Kotlin Documentation

This guide introduces Kotlin programming fundamentals, focusing on concepts and best practices for developers using the Codeunia Learn platform.

Overview

Kotlin is a modern, concise, and safe language for JVM, Android, JavaScript, Native. It interoperates with Java, offering null safety and functional features.

Kotlin Fundamentals

Variables

val for immutable, var for mutable. Type inference.

Data Types

Primitives, String, Array, collections (List, Set, Map).

Null Safety

? for nullable, !! for assertion, ?. for safe calls.

Control Flow

if, when (switch), for, while.

Functions

fun keyword, default parameters, named arguments. Lambdas.

Classes and Objects

Classes with primary/secondary constructors. Data classes, sealed classes.

Inheritance

Open classes, override methods.

Interfaces

Define contracts, multiple inheritance.

Generics

Type parameters for reusable code.

Collections

Immutable by default, mutable variants.

Best Practices

Use val, avoid null, leverage standard library.

Testing

JUnit, KotlinTest for unit tests.

Performance Optimization

Inline functions, sequences for lazy evaluation.

Deployment

Compile to JVM bytecode, JS, native.

Resources and References

• Kotlin Documentation
• Kotlin Koans
• Android Developers

Troubleshooting

Common issues include null pointer exceptions, compilation errors. Use IntelliJ IDEA.

Development Setup

Install Kotlin compiler, use IDEs like IntelliJ, Android Studio.