Sprting a HashSet by propert

Question

Hi all,
I want to sort a Set by a property that is in the objects of the set. The property is a String. I searched around the net but could find anything that would relate to my problem.
Greets

Answer 1

I turned it into a list...
But cant get the Collection.Sort good
this is the code:
package nl.wag.webarm.utils;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import nl.wag.webarm.model.FactuurOnderdeel;
public class FactuurUtils {
     public static void createFactuur (Set onderdelen){
          if (onderdelen != null){
               List onderdelenlijst = new ArrayList();
               Iterator it = onderdelen.iterator();
               while ( it.hasNext()){
                         FactuurOnderdeel fo = (FactuurOnderdeel) it.next();
                         onderdelenlijst.add(fo);
               Collections.sort(onderdelenlijst,new OdComparator()); // this is where eclipse shows the warnings.. warnings are on the bottom of this post..
      public class OdComparator implements Comparator{
               public int compare(Object arg0, Object arg1) {
                    String  s1 = ((FactuurOnderdeel) arg0).getId();
                    String  s2 = ((FactuurOnderdeel) arg1).getId();
                    return s1.compareTo(s2);
}And this is the warings eclipse gives:
Multiple markers at this line
     - Type safety: The expression of type FactuurUtils.OdComparator needs unchecked
     conversion to conform to Comparator<? super T>
     - No enclosing instance of type FactuurUtils is accessible. Must qualify the allocation with
     an enclosing instance of type FactuurUtils (e.g. x.new A() where x is an instance of FactuurUtils).
     - Type safety: Unchecked invocation sort(List, Comparator) of the generic method sort
     (List<T>, Comparator<? super T>) of type Collections
     - Type safety: The expression of type List needs unchecked conversion to conform to
     List<T>