使用HQL时ClassCastException

Question

See the following mapping

public class SomeClass {

    private Integer someField;

}

When i call the following query

select someField, count(*) from SomeClass inner join OtherClass... group by ...

And i proccess the query as follows

Map<Integer, Integer> result = new HashMap<Integer, Integer>();

List<Object> objectList = query.list();
for(Object object: objectList) {
    Object [] objectArray = (Object []) object;

    result.put((Integer) objectArray[0], (Integer) objectArray[1]);
}

I get ClassCastException: can not convert Long to Integer

Question: what should i do to retrieve the values returned by the HQL as Integer instead of Long ????

Answer 1

If you don't know which it will be ( Integer or Long ), you can cast to Number and call intValue() or longValue() . This way an Integer or a Long will work.

result.put((Integer) objectArray[0], ((Number) objectArray[1]).intValue() );

The small downside with this is you end up unboxing the Number and reboxing it to put in the map.

Answer 2

I guess the second column in the result - ie count(*) returns Long . You can get its int value by ((Long) objectArray[1]).intValue()

Or (as suggested), better change your map to Map<Integer, Long> , so that no information is eventually lost.