Whiz Solutions Android Developer Interview Questions and Answers

MVVM is a design pattern that separates the UI, business logic, and data layers, promoting better code organization and testability.

• MVVM stands for Model-View-ViewModel, where the ViewModel acts as an intermediary between the View and the Model.

• MVVM promotes data binding, making it easier to keep the UI in sync with the underlying data.

• Other architectures like MVC (Model-View-Controller) and MVP (Model-View-Presenter) ...read more

Data Structures and Algorithms with time and space complexity analysis

• Discuss various data structures like arrays, linked lists, trees, graphs, etc.

• Explain common algorithms like sorting, searching, dynamic programming, etc.

• Analyze time complexity using Big O notation and space complexity using memory usage

• Provide examples of code snippets with their corresponding time and space complexities

Move all zeroes to left and ones to right in an array

• Iterate through the array from both ends

• Swap the elements if left is 1 and right is 0

• Stop when left and right pointers meet

Memory leakage can cause app crashes and slow performance. It can be avoided by proper memory management and identifying the root cause.

• Avoid creating unnecessary objects

• Release unused resources

• Use memory profiling tools like Android Profiler

• Avoid static references to objects

• Use weak references when necessary

Perquisites for releasing an app on Play Store

• Creating a developer account on Google Play Console

• Complying with Google Play policies and guidelines

• Providing accurate app information and metadata

• Ensuring app compatibility with target devices

• Testing app thoroughly for bugs and crashes

• Publishing app with appropriate content rating

• Setting up monetization options and pricing

• Providing customer support and responding to user

commit() writes the changes synchronously, apply() writes the changes asynchronously.

• commit() returns a boolean value indicating success or failure, while apply() does not.

• commit() writes the changes immediately to the disk, while apply() writes the changes to the memory first and then to the disk asynchronously.

• apply() is faster than commit() as it writes the changes in the background thread.

• Use commit() when you need...read more

Alpha testing is done by internal teams before release, while beta testing is done by external users after alpha testing.

• Alpha testing is done by internal teams to identify bugs and issues before releasing the software to the public.

• Beta testing is done by external users who are not part of the development team to gather feedback and identify any remaining issues.

• Alpha testing is usually done in a controlled environmen...read more

Product Flavour is a feature in Android development that allows you to create different versions of your app with different configurations.

• Product Flavours are used to create different versions of an app for different purposes or target audiences.

• Each Product Flavour can have its own unique code, resources, and configurations.

• Product Flavours are defined in the build.gradle file of an Android project.

• Examples of Produc...read more

Yes, we can use Activity without XML by programmatically creating the UI elements.

• Activities can be created and managed entirely in code without using XML layouts.

• UI elements can be added to the activity using Java code.

• This approach is useful for creating dynamic UIs or for cases where XML layouts are not suitable.

Yes, users can downgrade an app from PlayStore by uninstalling the current version and installing an older version manually.

• Users can uninstall the current version of the app from their device.

• They can then search for the older version of the app APK file online or use a backup they may have.

• After downloading the older version APK, they can manually install it on their device.

A singleton class is a class that can only have one instance created at a time. Proguard is a tool used for code obfuscation and optimization. ViewModel is a class that stores and manages UI-related data.

• To create a singleton class, make the constructor private, create a static method to return the instance, and use a static variable to hold the instance.

• Proguard is used to shrink, optimize, and obfuscate the code in a...read more