Reading command line arguments in Kotlin

In this article, we will see how to pass command line arguments in Kotiln and how to access them in a program.
 
Inside the IntelliJ Idea editor, select

Run -> Edit Configurations

Add the command line parameters in Program arguments as shown below and click apply. In this case, we have added a name “John”.


We can use array notation to access the arguments. In this case, lets access the name as args[0].

fun main(args: Array<String>) {
    print("Hello " + args[0])
}

Output :

Hello John
 
In Kotlin, we can also use String template syntax for the concatenation. We can use any parameters inside ${} for this.

So, the above program can be rewritten as :

fun main(args: Array<String>) {
    print("Hello ${args[0]}")
}

Output :

Hello John
 
We could also add a size check on the args array using isEmpty() to check if any command line parameter was entered :

fun main(args: Array<String>) {
    if(args.isEmpty()){
        print("Please add some command line arguments")
        return
    }
    print("Hello ${args[0]}")
}

 
If multiple command line arguments are entered, we can access them in a loop like below :

fun main(args: Array<String>) {
    for(str in args)
        println("Hello ${str}")
}

 

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