T - Enum type representing the possible operations 'results'public interface OperationObserver<T extends java.lang.Enum<T>>
Operations must have an associated enum type that represents their possible outcomes. An example of such an enum type would be:
 enum PlaneFlight {
   LAND, CRASH;
 }
 | Modifier and Type | Method and Description | 
|---|---|
| void | begin()Called immediately prior to the operation beginning. | 
| void | end(T result)Called immediately after the operation completes with no interesting parameters, and with the same thread the called { begin()} before. |