Top questions with answers asked in MNC on Android

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Interview questions on Android development frequently asked in multinational corporations (MNCs), along with explanations:

  1. What is the Android Activity lifecycle? Explain each lifecycle method.
    • Answer: The Android Activity lifecycle represents the various states an Activity can be in throughout its lifetime. The lifecycle methods include:
      • onCreate(): Called when the activity is first created.
      • onStart(): Called when the activity becomes visible to the user.
      • onResume(): Called when the activity starts interacting with the user.
      • onPause(): Called when the activity is partially obscured by another activity.
      • onStop(): Called when the activity is no longer visible to the user.
      • onDestroy(): Called before the activity is destroyed. Understanding the lifecycle is crucial for managing resources and maintaining the app’s state across different scenarios.
  2. What is the difference between Serializable and Parcelable in Android?
    • Answer: Serializable and Parcelable are two interfaces used for passing data between different Android components. Serializable is a standard Java interface that serializes objects into a stream of bytes, while Parcelable is an Android-specific interface that serializes objects into a memory parcel. Parcelable is generally more efficient and faster compared to Serializable, especially for large amounts of data or in scenarios like passing data between Activities or Fragments.
  3. Explain the significance of AsyncTask in Android and its alternatives.
    • Answer: AsyncTask is a class provided by Android for performing background operations and updating the UI thread. It consists of methods like onPreExecute(), doInBackground(), and onPostExecute(). However, AsyncTask has some limitations and is deprecated in Android API level 30. Alternatives include using Kotlin Coroutines, RxJava, or the newer APIs like WorkManager and LiveData along with ViewModel for managing background tasks and UI updates efficiently.
  4. What is the purpose of the Android Manifest file (AndroidManifest.xml)?
    • Answer: The AndroidManifest.xml file is a crucial configuration file in Android development. It contains essential information about the application, such as the app’s package name, permissions required by the app, declared activities, services, broadcast receivers, and content providers, as well as other metadata necessary for the Android system to run the app correctly. It acts as a blueprint for the Android system to understand and interact with the application components.
  5. Explain the difference between Fragment and Activity in Android.
    • Answer: An Activity represents a single screen with a user interface, while a Fragment is a modular section of an Activity, with its own lifecycle and UI components that can be combined with other Fragments within a single Activity. Activities are typically used to represent full-screen user interfaces, while Fragments are more flexible and reusable components that can be dynamically added or removed from an Activity’s UI. Fragments are often used for creating multi-pane layouts on larger screens or for encapsulating reusable UI components.

Understanding these concepts is essential for Android developers, especially when aiming for positions in multinational corporations where a deep understanding of the Android framework and best practices is highly valued.