Hello Kotlin!

For centuries programmers start with "Hello World!". Why shouldn't we?

Run "Hello World!" online

https://play.kotlinlang.org/

Run "Hello World!" with kotlin

/*
   HelloWorld.kt
   Welcome to Kotlin!
*/

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

Let's compile it to Java Bytecode:

kotlinc HelloWorld.kt

And run it with the kotlin command.

kotlin HelloWorldKt

Run "Hello World!" as a jar

To enable running our app without an installed kotlin, we simply include the batteries:

kotlinc HelloWorld.kt -include-runtime -d HelloWorld.jar

And then run it as any other Java jar:

java -jar HelloWorld.jar

Compile to machine code

Kotlin can be compiled directly to native machine code on many architectures:

kotlinc-native HelloWorld.kt -o HelloWorld

Inspect our output and run it:

ldd HelloWorld.kexe

./HelloWorld.kexe

Run a command line script

You want a scripting laguage? Here we go:

kotlin HelloWorld.kts

Use the REPL

(Read Evaluate Print Loop)

❯ kotlin
Welcome to Kotlin version 1.9.10 (JRE 21+35)
Type :help for help, :quit for quit
>>> println("Hello World!")
Hello World!
>>> :quit