“ In”代码在Android Studio Kotlin中无法识别

Question

我已经复制了教程中的一些代码，但是当我到达这里时：

azimuth = Math.round(azimuth.toFloat())
    compass_image.rotation = (-azimuth).toFloat()

    val where = when(azimuth){
        in 281...348 -> "NW"
        in 281...348 -> "NW"
        in 281...348 -> "NW"
        in 281...348 -> "NW"
        in 281...348 -> "NW"
        in 281...348 -> "NW"
        in 281...348 -> "NW"
        else -> "N"
    }

    view_degree.text = "$azimuth° $where"

Android Studio无法识别命令“ in” ...怎么来的？在此先感谢

Answer 1

这是因为您必须使用两个点而不是三个点来表示范围。此外，所有这些情况都是相同的，因此重复它们是无用的。

val where = when(azimuth){
    in 281..348 -> "NW"
    else -> "N"
}

此处的附加信息：kotlinlang.org/docs/reference/ranges.html