Efficent collection to associate a key with multiple value Objects [duplicate]

Answer 1

How about Plain Old Java Object approach -

public class CutomerFacilityDetail{
   List<CustomerVO> customvoList;
   List<FacilityInfo> facilityInfoList;
   ...<getter & setter method>
}

Now create map -Map<Long,List<CutomerFacilityDetail>>

Answer 2

Have a look at Apache Commons Multimap - it seems to be what you're after:

MultiMap mhm = new MultiHashMap();
mhm.put(key, "A");
mhm.put(key, "B");
mhm.put(key, "C");
Collection coll = (Collection) mhm.get(key);

Alternatively, you can just stick a collection of any kind into a regular map, e.g:

Map<Key, Set<Value>> myMap;