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public interface AggregateListener
An aggregate listener aggregates data produced by an ExpressionQuery.
| Method Summary | |
|---|---|
|  java.lang.Object | evaluate(java.util.Collection args,
         java.lang.Class[] argClasses,
         java.util.Collection candidates,
         StoreContext ctx)Return the value of this aggregate. | 
|  boolean | expectsArguments()Return whether this function expects to act on arguments. | 
|  java.lang.String | getTag()Return the tag that this listener listens for. | 
|  java.lang.Class | getType(java.lang.Class[] argClasses)Return the expected type of the result of this listener. | 
| Method Detail | 
|---|
java.lang.String getTag()
boolean expectsArguments()
count().
java.lang.Object evaluate(java.util.Collection args,
                          java.lang.Class[] argClasses,
                          java.util.Collection candidates,
                          StoreContext ctx)
args - for each candidate, the value of the arguments to
 the function; will be null if this aggregate does
 not expect an argument; if this function has
 multiple arguments, each element will be an arrayargClasses - the expected class of each argument elementcandidates - the candidate objects being evaluatedctx - the persistence context
UserException - if this aggregate does not 
 support in-memory operationjava.lang.Class getType(java.lang.Class[] argClasses)
argClasses - the expected classes of the argument, or null if
 no arguments| 
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