org.apache.openjpa.lib.rop
Class RangeResultObjectProvider

java.lang.Object
  org.apache.openjpa.lib.rop.RangeResultObjectProvider

All Implemented Interfaces:

ResultObjectProvider, Closeable

public class RangeResultObjectProvider
extends Object
implements ResultObjectProvider

Prevents a view of a given range of indices from the delegate result object provider.

Author:

Abe White

Constructor Summary

RangeResultObjectProvider(ResultObjectProvider delegate, long startIdx, long endIdx)
Constructor.

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.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

RangeResultObjectProvider

public RangeResultObjectProvider(ResultObjectProvider delegate,
                                 long startIdx,
                                 long endIdx)

Constructor. Because this is a wrapper around some delegate, and result object providers work with int indexes, neither the start or end index can be greater than Integer.MAX_VALUE(with the exception of Long.MAX_VALUE, which is used to indicate no limit).

Parameters:

delegate - the result object provider to delegate to

startIdx - 0-based inclusive start index of the range to present; must be < Integer.MAX_VALUE

endIdx - 0-based exclusive end index of the range to present; must be < Integer.MAX_VALUE, or Long.MAX_VALUE for no limit

Method Detail

supportsRandomAccess

public boolean supportsRandomAccess()

Description copied from interface: ResultObjectProvider

Return true if this provider supports random access.

Specified by:

supportsRandomAccess in interface ResultObjectProvider

open

public void open()
          throws Exception

Description copied from interface: ResultObjectProvider

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

Specified by:

open in interface ResultObjectProvider

Throws:

Exception

getResultObject

public Object getResultObject()
                       throws Exception

Description copied from interface: ResultObjectProvider

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

Specified by:

getResultObject in interface ResultObjectProvider

Throws:

Exception

next

public boolean next()
             throws Exception

Description copied from interface: ResultObjectProvider

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

Specified by:

next in interface ResultObjectProvider

Throws:

Exception

absolute

public boolean absolute(int pos)
                 throws Exception

Description copied from interface: ResultObjectProvider

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 ResultObjectProvider.next().

Specified by:

absolute in interface ResultObjectProvider

Throws:

Exception

size

public int size()
         throws Exception

Description copied from interface: ResultObjectProvider

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

Specified by:

size in interface ResultObjectProvider

Throws:

Exception

reset

public void reset()
           throws Exception

Description copied from interface: ResultObjectProvider

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.

Specified by:

reset in interface ResultObjectProvider

Throws:

Exception

close

public void close()
           throws Exception

Description copied from interface: ResultObjectProvider

Free the resources associated with this provider.

Specified by:

close in interface ResultObjectProvider

Specified by:

close in interface Closeable

Throws:

Exception

handleCheckedException

public void handleCheckedException(Exception e)

Description copied from interface: ResultObjectProvider

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

Specified by:

handleCheckedException in interface ResultObjectProvider