe the Android SDK.

This is a collection of tools used by Android developers to create or modify apps. 

Developers may build, test, and debug their code more easily because of its graphical user interface, which simulates a portable, Android-driven environment.

Among the tools are: 

  • Dalvik Debug Monitoring Services
  • Android Emulator
  • Android Asset Packaging Tool
  • Android Debug Bridge

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11. Define DVM in Android.

DVM, or Dalvik Virtual Machine, is used to run Android apps. 

To make the application source files executable on the DVM, the Java bytecode (.class file) produced by the Java compiler is transformed into Dalvik bytecode. 

  • Android devices have a fixed processing capability, memory, and battery life.
  • The DVM design principle is to optimize itself to load quickly and function flawlessly even on devices with minimal memory or power. 

When operating several instances on a single device, this virtual machine is incredibly efficient.

12. Identify the fundamental tools needed to create an Android application.

The following are the development tools:

  • JDK
  • SDK Tools
  • Eclipse+ADT Plugin

13. Describe content provider in Android.

Information is sent between various Android applications by content sources. They let consumers access information inside an application. 

Examples: contact details, pictures, videos, and music.

14. Describe Android Toast.

In this instance, toast is a pop-up box—thus the name—that provides feedback on an action the user has taken and updates the user on the operation’s current state. 

For example, a toast stating “sending a message” appears when a smartphone user sends a message to a buddy.

15. List the four dialog boxes that Android supports.

Alert Dialog: Contains selectable components like checkboxes and/or radio buttons

Progress Dialog: Displays progress using a bar or progress wheel.

Data Picker Dialog: Allows the user to choose a date using the Date Picker Dialog.

Time Picker Dialog: The user can choose a time using the time picker dialog.

16. Why does Android frontend development require XML?

Extensible Markup Language is what XML stands for. 

  • Similar to HTML, XML is a markup language for data descriptions. 
  • Both computers and people can easily interpret XML. 
  • It is very easy to develop and scalable. 

Because XML is a lightweight language and doesn’t add weight to our layouts, we utilize it to develop our layouts on Android.

17. What is an Android broadcast receiver?

In Android, a broadcast is a system-wide event that can happen when the device boots up, receives a message, receives incoming calls, enters airplane mode, etc. 

These system-wide occurrences are handled by broadcast receivers. 

We can register for system and application events via broadcast receivers, and the registered receivers will be notified when the event occurs. 

Broadcast receivers come in primarily two varieties: 

  • Static Broadcast Receivers: Receivers that are declared in the manifest file and continue to function even when the application is closed.
  • Dynamic Broadcast Receivers: These receivers only function when the application is minimized or running.

18. What does Android’s Fragment mean?

The portion of Activity that displays a section of the User Interface (UI) on the screen is known as a fragment in Android. 

The Android activity’s modular portion is particularly useful for developing user interface designs that are adaptable and automatically change according to the screen size of the device. 

Three primary categories of fragments exist:

  • Single Fragment
  • List Fragment
  • Fragment Transaction

19. What distinguishes intent from intent filters?

To start an activity or make an existing activity do something new, an intent is an object supplied to Context.startActivity(), Context.startService(), Activity.startActivityForResult(), etc. 

Conversely, an intent filter explains the component’s capabilities (such as broadcast receivers, services, and activities). 

20. Why is it necessary to invoke setContentView() in the Activity class’s onCreate()?

This is because just one call is made to the activity life cycle onCreate() method. This is the main reason why onCreate() must call setContentView(). 

Calling this procedure in onResume(), onStart(), and other places will be inefficient because those methods are called repeatedly. 

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Android Developer Interview Questions and Answers for Experienced

21. Describe the LifecycleOwner interface and its function in LiveData object lifecycle management.

LifecycleOwner finds components (Activities, Fragments) that have observable lifecycles.

  • The Jetpack Lifecycle’s LiveData class is an observable data holder. 
  • Only when the LifecycleOwner is active (RESUMED) does it provide changes to observers, demonstrating its lifecycle awareness. 

By doing this, data updates at inappropriate periods are avoided.

22. How would you set up a custom lifecycle watcher in your application to deal with particular events?

  • Develop a class that uses LifecycleObserver.
  • Implement required lifecycle event methods.

