Sorting results using custom comparator

[Eshwar Prasad]

I have a requirement to sort the results of book retrieved from the database. The resultset contain 5 different columns like A B C D E. I implemented custom comparator to sort the values of column A as below

 
 class SortByColumnA implements Comparator{
        public int compare(Book one,Book two){
            return one.getBookName().compareTo(two.getBookName);
        }
   }
  

Sorting is happening perfectly. My question is if i need to provide user a option to sort other four columns, should i write 4 different classes implementing Comparator.

Also, as compareTo method is used here, do i need to override toString() , equals and hashCode method in my Book Class.

Please excuse me if it is very basic question. Kindly let me know your suggestions.

[Ernest Friedman-Hill]

You can write four different comparator classes, or you can use one comparator that does different things based on a constructor argument. Either way.

You really need to consider overriding equals() and hashCode() if you intend to put instances of a class into a Collection of any kind. This class seems to qualify, so I'd say "yes".