日時オブジェクトを比較するには

Java 2013/09/23

Signature:

// java.util.Date
int compareTo(Date another)

// java.util.Calendar
int compareTo(Calendar another)

// java.time.LocalDateTime (Java8)
int compareTo(LocalDateTime another)

// java.time.ZonedDateTime (Java8)
int compareTo(ZonedDateTime another)

Ruby 2013/08/08

require 'date'

a = DateTime.now
sleep 3
b = DateTime.now
p (a < b) # => true
p (b < a) # => false