10+ Senior Android Application Developer Interview Questions and Answers

The interview questions cover various topics related to Android development, including activity and fragment life cycle, communication between fragments, MVVM design pattern, Kotlin modifiers, abstract vs interface, coroutines, background services, and Room database implementation.

• Understand the life cycle of activities and fragments in Android development

• Use communication techniques like interfaces or shared view models to communicate between parent and child fragments

• Implem...read more

Program to find duplicate words and their frequency in a given string.

• Split the string into an array of words

• Create a hashmap to store word frequency

• Iterate through the array and update the hashmap

• Print the words with frequency greater than 1

Reverse a string and demonstrate safe call and null check operator in Kotlin

• To reverse a string in Kotlin, you can use the built-in extension function 'reversed()'

• Safe call operator '?' is used to safely access properties of nullable objects without causing NullPointerException

• Null check operator '!!' is used to explicitly throw a NullPointerException if a nullable object is null

Activity life cycle is a crucial concept in Android development. Factorial and Fibonacci series are common mathematical problems. lateinit var and lazy are used for initializing variables. Var and val are used for declaring variables.

• Activity life cycle includes methods like onCreate, onStart, onResume, onPause, onStop, onDestroy.

• Factorial is the product of all positive integers up to a given number. Example: 5! = 5*4*3*2*1 = 120.

• Fibonacci series is a sequence where each numb...read more

Sensitive data should be stored securely using encryption and secure storage mechanisms.

• Use encryption algorithms like AES to encrypt sensitive data before storing it in the database.

• Store encryption keys securely, separate from the data they encrypt.

• Implement secure storage mechanisms like Android Keystore to protect sensitive data.

• Avoid storing sensitive data in plain text or easily accessible formats.

ViewModel is a class that is designed to store and manage UI-related data in a lifecycle conscious way.

• ViewModel survives configuration changes such as screen rotations.

• ViewModel is not destroyed when an activity is destroyed and recreated.

• ViewModel is typically used to hold and manage data for UI components such as activities and fragments.

SOLID is a set of five principles in object-oriented programming to make software designs more understandable, flexible, and maintainable.

• S - Single Responsibility Principle: A class should have only one reason to change.

• O - Open/Closed Principle: Software entities should be open for extension but closed for modification.

• L - Liskov Substitution Principle: Objects of a superclass should be replaceable with objects of its subclasses without affecting the functionality.

• I - Inter...read more

StateHoist is a library in Android development used for managing the lifecycle of Android components.

• StateHoist helps in handling configuration changes and other lifecycle events in Android apps.

• It simplifies the process of saving and restoring instance state of activities and fragments.

• StateHoist can be used to retain data across configuration changes, such as screen rotations.

• It provides a convenient way to manage the lifecycle of Android components without boilerplate code...read more

Develop a weather forecast app for Android platform.

• Utilize APIs like OpenWeatherMap for real-time weather data

• Include features like current weather, hourly forecast, and 7-day forecast

• Implement location-based weather updates

• Design user-friendly interface with intuitive navigation

• Incorporate push notifications for weather alerts

var is mutable and can be reassigned, val is immutable and cannot be reassigned.

• var can be reassigned with a new value, val cannot be reassigned once initialized

• var is mutable, val is immutable

• Example: var number = 5; number = 10; // valid, val number = 5; number = 10; // invalid

Kotlin is a modern programming language that is concise, expressive, and fully interoperable with Java.

• Kotlin is statically typed and supports both object-oriented and functional programming.

• It has features like null safety, extension functions, coroutines, and smart casts.

• Kotlin is officially supported for Android development by Google.