Numerically stable average of java.util.Dates

Question

I've got a bunch of Dates and I want to find their average.

• How many Dates within 100 years of now can I sum before I run into overflow problems? Any gotchas?
• What's the best way to calculate the average, avoiding overflow problems?

Answer 1

System.out.println(Long.MAX_VALUE / System.currentTimeMillis());

Output:

6892653

I think this answers both of your questions. You can also divide each epoch value by 1000*60*60*24, but given the size of that raw quotient, even that's probably overkill.