Simple extending enum question...

[Sharon whipple]

Hi ranchers

I am extending emum and trying to cast it to the extending enum:

public class FooEnum implements Enum {
                      //do something with the constructor parameter
                      public static final FooEnum EVALUE = new FooEnum(_String);


public BarEnum extends FooEmun{
         BarEnum(String _string){
                 super(_string);
            }
} 


//ClassCastException
BarEnum b = BarEnum.EVALUE;

I am getting Class cast because EVALUE is FooEnum and not BarEnum
What is the correct way/pattern for such case?

[Wouter Oet]

I'm not sure what you're trying to accomplish. If you want to use an enum you should not create a class but an enum. The Oracle Java Tutorial section about enums can be found here.

[Sharon whipple]

Wouter Oet wrote:I'm not sure what you're trying to accomplish. If you want to use an enum you should not create a class but an enum. The Oracle Java Tutorial section about enums can be found here.

I m trying to inherit legacy class implementing enum and adding functionality..

[Wouter Oet]

Then I would not use the name Enum because it will confuse people with the enum functionality of the java language.
But about your problem. I'll give you a hint by rename it:

public class Animal implements Enum {
                      //do something with the constructor parameter
                      public static final Animal EVALUE = new Animal(_String);


public Dog extends Animal{
         Dog(String _string){
                 super(_string);
            }
} 


//ClassCastException
Dog b = Dog.EVALUE;

[Sharon whipple]

Unfortunately Animal cannot be changed because it is used by other APIs, adding values to Animal is impossible.


I didn't get it, you will still get ClassCastException on Dog b = Dog.EVALUE;
What is the difference?

[Wouter Oet]

You're trying to use a Dog reference on an Animal.

[Sharon whipple]

I found a solution I can live with:

Existing enum will stay intact:

public class FooEnum implements Enum {  
                      //do something with the constructor parameter  
                      public static final FooEnum EVALUE = new FooEnum(_String);  

Inheriting class will add new functionality as so:

 public BarEnum extends FooEmun{  

         public static final FooEnum NEW_VALUE = new FooEnum(_String);

         BarEnum(String _string){  
                 super(_string);  
            }  
}

//No ClassCastException
FooEnum b = BarEnum.NEW_VALUE;