IntelliJ - 无法在混合（Java/Kotlin）模式下运行 Kotlin 类

Question

I am constantly getting the error (bottom right), but I have configured everything to run Kotlin/Java together. So, where is the missing bit which I cannot see.

UPDATE

A comment indicated that my pkg name was wrong, but it didn't matter regardless, as the below updated screenshot shows

Regards,

Answer 1

If you want to write the main function without any parameters, it has to be outside of the class like this:

package org.example

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

Note that in this case, the main function will be inside an artificial implicit class that is called like the containing file suffixed with Kt . This means, that in your example where you place the main function inside a file AppKt.kt , the resulting main class is called AppKtKt .

If you want to have the main function inside a class, you have to specify a parameter for the arguments. Also, it needs to be static, ie it has to be inside an object and must be annotated with @JvmStatic . This can be done by declaring an object:

object AppKt {
        @JvmStatic
        fun main(args: Array<String>) {
            println("Hello World!")
        }
}

Or you can put the main function inside the companion object of a class:

class AppKt {
    companion object {
        @JvmStatic
        fun main(args: Array<String>) {
            println("Hello World!")
        }
    }
}

Answer 2

在 Kotlin 中，您的 main 函数超出了任何类定义。