1 online developer

https://developer.android.com/training/kotlinplayground 

2   use IntelliJ IDEA 

fun main(args: Array<String>) {
    println("Hello World!")

    // Try adding program arguments at Run/Debug configuration
    println("Program arguments: ${args.joinToString()}")
}

it works.

fun main(args: Array<String>) {
    val age  =40
    val Border ="%"
    println("Hello World!")

    // Try adding program arguments at Run/Debug configuration
   // println("Program arguments: ${args.joinToString()}")
    println("Hello world")
    println("You are already ${age}!")
    println("${age} is the very best age to celebrate!")
    printBorder(Border,23)
}
fun printBorder(Border:String, RepeatTimes:Int){
    repeat(RepeatTimes){
        print(Border)
    }
}

 

Add class

3 Android Studio

 if graddle is not installed, 

1. Right click on launcher icon of Android Studio
2. Click on "Run as administrator"

or fix at Graddle fixer

Problems：

   1. jdk  .  install the newest version, and set path variable. 

     Add the location of the bin folder of the JDK installation to the PATH variable in System Variables

 2 sdk lackness : download.

 3 Graddle can't run , even 　I have download and set its path ,but it doesn't work, only when the AS download it and fix.

4  haxm-7.7.0-setup.exe.   download it . and Enable BIOS  "Virtualization Technology" , then install it.

NOw , Ｉ　can build the project.

 

4 Simulate on 夜神

 Sometimes we can not use the simulator of AS, so we can use third party software.

And if we can't enable VT-X, you can refer

https://answers.microsoft.com/en-us/insider/forum/insider_wintp-insider_web/virtualization-technology-not-working-on-windows/6d790614-58de-4b8b-9ecd-249f2ab40ff8