(e.g., @OnLifecycleEvent(Lifecycle.Event.ON_RESUME)).

  • Get a reference to the LifecycleOwner (typically this) in your Activity/Fragment.
  • Make use of getLifecycle.
    • To register your observer with the LifecycleOwner, use addObserver().
  • Execute actions for particular lifecycle stages in observer methods.

23. How can you make sure that lifecycle techniques for preventing leaks include appropriate resource management (closing cursors, releasing network connections)?

  • Network connections (Volley, Retrofit): Although libraries manage connections internally, custom code must explicitly end connections (usually in onPause() or onStop()).
  • Room/CursorLoader Cursors: Observe suggested procedures when it comes to cursor closure (Room typically takes care of this, but in some situations, manual closing may be required).
  • Broadcast Receivers: To stop leakage, broadcast receivers should be unregistered in onDestroy() or onStop() (particularly if registered dynamically).
  • Location Updates: To save battery life and prevent needless resource usage, cease asking for location updates while the device is paused or stopped.

24. The Android app crashes frequently. How can the issue be resolved?

These are the best methods for resolving frequent application crashes:

  • This might be a memory problem. Verify that RAM has adequate space.
  • Use the app manager’s “settings” to clear the cache RAM and app data.
  • You may need to adjust memory management because not all applications function the same on different computers.
  • This might be a compatibility issue, which can be resolved by pre-testing the application across a wide range of devices. 

25. What are the main advantages of the Android Jetpack?

Jetpack is merely a collection of software elements, libraries, tools, and instructions to assist in creating excellent Android applications. In 2018, Google released the Android Jetpack.

Principal Advantages of Android Jetpack:

  • Creates a suggested app architecture using its constituent parts.
  • Get rid of boilerplate code.
  • Make complicated tasks simpler.
  • As libraries such as support are unbundled from the Android API and repackaged to AndroidX.package, provide backward compatibility.
  • Built-in Kotlin integration productivity feature.

26. What are the advantages of Jetpack Compose?

Google just released Jetpack Compose, a cutting-edge UI toolkit for creating native Android user interfaces. With Kotlin APIs, robust tools, and minimal code, it streamlines and speeds up UI development. 

  • Declarative 
  • Compatible
  • Boost the rate of development
  • Kotlin is concise and idiomatic.
  • Simple to keep up
  • Written in Kotlin

27. Explain Android’s Volley Library.

For Android apps, the HTTP library Volley makes networking quick and simple. 

  • Google built it, and at Google I/O 2013, it was unveiled. 
  • It was created since the Android SDK lacks a networking class that can function without affecting the user experience. 
  • Despite being a component of the Android Open Source Project (AOSP), Google declared in January 2017 that Volley would become a collection of its own. 

It controls how network requests are processed and cached, saving developers a great deal of time by preventing them from repeatedly creating the same network call/cache code.

28. Explain MVVM.

Model-View-ViewModel (MVVM) is a software architecture pattern that is widely accepted in the industry and addresses all of the shortcomings of the MVC and MVP design patterns. 

According to MVVM, the application’s main business logic should be kept apart from the data display logic (Views or UI).

The distinct MVVM code layers are:

  • Model: The abstraction of the data sources is the responsibility of this layer. Together, Model and ViewModel get and store the data.
  • View: This layer’s job is to let the ViewModel know what the user did. This layer does not have any application logic; instead, it watches the ViewModel.
  • ViewModel: The data streams that are pertinent to the view are exposed via the view model. It also acts as a connection between the View and the Model. 

29. Is Java-written Bytecode compatible with Android?

It can’t, that’s for sure.

30. What is LiveData, and what are the benefits of this Android architecture component?

The LiveData component is a type of observable data bearer, meaning that the value it contains is visible. 

  • As LiveData is a lifecycle-aware component, it operates under the stages of other application components’ lifecycles.
  • LiveData only updates the app component when the observer’s lifecycle state is active, that is, either STARTED or RESUMED. 
  • Before making any updates, LiveData always makes sure the observer is active to receive readily. 
  • LiveData prevents memory leaks by having the ability to remove the observer’s lifecycle state if it is destroyed. 
  • It facilitates the data synchronization process.

