enum compareTo()

[Wojtek]

I have the following code:
----------------------------------
public enum Type implements Comparable<Type>
{
TYPE_A("a"),TYPE_B("b");

private String sortOrder;

private Type( String sort )
{
sortOrder=sort;
}

private String getSort()
{
return sortOrder;
}

@Override
public int compareTo(Type type)
{
return getSort().compareTo(type.getSort());
}
}
----------------------------------

However it seems that enum has a compareTo method which is final, so I
cannot implement my own sort order when I use the enum as a key in a
TreeMap.

Why is this?

 

[Mark Space]

I have the following code:

However it seems that enum has a compareTo method which is final, so I

Huh. Yet when I look at the Java doc, compareTo() is not declared
final. Why is that?


Maybe if you read the Java doc, you'd notice that the base enum type
already implements Comparable. I haven't tried to override a compareTo
method, but it might work if you just got rid of the "implements
Comparable<Type>" part of your enum declaration....

 

[Wojtek]

Mark Space wrote :

Huh. Yet when I look at the Java doc, compareTo() is not declared final.
Why is that?


Maybe if you read the Java doc, you'd notice that the base enum type already
implements Comparable. I haven't tried to override a compareTo method, but
it might work if you just got rid of the "implements Comparable<Type>" part
of your enum declaration....

Same error.

 

[Wojtek]

Mark Space wrote :

Huh. Yet when I look at the Java doc, compareTo() is not declared final.

Yes it is "final" for the class Enum:

http://java.sun.com/javase/6/docs/api/java/lang/Enum.html#compareTo(E)

 

[Joshua Cranmer]

However it seems that enum has a compareTo method which is final, so I
cannot implement my own sort order when I use the enum as a key in a
TreeMap.

Why is this?

Well, you can always override the compareTo method on a TreeMap by
passing in your own Comparator...

 

[Mark Space]

Mark Space wrote :

Yes it is "final" for the class Enum:

http://java.sun.com/javase/6/docs/api/java/lang/Enum.html#compareTo(E)

Ah, it's not marked final on the method summary list above.
Interesting. Well sorry about that....

 

[Wojtek]

Joshua Cranmer wrote :

Well, you can always override the compareTo method on a TreeMap by passing in
your own Comparator...

Ok, that works.

Now I feel like a rebel