Google Guava: Range with LocalDate

This afternoon I was working on implementing a user story with (JodaTime) LocalDate ranges. The problem? I needed to represent a lot of periods, in days. The thing I needed to check: Is a certain LocalDate contained in this period.

First I started looking at JodaTime itself, it has support for Interval(s). But there is a ‘problem’, Interval is based around ReadableInstants, and LocalDate is a ReadablePartial, not a ReadableInstant! So to make my code work I had to do the following:

    // Use two LocalDate instances to create an Interval (the JodaTime way)
    private Interval createInterval(LocalDate fromDate, LocalDate toDate) {
        DateTime fromDateTime = fromDate.toDateTimeAtStartOfDay();
        DateTime toDateTime = toDate.toDateTimeAtStartOfDay();
        return new Interval(fromDateTime, toDateTime);
    }

    // Now to check an interval I needed to call:
    createdInterval.contains(inputDate.toDateTimeAtStartOfDay());

It works, sure, but the conversion to ReadableInstant with toDateTimeAtStartOfDay kind of bugged me. But luckely Google Guava has something to make the code much cleaner: Ranges

Using Range made the code much smaller and easier to read:

    // Use two LocalDate instances to create an Range (the Google Guava way)
    private Range<LocalDate> createRange(LocalDate fromDate, LocalDate toDate) {
        return Range.closedOpen(fromDate, toDate);
    }

    // To check:
    createRange.contains(inputDate);

I really love using Google Guava, it provides solutions for a lot of common programming challenges. Not only that, their API is very very clean and skillfully designed. The use of open/closed in Range.java is very handy and makes it easy to think about corner cases.