如何在Kotlin中将vararg传递给varag函数或构造函数? [英] How to Pass vararg to a varag function or constructor in Kotlin?

问题描述

Kotlin不允许我的子类将vararg传递给我的超类构造函数 这是我的Operation课:

Kotlin does not allow my subclass to pass vararg to my super class constuctor Here is my Operation class:

package br.com.xp.operation

import java.util.ArrayList

abstract class Operation(vararg values: Value) : Value {
    protected var values: MutableList<Value> = ArrayList()

    internal abstract val operator: String
}

这是我的SubtractionOperation类:

and here is my SubtractionOperation class:

package br.com.xp.operation

class SubtractionOperation private constructor(vararg values: Value) : Operation(values) {
    override val operator: String
        get() = "-"
}

编译说:

类型不匹配找到所需值数组

Type mismatch Required Value found Array

任何人都可以解释为什么这不可能吗?

Can anyone explain why this is not possible?

推荐答案

来自文档:

在函数中，类型为T的vararg-参数作为T的数组可见.

Inside a function a vararg-parameter of type T is visible as an array of T.

因此，在SubtractionOperation构造函数中，values实际上是Array<Value>.您需要使用 spread 运算符(*)来转发这些消息:

So in the SubtractionOperation constructor, values is really an Array<Value>. You need to use the spread operator (*) to forward these on:

class SubtractionOperation private constructor(vararg values: Value) : Operation(*values) ...

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