在 kotlin 中输入一个列表作为函数的默认值

Question

I defined the function "fireAtTarget" in kotlin. As an argument, I need to insert a default value for the list. How could I achieve this?

fun fireAtTarget(massKg: Double=80.2, eachGunAmmo: List<Int>=listOf(2, 3): Boolean{

       //function body

  }

I expect to call fireAtTarget() with no arguments getting 0 error messages

Answer 1

There is a syntax error in your code: you simply forgot to close bracket in function parameters declaration:

fun fireAtTarget(massKg: Double=80.2, eachGunAmmo: List<Int> = listOf(2,3)): Boolean {
       //function body
}

Answer 2

I was experiencing this problem (IntelliJ reports an error Expecting a top level declaration ) with the following code:

fun foo(value: List<Int>=listOf(1,2)) { }

The problem was solved by inserting whitespace space before the equals List<Int>*space*=listOf

fun foo(value: List<Int> = listOf(1,2)) { }

The Kotlin language has a >= operator that the original may be confused with.

See: https://kotlinlang.org/docs/reference/operator-overloading.html#comparison

Answer 3

您可以创建一个具有默认值的列表，如下所示：

val defaultValueList = List<String>(10) {"I am default"}