什么是的语法使用时数comparations在当的声明

Question 1

我有这个代号：

      statisticsSettings = when (ScreenHandler.convertPixelsToDp(width, context).toInt()){
            320 -> StatisticsSettings.SMALL_PHONE
            480 -> StatisticsSettings.LARGE_PHONE
            600 -> StatisticsSettings.SMALL_TABLET
            720 -> StatisticsSettings.LARGE_TABLET
            else -> throw IllegalArgumentException("Cannot compute dp")
        }

我想知道如果我可以让情况下的 when 声明与比较，而不是一个整数。事情是这样的：

      statisticsSettings = when (ScreenHandler.convertPixelsToDp(width, context).toInt()){
            ScreenHandler.convertPixelsToDp(width, context).toInt()) < 320 -> StatisticsSettings.SMALL_PHONE
            ScreenHandler.convertPixelsToDp(width, context).toInt()) < 480 -> StatisticsSettings.LARGE_PHONE
            ScreenHandler.convertPixelsToDp(width, context).toInt()) < 600 -> StatisticsSettings.SMALL_TABLET
            ScreenHandler.convertPixelsToDp(width, context).toInt()) < 720 -> StatisticsSettings.LARGE_TABLET
            else -> throw IllegalArgumentException("Cannot compute dp")
        }

Question 2

使用范围：

val statisticsSettings = when (ScreenHandler.convertPixelsToDp(width, context).toInt()){
  in 0..320 -> StatisticsSettings.SMALL_PHONE
  in 321..480 -> StatisticsSettings.LARGE_PHONE
  in 481..600 -> StatisticsSettings.SMALL_TABLET
  in 601..720 -> StatisticsSettings.LARGE_TABLET
  else -> throw IllegalArgumentException("Cannot compute dp")
}

或者你可以使用枚举constants:

enum class StatisticsSettings(val intRange: IntRange) {
  SMALL_PHONE(0..320),
  LARGE_PHONE(321..480),
  SMALL_TABLET(481..600),
  LARGE_TABLET(601..720)
}

val intRange = ScreenHandler.convertPixelsToDp(width, context).toInt()

val statisticsSettings = StatisticsSettings.values().find { intRange in it.intRange }

这具有的优点是，范围是"约束"enum本身。如果你改变了这些价值观，你不必改变它们关于可能的多个地点在你的代码。

编辑：交换来自过滤，以找到 (由于@ArpitShukla，参见下面的评论)

lukas.j · Answer 1 · 2021-11-24T08:43:33

使用范围：

val statisticsSettings = when (ScreenHandler.convertPixelsToDp(width, context).toInt()){
  in 0..320 -> StatisticsSettings.SMALL_PHONE
  in 321..480 -> StatisticsSettings.LARGE_PHONE
  in 481..600 -> StatisticsSettings.SMALL_TABLET
  in 601..720 -> StatisticsSettings.LARGE_TABLET
  else -> throw IllegalArgumentException("Cannot compute dp")
}

或者你可以使用枚举constants:

enum class StatisticsSettings(val intRange: IntRange) {
  SMALL_PHONE(0..320),
  LARGE_PHONE(321..480),
  SMALL_TABLET(481..600),
  LARGE_TABLET(601..720)
}

val intRange = ScreenHandler.convertPixelsToDp(width, context).toInt()

val statisticsSettings = StatisticsSettings.values().find { intRange in it.intRange }

这具有的优点是，范围是"约束"enum本身。如果你改变了这些价值观，你不必改变它们关于可能的多个地点在你的代码。

编辑：交换来自过滤，以找到 (由于@ArpitShukla，参见下面的评论)

你可以替换 filter 与 find. 这将使更多的意义在这里。

什么是的语法使用时数comparations在当的声明

的问题

最好的答案

其他语言

此页面有其他语言版本

受欢迎的此类别

流行的问题，在这个类别