function - 如何从 Kotlin 中的函数返回具有不同类型(其中一个是数据类)的多个值？

Question

我有以下代码:

data class DMSAngle(var degree: Double, var minute: Double, var second: Double)

fun coordinateInverseCalculation(point1: Point3D, point2: Point3D){

    val horizontalDistance = sqrt(
        (point2.easting - point1.easting).pow(2.0) +
            (point2.northing - point1.northing).pow(2.0)
    )

    val heightDifference = point2.height - point1.height

    val slopePercent = (heightDifference / horizontalDistance) * 100

    val slopeDistance = sqrt(
        (point2.easting - point1.easting).pow(2.0) +
                (point2.northing - point1.northing).pow(2.0) +
                (point2.height - point1.height).pow(2.0)
    )

    val point12D = Point(easting = point1.easting, northing = point1.northing)
    val point22D = Point(easting = point2.easting, northing = point2.northing)
    val g12 = gizement(point12D, point22D)
    val g12DMS = decimalDegreesToDMS(g12)
}

我想要值 horizontalDistance: Double , heightDifference: Double , slopePercent: Double , slopeDistance: Double和 g12DMS: DMSAngle从函数中返回。我该怎么做？

我还需要一份全面的指南，以便了解如何从 Kotlin 中的函数返回多个值(具有或不具有不同类型)。 I have read about this听说过Pair , Triple , Array<Any> , List , interface , sealed class或 using the trick of creating data class to return and then destructing , 但似乎其中大部分用于返回 primitive data types不是data classes由于我是 Kotlin 的初学者，所以我有点困惑。您能否为我提供有关在 Kotlin 中返回多个值的全面解释，或者给我介绍一本书/任何其他有关此问题的全面文本？

Answer 1

Kotlin 不支持多种返回类型。执行此操作的惯用方法是声明一个 class 或 data class(我只是在编一个名字，更改以适应):

data class CoordinateInverse(
    val horizontalDistance: Double, 
    val heightDifference: Double, 
    val slopePercent: Double, 
    val slopeDistance: Double, 
    val g12DMS: DMSAngle
)

在你的函数结束时:

return CoordinateInverse(
    horizontalDistance,
    heightDifference,
    slopePercent,
    slopeDistance,
    g12DMS
)