Benefits of the LiveData component:

  • The user interface is changed following the relevant data change.
  • It lowers the likelihood of an app crash by eliminating paused or destroyed activities.
  • Since LiveData is a lifecycle-aware component, there are no memory leaks.

Explore our mobile app developer course syllabus to get started.

31. What does Android’s Data Binding mean?

A support package called Data Binding offers the ability to link user interface elements within an activity or fragment to the application’s data sources.

Instead of using a programmatic approach, the library uses a declarative manner to do this binding operation. 

Here’s an example to help you fully grasp how this library operates:

The findViewById() method is used to locate a TextView widget and tie it to the ViewModel variable’s userName property: 

TextView textView = findViewById(R.id.sample_text);

textView.setText(viewModel.getUserName());

The code above is modified using the assignment expression as follows following the use of the Data Binding library:

<TextView

 android:text=”@{viewmodel.userName}” />

Data Binding Component Benefits:

  • Eliminate UI frameworks used in the activity to simplify and make the code easier to maintain.
  • Enables classes and methods to track data changes.
  • Enables the creation of objects and fills that function as collection observables.

32. Explain the Room component in Android architecture.

SQLite has been meeting Android’s database requirements since the beginning. It does not save plain old Java objects, sometimes known as POJOs, and it does not check the queries at build time, among other serious disadvantages. 

To get the SQLite database to function in the Android OS environment, developers must additionally create a lot of boilerplate code. 

All of the aforementioned difficulties are resolved by the Room component, which functions as an SQLite Object Mapping Library. 

The room can persist Java POJOs, verify queries for bugs at build time, and directly turn queries into objects.

Additionally, it uses the query result to generate LiveData results or observables. Google formally endorses and encourages developers to utilize the Room component because of its versatility. 

The following sub-components make up the room: 

  • Entity: The Room generates a table in the database for the annotated class. The class field represents the table’s columns. 
  • Data Access Objects, or DAOs, are in charge of specifying how to access databases and carry out actions.
  • Database: It is the primary access point to the relational data of the underlying application and is an abstract class that extends the RoomDatabase class.

33. Explain Android KTX with code snippets.

The KTX library is the only one that was initially released along with Jetpack. 

Android KTX is a set of Kotlin extensions created to help developers create Android apps using the Kotlin language by removing boilerplate code and enabling developers to write more concise code. KTX represents Kotlin Extensions in the name. 

An example of code both with and without the Android KTX library is shown below:

SQLite code sample without the KTX library:

db.beginTransaction()

try {

       // insert data

       db.setTransactionSuccessful()

}  

finally {

      db.endTransaction()

}

After utilizing the KTX library, the code above: 

db.transaction {

   // insert data

}

34. Describe some Android exceptions.

Examples of Android exceptions include the following:

  • IOException: An exception that is checked
  • NoSuchMethodException: An exception that has been checked
  • ClassNotFoundException: An error that has been checked
  • NullPointerException: An uncontrolled exception is called a null pointer exception.
  • ArithmeticException: An exception that is not checked
  • ArrayIndexOutOfBoundsException: An unchecked exception is the ArrayIndexOutOfBoundsException.
  • IllegalArgumentException: An exception raised by the require() precondition function is known as an IllegalArgumentException.
  • IllegalStateException: An exception raised by the check() and error() precondition methods is known as an IllegalStateException.

Unexpected actions that take place while the software is running are known as exceptions. They must be handled appropriately since they have the potential to disrupt the regular flow of execution. An application may crash if an exception is not handled.  

Here are some pointers for managing Android exceptions:

  • Before submitting a request, address any potential input problems.
  • Give variables values or utilize them as parameters in a bespoke function.
  • Sync your app’s datastore and Health Connect regularly.
  • Use back-off techniques and retries to address request problems. 

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35. Explain AAPT in Android.

The build tool known as AAPT, or Android Asset Packaging Tool, gathers and bundles resources for Android applications. The Android SDK has AAPT, which is useful for:

  • Create binary assets by combining resources.
  • Construct, modify, and access Zip-compatible files.
  • Create the R class and include resource IDs for every resource in the res directory.

In addition to being used from the command line, AAPT is utilized by Android Studio and the Android Gradle Plugin. AAPT2 is available as a stand-alone tool in Android SDK Build Tools versions 26.0.2 and up.  

