Intersecting overlapping intervals in Java

Question

I have an input set of date ranges that may overlap. Instead of combining these overlapping date ranges, I want to create new date ranges with adjusted dates, e.g.:

|---------------------–|
        |-----| 
            |--------------–|

should end up in:

|-------|---|-|--------|----|

Is there an efficient way to solve this with Java?

Thanks in advance!

UPDATE: I didn't mention my own approach in my first question, so here it is: I'd simply take the start and the end date of an interval and add it to a sorted set. Afterwards I'd iterate over the set and create new intervals based on re-ordered dates.

Answer 1

You could use Guava's Range support. Haven't used it with Date objects but it could work. Combined with RangeSet you could add all date ranges and then check if a Date is in the ranges, get the complete range, etc.

Answer 2

The basic idea:

• Split up each interval into start and end points
• Sort the points
• Iterate through the points and create the new intervals between all neighbouring points.
  Keep track of startIntervals - endIntervals and whenever this number is 0, there should be no interval in that range.