Photon Interactive Senior Android Developer Interview Questions and Answers

Convert vowels in a string to uppercase

• Iterate through each character in the string

• Check if the character is a vowel (a, e, i, o, u)

• If it is a vowel, convert it to uppercase

Jet Compose is a modern UI toolkit for building native Android apps using a declarative approach.

• Jet Compose is a declarative UI framework for building Android apps.

• It allows developers to create UI components using Kotlin code.

• Jet Compose simplifies UI development by eliminating the need for XML layouts.

• It provides a more flexible and efficient way to create dynamic UIs.

• Jet Compose is part of the Jetpack libraries provided by Google.

Sealed classes in Kotlin are used to represent restricted class hierarchies.

• Sealed classes can have a limited set of subclasses defined within the same file.

• They are useful for representing a fixed set of types in a hierarchy.

• Sealed classes are often used in when expressions for exhaustive checks.

Extension functions in Kotlin allow you to add new functions to existing classes without modifying their source code.

• Extension functions are defined outside of the class they extend.

• They can be called on instances of the class as if they were regular methods.

• They can access the properties and methods of the class they extend.

• Example: fun String.isEmailValid(): Boolean { ... }

• Example: fun Int.isEven(): Boolean { ... }

Null safety in Kotlin ensures that variables cannot hold null values unless explicitly specified.

• Kotlin uses nullable and non-nullable types to enforce null safety.

• The '?' operator is used to declare a variable as nullable.

• Safe call operator '?.' is used to safely access properties or methods of nullable objects.

• The '!!' operator is used for force unwrapping nullable types, but can lead to NullPointerExceptions.

Room database is a persistence library that provides an abstraction layer over SQLite to allow for more robust database access while harnessing the full power of SQLite.

• Room database simplifies database interactions by providing compile-time verification of SQL queries.

• It consists of three main components: Entity, DAO (Data Access Object), and Database.

• Entities represent tables in the database, DAOs define methods to interact with the database, and Database is the main access...read more