AAPT can be used from the command line in the following ways:

  • Get a terminal open.
  • Navigate to the tools/directory.
  • Execute the following command:
    • Mac OS X or Linux./aapt
    • Windows: aapt.exe 

By setting android.enableAapt2=false in your gradle.properties file, you can turn off AAPT2. Next, run./gradlew — to restart the Gradle daemon.halt using the command line. 

36. What is ANR in Android?

When the primary user interface thread is blocked for longer than five seconds, Android apps may encounter the “Application Not Responding” (ANR) error: 

Definition: When a user is engaged with an app, ANRs show that the app has frozen or been stuck. Since the application could stay open rather than shut down, this is more akin to a time-out than a crash.

How It Defects: The ActivityManager and WindowManager system services are used by the Android system to keep an eye on how responsive an app is. The system shows an ANR prompt when an application isn’t responding, allowing the user to force-quit the application.  

How to stay away from ANRs: You can

  • Keep the main thread unblocked to prevent ANRs
  • Refrain from using the main thread for blocking or lengthy activities.
  • Reduce the amount of lock contention that exists between the main thread and other threads.

How to diagnose ANRs: The Android manual contains additional information regarding ANRs and how to diagnose them. Crashlytics can also be used to identify troublesome threads.  

The impact of ANRs on your app

The ASO ranking of your app may suffer as a result of ANRs. Two negative conduct levels for ANRs have been established by Google:

  • The overall threshold for poor behavior: An ANR occurs for at least 0.47% of daily active users.
  • Per-device bad behavior threshold: For a single-device model, at least 8% of daily users see an ANR. 

37. Explain ADB in Android.

A command-line utility called Android Debug Bridge (adb) enables computer-to-Android communication: 

What it does: In addition to installing and debugging programs, adb enables you to access commands that aren’t typically accessible on your device.

How it operates: A client-server application called adb links a client on your PC to a device’s daemon. The server controls communication between the client and the daemon, which executes commands sent by the client on the device.

How to utilize it: AdB can be used via Wi-Fi or USB. Although it can be installed separately, the Android SDK is frequently installed with ADB.  

Where to purchase it: AdB is compatible with Linux, macOS, and Windows.  

When utilizing ADB, keep the following in mind:

  • When connecting your phone, you must install the original manufacturer’s driver.
  • Make sure your phone has the debugging option turned on.
  • You may need to install the appropriate USB driver if your device isn’t listed.
  • If you’re experiencing problems connecting, you might try using a different USB cable or port. 

38. Describe the distinction between onSaveInstanceState() and onRestoreInstanceState() as well as the situations in which you would utilize either.

onSaveInstanceState(): The system calls the onSaveInstanceState() function before the destruction of an Activity or Fragment (such as when the screen rotates). Here, save important UI state or data. This information is kept in a bundle.

onRestoreInstanceState(): Invoked upon a configuration update, once an Activity or Fragment has been recreated. To restore the UI state, retrieve the data stored in onSaveInstanceState().

39. How can complicated data structures be preserved across configuration changes using SaveInstanceState()? 

Complex data shouldn’t be saved using onSaveInstanceState(). 

Here are some substitutes: 

  • Parcelable: To serialize bespoke objects for Bundle storage, implement Parcelable.
  • ViewModel: For data that is closely related to the Activity/Fragment lifecycle, use ViewModels.
    • They preserve data in a lifecycle-aware holder even when configurations change.
  • Room: Use a Room database to store data that is durable across configuration modifications and app restarts.
    • It makes data persistence and database interactions easier.

40. How would you create an activity that offers a consistent user experience across various setups (such as split-screen mode)?

  • OnConfigurationChanged(): To deal with configuration changes, override this function in your Activity. Recognize the new setting and modify the behavior or UI layout appropriately.
  • Responsive Layouts: Create layouts that adjust to various screen sizes and orientations by using strategies like FlexboxLayout or ConstraintLayout.
  • Test Completely: To guarantee a flawless user experience, test your activity in a variety of settings (split-screen, different screen sizes).

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Conclusion

We hope these top 40 Android app development interview questions and answers will be useful for you to ace the interviews with top companies. Enroll in our Android training in Chennai for a promising career in mobile app development. 

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