Java sorting - comparable v comparator

java.lang.Comparable	java.util.Comparator
int objOne.compareTO(objTwo) – A Comparable interfaced class must contain a method called compareTo to compare two objects (one being the object on which it is called and the other being passed as a paramater)	int compare(objOne, objTwo) – A Comparator is a class in its own right, which implements the Comparator interface; that means it must contain a method called compare (two objects as parameters)
Return Values - negative – if objOne < objTwo zero – if objOne = objTwo positive – if objOne > objTwo	Return Value - same as Comparable
Only one sort sequence can be created	Many sort sequences can be created
You must modify the class whose instances you want to sort	You build a separate class from the class whose instances you want to sort
Implemented frequently in the API by : String, Wrapper Classes, Date, Calendar	Meant to be implemented to sort instances of third-party classes
If you want to sort a collection using its comparable interface, you simply call the static Collections.sort method on it … so if we had an ArrayList called Animal which implemented Comparable, we could write: Collections.sort(Animal);	To sort a collection using a Comparator class, you need to pass an extra parameter into the Collections.sortmethod – that parameter being an instance of a Comparator object. Thus: Collections.sort(Animal, new ByBreed());