Top 30 Android Interview Questions and Answer for Technical Round

In this comprehensive collection of Android interview questions and answers, we cover a wide spectrum of topics to cater to developers of varying experience levels. For those aiming for advanced roles in Android development, the content delves into more complex subjects, including Dependency Injection, MVVM architecture, Kotlin vs. Java, Android Architecture Components, and Coroutines.

For beginners, we delve into the fundamentals of Android, covering essential concepts like Activities, Intents, and the Activity lifecycle. As we progress, intermediate-level topics include discussions on advanced components like Services, Broadcast Receivers, and Fragments, along with essential knowledge about the Android Support Library and the usage of AsyncTask.

1. What is Android and its architecture?

• Android is an open-source mobile operating system developed by Google. Its architecture consists of four key components: the Linux Kernel, libraries, application framework, and applications.

2. What are the key components of the Android operating system?

• The Android operating system comprises four fundamental components: the Linux Kernel, which serves as the core; libraries providing various functionalities; the application framework, offering essential services to applications; and the user-facing applications themselves.

3. Explain the Android Activity lifecycle.

• The Android Activity lifecycle is a series of states an Activity goes through, including onCreate, onStart, onResume, onPause, onStop, and onDestroy, representing the app’s interaction with the user and the system.

4. What is an Intent in Android?

• An Intent in Android is a messaging object used to request an action from another component, like starting an activity, broadcasting an event, or passing data between activities.

5. What is the difference between an Activity and a Fragment?

• An Activity is a complete user interface and represents a screen or window, while a Fragment is a modular component within an Activity, allowing for more flexible UI designs and reuse of UI elements.

6. How do you create a simple Android application using Android Studio?

• To create a basic Android application in Android Studio, follow these steps:
  a. Open Android Studio and select “Start a new Android Studio project.”
  b. Choose an activity template and configure your project.
  c. Write your code for the app’s functionality.
  d. Run the application on an emulator or physical device.

7. What is the purpose of the AndroidManifest.xml file?

• The AndroidManifest.xml file is a configuration file that provides essential information about the app to the Android system. It specifies the app’s components, permissions, and other crucial details required for proper operation.

8. Explain the concept of permissions in Android.

• Permissions in Android are security features that control access to sensitive resources, such as the camera, contacts, or location. Apps must declare the permissions they need in the AndroidManifest.xml, and users grant or deny these permissions when installing or running an app.

9. How do you handle different screen sizes and densities in Android development?

• To support various screen sizes and densities in Android development, you can create different layouts and drawables for different screen configurations using resource qualifiers like layout-large or drawable-hdpi. Android will automatically select the appropriate resources based on the device’s characteristics.

10.What is the significance of the “R.java” file?

• The “R.java” file is an auto-generated resource file in Android projects. It contains references to all the resources, such as layout files, strings, and images, making it easier to access and use these resources in your code without having to manually manage resource identifiers.