Creating a Kotlin Command-Line Application

Kotlin is a versatile language that allows you to build command-line applications quickly and efficiently. In this guide, we'll walk you through the steps to create a basic Kotlin command-line application.

Setting Up Your Environment

Before you start, make sure you have Kotlin installed on your system. You can install it by following the official Kotlin installation guide.

Creating a Simple Kotlin Command-Line Application

Let's create a simple command-line application that greets the user with "Hello, Kotlin!" when run.

1. Create a new Kotlin file for your application, for example, `HelloKotlin.kt`.

2. Define a `main` function where your application's code will run:

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

This code uses the `println` function to output "Hello, Kotlin!" to the command line.

3. Compile your Kotlin code using the Kotlin compiler (`kotlinc`). Open your command prompt or terminal and navigate to the directory containing your Kotlin file. Then, compile the code:

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

4. Run your application:

kotlin -classpath HelloKotlin.jar HelloKotlinKt
    

You should see "Hello, Kotlin!" printed in the terminal.

Adding Command-Line Arguments

You can accept command-line arguments in your Kotlin application. Here's an example of a Kotlin program that accepts a name as an argument and greets the user:

fun main(args: Array<String>) {
    if (args.isNotEmpty()) {
        val name = args[0]
        println("Hello, $name!")
    } else {
        println("Hello, Kotlin!")
    }
}
    

Now you can run your program with a name as an argument, like this:

kotlin -classpath HelloKotlin.jar HelloKotlinKt Alice
    

This would print "Hello, Alice!" to the terminal.

Conclusion

Kotlin is a powerful language for creating command-line applications. Whether you're building simple scripts or more complex tools, Kotlin's concise and expressive syntax makes it a great choice for command-line development.

Happy coding with Kotlin command-line applications!