positive
compareTo()
With all objects, compareTo() works
the way number comparisons work in ordinary arithmetic.
Here are a few rules.
Most of these are sensible if you think about numbers.
Say that A, B, and C are
Integers.
If A.compareTo(B) > 0 then B.compareTo(A) < 0.
If A.compareTo(B) > 0 and B.compareTo(C) > 0
then A.compareTo(C) > 0.
If A.compareTo(B) == 0
then A.compareTo(Z) and B.compareTo(Z) gives the
same result, no matter what Z is.
The classes that come with Java follow these rules.
If you write a class that implements Comparable,
you need to follow these rules.
This is not hard to do because
most sensible compareTo() methods will do this naturally.
Say that X.compareTo(Y)==0.
Is it then true that X.equals(Y)?