以编程方式从可绘制对象中获取图像并在 Android Kotlin 中加载一周中的每一天（白天或晚上）

Question

我有一个 Kotlin 代码可以在白天和晚上显示图像（imageday.png 和 imagenight.png） 这是代码：

private fun getBackgroundImageByTime(time: LocalTime): Int =
            when (time.hour) {
                in 6..18 -> R.drawable.imageday             
                else -> R.drawable.imagenight
            }

现在我正在尝试在上述时间按一周中的几天加载图像。

我的图像是：monday_imageday、monday_imagenight、tuesday_imageday、tuesday_imagenight 等... 如何以编程方式从可绘制文件夹加载这些图像取决于今天的日期。 如果今天是星期二，则应分别加载 imageday 和 imagenight。

我在这里感到震惊，请有人帮忙。

Answer 1

如果你的最小SDK是26，你可以使用

LocalDateTime

。

val dateTime = LocalDateTime.now()
val dayOfWeek = dateTime.dayOfWeek
val hour = dateTime.hour

val image = when(dayOfWeek) {
    DayOfWeek.MONDAY -> if (hour in 6..18) R.drawable.monday_imageday else R.drawable.monday_imagenight
    DayOfWeek.TUESDAY -> if (hour in 6..18) R.drawable.tuesday_imageday else R.drawable.tuesday_imagenight
    DayOfWeek.WEDNESDAY -> if (hour in 6..18) R.drawable.wednesday_imageday else R.drawable.wednesday_imagenight
    DayOfWeek.THURSDAY -> if (hour in 6..18) R.drawable.thursday_imageday else R.drawable.thursday_imagenight
    DayOfWeek.FRIDAY -> if (hour in 6..18) R.drawable.friday_imageday else R.drawable.friday_imagenight
    DayOfWeek.SATURDAY -> if (hour in 6..18) R.drawable.saturday_imageday else R.drawable.saturday_imagenight
    DayOfWeek.SUNDAY -> if (hour in 6..18) R.drawable.sunday_imageday else R.drawable.sunday_imagenight
}

如果您的最低 SDK 低于 26，您可以使用

Calendar

实现向后兼容。

val calendar = Calendar.getInstance()
val dayOfWeek = calendar.get(Calendar.DAY_OF_WEEK)
val hour = calendar.get(Calendar.HOUR_OF_DAY)

val image = when(dayOfWeek) {
    1 -> if (hour in 6..18) R.drawable.monday_imageday else R.drawable.monday_imagenight
    2 -> if (hour in 6..18) R.drawable.tuesday_imageday else R.drawable.tuesday_imagenight
    3 -> if (hour in 6..18) R.drawable.wednesday_imageday else R.drawable.wednesday_imagenight
    4 -> if (hour in 6..18) R.drawable.thursday_imageday else R.drawable.thursday_imagenight
    5 -> if (hour in 6..18) R.drawable.friday_imageday else R.drawable.friday_imagenight
    6 -> if (hour in 6..18) R.drawable.saturday_imageday else R.drawable.saturday_imagenight
    7 -> if (hour in 6..18) R.drawable.sunday_imageday else R.drawable.sunday_imagenight
}