org.apache.openjpa.lib.rop
Interface ResultObjectProvider

All Superinterfaces:

Closeable

All Known Subinterfaces:

PCResultObjectProvider

All Known Implementing Classes:

AbstractPCResultObjectProvider, GenericResultObjectProvider, InstanceResultObjectProvider, ListResultObjectProvider, MergedResultObjectProvider, OrderingMergedResultObjectProvider, PagingResultObjectProvider, RangeResultObjectProvider, SelectResultObjectProvider

public interface ResultObjectProvider
extends Closeable

Interface that allows lazy/custom instantiation of input objects. ResultList objects do not necessarily load in data all at once. Instead, they may lazily load objects as necessary. So, the lifespan of a ResultObjectProvider instance is related to how the application deals with processing the ResultList created with a given ResultObjectProvider instance.

Author:

Marc Prud'hommeaux, Patrick Linskey, Abe White

Method Summary

boolean	absolute(int pos) Move to the given 0-based position.
void	close() Free the resources associated with this provider.
Object	getResultObject() Instantiate the current result object.
void	handleCheckedException(Exception e) Any checked exceptions that are thrown will be passed to this method.
boolean	next() Advance the input to the next position.
void	open() Open the result.
void	reset() Reset this provider.
int	size() Return the number of items in the input, or Integer.MAX_VALUE if the size in unknown.
boolean	supportsRandomAccess() Return true if this provider supports random access.

Method Detail

supportsRandomAccess

boolean supportsRandomAccess()

Return true if this provider supports random access.

open

void open()
          throws Exception

Open the result. This will be called before next(), absolute(int), or size().

Throws:

Exception

getResultObject

Object getResultObject()
                       throws Exception

Instantiate the current result object. This method will only be called after next() or absolute(int).

Throws:

Exception

next

boolean next()
             throws Exception

Advance the input to the next position. Return true if there is more data; otherwise false.

Throws:

Exception

absolute

boolean absolute(int pos)
                 throws Exception

Move to the given 0-based position. This method is only called for providers that support random access. Return true if there is data at this position; otherwise false. This may be invoked in place of next().

Throws:

Exception

size

int size()
         throws Exception

Return the number of items in the input, or Integer.MAX_VALUE if the size in unknown.

Throws:

Exception

reset

void reset()
           throws Exception

Reset this provider. This is an optional operation. If supported, it should move the position of the provider to before the first element. Non-random-access providers may be able to support this method by re-acquiring all resources as if the result were just opened.

Throws:

Exception

close

void close()
           throws Exception

Free the resources associated with this provider.

Specified by:

close in interface Closeable

Throws:

Exception

handleCheckedException

void handleCheckedException(Exception e)

Any checked exceptions that are thrown will be passed to this method. The provider should re-throw the exception as an appropriate unchecked exception.