The Java class library has a class named DateTime. DateTime has this method:
int daysBetween(DateTime other)
which returns the number of days between this and the parameter. It doesn't have a method
int secondsBetween(DateTime other)
which I happen to need. Is there a class which is similar to DateTime but has such a method?
If you're using Joda (which may be coming as jsr 310 in JDK 7, separate open source api until then) then there is a Seconds class with a secondsBetween method.
Here's the javadoc link: http://joda-time.sourceforge.net/api-release/org/joda/time/Seconds.html#secondsBetween(org.joda.time.ReadableInstant,%20org.joda.time.ReadableInstant)
Just a pointer: If you're calculating the difference between two java.util.Date the approach of subtracting both dates and dividing it by 1000 is reasonable, but take special care if you get your java.util.Date reference from a Calendar object. If you do so, you need to take account of daylight savings of your TimeZone since one of the dates you're using might take place on a DST period.
That is explained on Prasoon's link, I recommend taking some time to read it.