Comparing ENUMs in Java 6

Question

I am trying to find best way to compare Enums in Java 6.

Say, I have an ENUM of Ticket Types which can be associated with a Traveler. If there is a list of travelers, I would like to know the traveler with the highest class of travel.

I can iterate thru the list of travelers, create a Set of unique TicketTypes, Convert to List, Sort them, Return the last element as the highest. I would like to know if there is a better way to do this?

 public enum TicketType {
    ECONOMY_NON_REF(1,"Economy Class, Non-Refundable"),
    ECONOMY_REF(2,"Economy Full Fare Refundable"),
    BUSINESS(3,"Business Class"),
    FIRST_CLASS(4,"First Class, Top of the world");

    private String code;
    private String description;
}

public class Traveler {
    private TicketType ticketType;
            public Traveler(TicketType ticketType) {
                this.ticketType = ticketType;
            }
}

@Test
public testCompareEnums{
    List<Traveler> travelersGroup1 = new ArrayList<Travelers>();
    travelersGroup1.add(new Traveler(TicketType.ECONOMY_REF));
    travelersGroup1.add(new Traveler(TicketType.BUSINESS));
    travelersGroup1.add(new Traveler(TicketType.ECONOMY_REF));
    travelersGroup1.add(new Traveler(TicketType.ECONOMY_NON_REF));

    //What is the best way to find the highest class passenger in travelersGroup1.
    assertEquals(TicketType.BUSINESS, getHighestClassTravler(travelersGroup1));

    List<Traveler> travelersGroup2 = new ArrayList<Travelers>();
    travelersGroup2.add(new Traveler(TicketType.ECONOMY_REF));
    travelersGroup2.add(new Traveler(TicketType.ECONOMY_NON_REF));
    travelersGroup2.add(new Traveler(TicketType.ECONOMY_REF));
    travelersGroup2.add(new Traveler(TicketType.ECONOMY_NON_REF));
    assertEquals(TicketType.ECONOMY_REF, getHighestClassTravler(travelersGroup2));
}

    private CredentialType getHighestClassTraveler(List travelers){
            Set uniqueTicketTypeSet = new HashSet();
            for (Traveler t: travelers) {
                     uniqueTicketTypeSet.add(t.getTicketType());
               }
             List<TicketType> uniqueTicketTypes = new ArrayList<TicketType>(uniqueTicketTypeSet);   
             Collections.sort(uniqueTicketTypes);
             return uniqueTicketTypes.get(uniqueTicketTypes.size()-1);
     }

What have you tried? Do you have a working implementation of getHighestClassTravler() ? — GreyBeardedGeek, Oct 27 '12 at 02:16
`private CredentialType getHighestClassTraveler(List travelers){ Set uniqueTicketTypeSet = new HashSet(); for (Traveler t: travelers) { uniqueTicketTypeSet.add(t.getTicketType()); } List uniqueTicketTypes = new ArrayList(uniqueTicketTypeSet); Collections.sort(uniqueTicketTypes); return uniqueTicketTypes.get(uniqueTicketTypes.size()-1); }` — aprajitha, Oct 27 '12 at 02:20

score 1 · Accepted Answer · answered Oct 27 '12 at 05:09

1

There's a lot of problems with the code that you posted (it won't compile without fixing a lot of errors), but the easiest way is to make Traveler implement the Comparable interface, like so:

  public int compareTo(Traveler other) {
       return this.getTicketType().compareTo(other.getTicketType());
  }

Then to find the the Traveler with the highest TicketType, you can simply do:

 Collections.max(travelers);

answered Oct 27 '12 at 05:09

GreyBeardedGeek

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Thanks @GreyBeardedGeek. I had typed the code from a tablet and did not actually compile. Since Enums already implement comparable interface, I used Collections.max() on a set of unique TicketTypes. – aprajitha Oct 29 '12 at 03:17
Yes, that gets you the max TicketType, if that's all you need. Making Traveler implement Comparable allows you to find the Traveler who has the "max TicketType". If you don't need that, then the max of the ticket types is indeed all you need. – GreyBeardedGeek Oct 29 '12 at 17:43

Comparing ENUMs in Java 6

1 Answers1