Java Comparable vs Comparator

Question

Possible Duplicates    difference between compare   and compareTo     Java  What is the difference between implementing Comparable and Comparator        What are the keys differences between Comparable and Comparator     and which is preferred over the other in what scenarios     Thanks  Updated - GOOD LINK WITH EXAMPLE    http   www digizol com 2008 07 java-sorting-comparator-vs-comparable html

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Comparator provides a way for you to provide custom comparison logic for types that you have no control over   Comparable allows you to specify how objects that you are implementing get compared   Obviously  if you don t have control over a class  or you want to provide multiple ways to compare objects that you do have control over  then use Comparator   Otherwise you can use Comparable

User · Answer

When your class implements Comparable  the compareTo method of the class is defining the  natural  ordering of that object   That method is contractually obligated  though not demanded  to be in line with other methods on that object  such as a 0 should always be returned for objects when the  equals   comparisons return true   A Comparator is its own definition of how to compare two objects  and can be used to compare objects in a way that might not align with the natural ordering   For example  Strings are generally compared alphabetically   Thus the  a  compareTo  b   would use alphabetical comparisons   If you wanted to compare Strings on length  you would need to write a custom comparator   In short  there isn t much difference  They are both ends to similar means   In general implement comparable for natural order   natural order definition is obviously open to interpretation   and write a comparator for other sorting or comparison needs

[java] Java : Comparable vs Comparator

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