Introduction to Kotlin

Kotlin is a modern, expressive programming language developed by JetBrains. It's designed to be fully interoperable with Java while offering enhanced features and a more concise syntax.

Key Features

• Concise and expressive syntax
• Null safety
• Functional programming support
• Interoperability with Java
• Multiplatform development capabilities

Getting Started

To begin your Kotlin journey, you'll need to install Kotlin on your system. Once installed, you can start writing Kotlin code using any text editor or IDE that supports Kotlin.

Basic Syntax

Kotlin's syntax is designed to be clean and intuitive. Here's a simple "Hello, World!" program in Kotlin:

fun main() {
    println("Hello, World!")
}

Let's break down this example:

• fun declares a function
• main() is the entry point of a Kotlin program
• println() is used to print text to the console

Variables and Data Types

Kotlin uses type inference to determine variable types. You can declare variables using val for read-only variables and var for mutable variables.

val name: String = "John"  // Immutable
var age: Int = 30          // Mutable
var height = 1.75          // Type inferred as Double

For more details on variables and data types, check out the guides on Kotlin Variables and Kotlin Data Types.

Control Flow

Kotlin supports standard control flow structures like if-else statements, when expressions (similar to switch in other languages), and various types of loops.

If-Else Statement

val number = 10
if (number > 0) {
    println("Positive number")
} else if (number < 0) {
    println("Negative number")
} else {
    println("Zero")
}

For more on conditional statements, see Kotlin If-Else Statements.

When Expression

val day = 3
val dayName = when (day) {
    1 -> "Monday"
    2 -> "Tuesday"
    3 -> "Wednesday"
    4 -> "Thursday"
    5 -> "Friday"
    else -> "Weekend"
}
println(dayName)  // Output: Wednesday

Learn more about the powerful Kotlin When Expression.

Functions

Functions in Kotlin are declared using the fun keyword. They can have parameters and return values.

fun greet(name: String): String {
    return "Hello, $name!"
}

val greeting = greet("Alice")
println(greeting)  // Output: Hello, Alice!

Explore more about Kotlin Function Basics and Kotlin Function Parameters.

Null Safety

Kotlin's type system is designed to eliminate the danger of null references. By default, variables cannot hold null values unless explicitly declared as nullable.

var nonNullable: String = "Hello"
// nonNullable = null  // This would cause a compilation error

var nullable: String? = "Hello"
nullable = null  // This is allowed

For more on handling null values safely, check out Kotlin Nullable Types and Kotlin Safe Calls.

Conclusion

This introduction covers the basics of Kotlin. As you continue your journey, explore topics like Kotlin Classes, Kotlin Coroutine Basics, and Kotlin Java Interoperability to unlock the full potential of this powerful language.