compareTo
public final int compareTo(E o)
Compares this enum with the specified object for order. Returns a negative integer, zero, or a positive integer as this object is less than, equal to, or greater than the specified object. Enum constants are only comparable to other enum constants of the same enum type. The natural order implemented by this method is the order in which the constants are declared.
Specified by:
compareTo in interface Comparable<E extends Enum<E>>
Parameters:
o - the object to be compared.
Returns:
a negative integer, zero, or a positive integer as this object is less than, equal to, or greater than the specified object.
From:
http://java.sun.com/javase/6/docs/api/java/lang/Enum.html