Defining enum with abstract method which returns a generic type

Question

Is it possible to define an abstract method which returns an geneic type like below? Thanks
public enum Type{
     A{
          public List<Integer> getData(){}
     B{
          public Set<String> getData{}
     abstract<T> T getData();
}

Answer 1

vulee wrote:
Why not?
List<Integer> lst = Type.A.getData();Wonder, which compiler you use. Can't be Java6:
# javac Enums.java
Enums.java:23: incompatible types
found   : java.util.Collection<capture#376 of ?>
required: java.util.List<java.lang.Integer>
                List<Integer> data = Type.A.getData();
                                                   ^
1 errorEdit: Unless you do it the generic way as you proposed, which actually is a phoney. Because of the T being a generic method parameter, the compiler will infer it from the type of the variable it gets assigned to. Hence, both of the following will compile:
List<Integer> lst = Type.A.getData();
Set<String> lst2 = Type.A.getData(); // Runtime exceptionActually, javac is telling you that giving warnings on the enum constants redefined method return types.
Edited by: stefan.schulz on Sep 10, 2008 11:38 PM