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Kotlin Introduction

Kotlin is a programming language. People use it for Android apps and for programs on a computer.

A greeting on screen

This short program shows one greeting. The greeting is the whole output.

fun main() {
    println("Hello from Kotlin")
}

Two lines in order

The first println runs before the second println. Each line appears below the one before it.

fun main() {
    println("First line")
    println("Second line")
}

A number on screen

println can also show a number by itself. This program shows the number 3.

fun main() {
    println(3)
}

Example

fun main() {
    println("Welcome")
    println("Kotlin")
    println(1)
}

Key points

  • Kotlin code in this course runs as plain programs on a computer.
  • Use println to put a value on the screen.
  • A text value in code sits inside double quotes.

In this example, the first println shows Welcome. The second println shows Kotlin below it. The third println shows the number 1 below Kotlin.

Try it Yourself

Edit the code, then press Run.

Running is simulated · Kotlin Playground

Exercise

What is Kotlin?