How to run Kotlin program using compiler

In this tutorial, we will see how to run a Kotlin program using the compiler. Make sure you've already setup Kotlin compiler earlier.

First program in Kotlin

Open any text editor (notepad, sublime, etc.) and create a HelloWorld.kt file. Make sure that the extension of this file is ".kt". Write the following program is HelloWorld.kt file:

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

Explanation:

• Line 1: Every Kotlin program starts with the main() function. Functions are created with fun keyword in Kotlin. We'll read more about functions in later sections.

• Line 2: println() function is used to print strings on the console.

Run Program through Command line:

Open the command prompt and go to the directory where you've saved your Kotlin program. Write the following command to convert the Kotlin program into jar file:

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

Explanation:

• Kotlinc: It is the command line tool that we downloaded to run Kotlin program.

• “HelloWorld.kt”: It is the name of your Kotlin program file.

• -include-runtime: By default, Kotlin compiles to Java. It will require Java libraries to run at runtime. So, to include libraries required by Kotlin at runtime, we write this.

• -d HelloWorld.jar: With this name, a jar file will be created.

To run the generated jar file, write this command:

java -jar HelloWorld.jar

You’ll see "Hello World" printed in the console.

Summary

In this tutorial, we saw how to run a program through the command line. The basic setup is complete and we will start studying about Kotlin concepts in detail from the next tutorial.