1. If someone asks to design a ROOM using Java,
   By keeping long term vision(meaning less future chnages) perspective

Which one can be chosen to design a ROOM, a class / abstract class/ interface?
And how ?

2. There is a csv log file with(1 million+ records) generated per day which contains, ip and time stamp.
   What solution can be used for finding:

   1. Count of distinct ip in each hour of a day

   Any Java solution can be used.
   Any big data solution if needed also could be used..