What is the syntax when using number comparations in when statement-CodePudding

I have this code:

      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")
        }

and I was wondering if I could make cases of the when statement with a comparator instead of an integer. Something like this:

      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")
        }

CodePudding user response：

Use ranges:

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")
}

Or you could use enum 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 }

This has the advantage that the ranges are "bound" to the enum itself. If you ever change these values, you don't have to change them on possibly multiple locations in your code.

Edit: switched from filter to find (thanks to @ArpitShukla, see comment below)