Kotlin is a statically-typed programming language developed by JetBrains. It runs on the Java Virtual Machine (JVM) and can be used to develop Android applications.
What are the key features of Kotlin?
Kotlin offers features like null safety, concise syntax, extension functions, coroutines for asynchronous programming, smart casts, and more.
Explain null safety in Kotlin.
Kotlin’s type system distinguishes between nullable and non-nullable types, helping to prevent NullPointerExceptions. Nullable types are marked with ?.
What are data classes in Kotlin?
Data classes are used to create classes that only hold data. Kotlin automatically generates equals(), hashCode(), toString(), and copy() methods for data classes.
What is the purpose of lateinit in Kotlin?
lateinit is used to declare non-null variables that will be initialized later. It is mainly used with properties of non-null types.
What are companion objects in Kotlin?
Companion objects are similar to static methods in Java. They allow defining methods or properties that can be accessed without creating an instance of the class.
Explain sealed classes in Kotlin.
Sealed classes are used to represent restricted class hierarchies. They can have a specific set of subclasses defined within the sealed class declaration.
What is the difference between val and var in Kotlin?
val is used to declare read-only variables (immutable), while var is used to declare mutable variables (read-write).
What are higher-order functions in Kotlin?
Higher-order functions are functions that take other functions as parameters or return functions.
What are extension functions in Kotlin?
Extension functions allow adding new functionality to existing classes without modifying their source code.
Explain the use of coroutines in Kotlin.
Coroutines are used for asynchronous programming in Kotlin. They allow writing asynchronous code in a sequential manner, making it easier to understand and maintain.
What is the Elvis operator (?:) in Kotlin?
The Elvis operator is used to provide a default value when a nullable variable is null.
How do you handle nullability in Kotlin?
Null safety in Kotlin can be handled using safe calls (?.), the Elvis operator (?:), the !! operator (force unwrap), and the let function.
What is a lambda expression in Kotlin?
Lambda expressions are anonymous functions that can be passed as arguments to other functions. They are defined using the {} syntax.
What is the difference between apply and with in Kotlin?
apply is an extension function that applies the provided lambda to the object and returns the object itself, while with is a standard library function that allows calling multiple methods on an object without repeating its name.
