info.archinnov.achilles.annotations

Annotation Type EmptyCollectionIfNull

@Retention(value=RUNTIME)
 @Target(value={FIELD,TYPE_USE})
 @Documented
public @interface EmptyCollectionIfNull

In Cassandra there is no difference between an empty collection/map and a null value for collection/map

In Java we do make the difference. This annotations allows mapping null values from Cassandra into empty collection & map.

Empty list will default to ArrayList.
Empty set will default to HashSet.
Empty map will default to HashMap.

 @Column
 @EmptyCollectionIfNull
 private List<String> friends
 

This annotation can be used for nested collections too:

 @Column
 private Tuple2<Integer,@EmptyCollectionIfNull List<String>> friends
 

See Also:

@EmptyCollectionIfNull