com.solarmetric.kodo.runtime.objectprovider
Interface ResultList

All Superinterfaces:

Collection, List, Serializable

All Known Subinterfaces:

CachingList, CustomResultList

All Known Implementing Classes:

CacheAwareQuery.CachedResultList, CollectionResultList, MergedResultList

public interface ResultList

extends List, Serializable

List interface that represents a potentially lazy ResultList instantiation. In accordance with section 14.6.7 of the JDO specification, iterators obtained from a Query or Extent that have been subsequently closed will return false for hasNext()

A ResultList will typically be instantiated from a factory, and will use a ResultObjectProvider for obtaining individual object data representations. For exmaple:

	java.sql.ResultSet rs = myStatement.executeQuery ("SELECT NAME FROM FOO");
	ResultList names = ResultListFactory.createResultList (threshold, rs,
		new ResultObjectProvider ()
		{
			public Object getResultObject (Object currentRow)
				throws Exception
			{
				return ((ResultSet) currentRow).getString ("NAME");
			}

			public boolean open (Object input) 
			{ 
				return ((ResultSet) input).next ();
			}

			public boolean advance (Object input)
			{ 
				return ((ResultSet) input).next ();
			}

			public void free (Object input) { }
		});
	

Depending on the data store support for scrolling result sets, the list that is returned may use lazy instantiation of the objects, and thus allow very large result sets to be obtained and manipulated.

Note that wrapping a ResultList in another Collection will always instantiate the entire set of elements contained in the ResultList. This may not always be desireable, since the list may be very large.

Since:

2.2.6

Method Summary

void	checkClosed() Check to see if this ResultList has been closed, and if so, throw a JDOUserException.
void	close() Close the list.
int	getInstantiatedCount() Returns the number of objects that are currently instantiated internally in this list.
boolean	isClosed() Returns true if the list has been closed.

Methods inherited from interface java.util.List

add, add, addAll, addAll, clear, contains, containsAll, equals, get, hashCode, indexOf, isEmpty, iterator, lastIndexOf, listIterator, listIterator, remove, remove, removeAll, retainAll, set, size, subList, toArray, toArray

Method Detail

close

public void close()
           throws JDOException

Close the list.

isClosed

public boolean isClosed()
                 throws JDOException

Returns true if the list has been closed.

checkClosed

public void checkClosed()
                 throws JDOException

Check to see if this ResultList has been closed, and if so, throw a JDOUserException.

getInstantiatedCount

public int getInstantiatedCount()

Returns the number of objects that are currently instantiated internally in this list.