Kotlin has closed ranges which are useful for many things. When you want to check if two date ranges overlap you can use the beneath for an extension function overlap to calculate if two ranges overlap.

typealias DateRange = ClosedRange<LocalDate>

fun ClosedRange<LocalDate>.overlap(dateRange: ClosedRange<LocalDate>): Boolean =
        dateRange.start <= this.endInclusive && dateRange.endInclusive >= this.start

Now you can specifiy a date range via val dateRange: DateRange = LocalDate.now()..LocalDate.now().plusDays(1) for example.