oracle.toplink.essentials.internal.helper.InvalidObject Maven / Gradle / Ivy
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/*
DESCRIPTION
PRIVATE CLASSES
NOTES
MODIFIED (MM/DD/YY)
pkrogh 10/07/05 -
pkrogh 09/29/05 -
gyorke 08/09/05 - gyorke_10-essentials-directory-creation_050808
dmahar 08/04/05 -
pkrogh 08/28/04 - codeformat
smcritch 05/14/04 - smcritch_refactor_session_read031604
smcritch 04/26/04 - Creation
*/
package oracle.toplink.essentials.internal.helper;
/**
* Purpose:Indicates an object that should not be returned from
* query execution.
*
* When conforming if checkEarly return finds a matching object by exact primary
* key, but that object is deleted, want to return null from query execution.
*
* However if null is returned from checkEarly return that will indicate that
* no object was found and to go to the database. Hence returning null is not
* enough, something else needed to be returned, indicating not only that
* checkEarlyReturn had failed but query execution should not proceed.
*
* Can be used in other instances where returning null is ambiguous.
*
* Implements singleton pattern
* @author Stephen McRitchie
* @since release specific (what release of product did this appear in)
*/
public class InvalidObject {
public static final InvalidObject instance = new InvalidObject();
private InvalidObject() {
}
/**
* @return singleton invalid object.
*/
public static InvalidObject instance() {
return instance;
}
}