Comparator Best Practice

Question

I am looking for some suggestions on how to sort a Collection of Objects multiple ways.
I have the following Class:
public class User {
private String firstName;
private Date dob;
private String lastName;
}And I want to sort it in different ways, by firstName or by dob etc.
My idea after doing some reading is to provide a class that holds the different sort types
import java.util.*;
public class UserSortTypes {
    static final Comparator<User> FIRST_NAME_ORDER = new Comparator<User>() {
        public int compare(User u1, User u2) {
            return u1.getFirstName().compareTo(u2.getFirstName());
static final Comparator<User> DOB_ORDER = new Comparator<User>() {
        public int compare(User u1, User u2) {
            return u1.getDOB().compareTo(u2.getDOB());
}and then use that class when sorting etc.
What is the best practice for sorting a collection multiple ways?
Thank you,
Al

Answer 1

I'd do something like this, which is the same way you did it,...
public class UserComparator implements Comparator<User> {
     private SortField field;
     private SortOrder sortOrder = SortOrder.ASCENDING;
     @Override
     public int compare(User o1, User o2) {
          int retVal = 0;
          // null-check...
          switch (field) {
          case FIRSTNAME:
               retVal = o1.getFirstName().compareTo(o2.getFirstName());
          case LASTNAME:
               retVal = o1.getLastName().compareTo(o2.getLastName());
          if(sortOrder == SortOrder.DESCENDING){
               retVal *= -1;
          return retVal;
     public enum SortField {
          FIRSTNAME, LASTNAME;
     public enum SortOrder {
          ASCENDING, DESCENDING;
}Best practice? I dunno,...
For our presentation logic, we carry it to excess... we use one Comparator for sorting a List, displayed to the browser. Using it for for all types.
... 1.4 ...
public class BeanComparator implements Comparator {
     private String property = null;
     private boolean ascending = true;
     public int compare(Object o1, Object o2) {
          int result = 0;
          Object value1 = this.getProperty(o1, property);
          Object value2 = this.getProperty(o2, property);
          // null checks,...
          if (value1 instanceof String) {
               String s1 = (String) value1;
               String s2 = (String) value2;
               result = s1.compareToIgnoreCase(s2);
          } else if (value1 instanceof Date) {
               Date d1 = (Date) value1;
               Date d2 = (Date) value2;
               result = d1.compareTo(d2);
                // and other types,..
          if (!ascending) {
               result = result * -1;
          return result;
     private Object getProperty(Object obj, String property) {
          // get property using reflection,...
}regards
slowfly