How to check a timeperiod is overlapping another time period in java

Question

How to check a time period is overlapping another time period in the same day.

For example,

1. 7:00AM to 10:30AM is overlapping 10:00AM to 11:30AM

Answer 1

If interval is opened (for example, some process is not finished yet) and end date might be null:

public static boolean isOverlapping(Date start1, Date end1, Date start2, Date end2)
{
    return
            ((null == end2) || start1.before(end2)) &&
            ((null == end1) || start2.before(end1)) ;
}