diff options
Diffstat (limited to 'projects/net.wotonomy.persistence/src/main/java/net/wotonomy/control/EONullValue.java')
| -rw-r--r-- | projects/net.wotonomy.persistence/src/main/java/net/wotonomy/control/EONullValue.java | 143 |
1 files changed, 68 insertions, 75 deletions
diff --git a/projects/net.wotonomy.persistence/src/main/java/net/wotonomy/control/EONullValue.java b/projects/net.wotonomy.persistence/src/main/java/net/wotonomy/control/EONullValue.java index 3b4544e..1ecce4d 100644 --- a/projects/net.wotonomy.persistence/src/main/java/net/wotonomy/control/EONullValue.java +++ b/projects/net.wotonomy.persistence/src/main/java/net/wotonomy/control/EONullValue.java @@ -23,91 +23,84 @@ import java.io.Serializable; import net.wotonomy.foundation.NSNull; /** -* EONullValue is used to represent null in Collections classes -* because List and Map do not specify whether null values -* are allowed and because NSArray and NSDictionary explicitly -* do not allow null values. <br><br> -* -* Use of the static singleton method nullValue() is required -* by this implementation because Java cannot return a singleton -* instance from a constructor. <br><br> -* -* This implementation duplicates NSNull, but the singleton instances -* are of course different. Be careful. I have no idea why this -* class was even created, given that NSNull exists. -* -* @author michael@mpowers.net -* @author $Author: cgruber $ -* @version $Revision: 894 $ -*/ -public class EONullValue implements Serializable -{ - private static final EONullValue instance = new EONullValue(); - - /** - * Create a new instance of EONullValue. - */ - private EONullValue () - { - } + * EONullValue is used to represent null in Collections classes because List and + * Map do not specify whether null values are allowed and because NSArray and + * NSDictionary explicitly do not allow null values. <br> + * <br> + * + * Use of the static singleton method nullValue() is required by this + * implementation because Java cannot return a singleton instance from a + * constructor. <br> + * <br> + * + * This implementation duplicates NSNull, but the singleton instances are of + * course different. Be careful. I have no idea why this class was even created, + * given that NSNull exists. + * + * @author michael@mpowers.net + * @author $Author: cgruber $ + * @version $Revision: 894 $ + */ +public class EONullValue implements Serializable { + private static final EONullValue instance = new EONullValue(); - /** - * Constructor specifying name and object. - */ - public static EONullValue nullValue () - { - return instance; - } + /** + * Create a new instance of EONullValue. + */ + private EONullValue() { + } - /** - * Returns a human-readable string representation. - */ - public String toString() - { - return "[null]"; - } - - /** - * Hashcode of all instances is zero. - */ - public int hashCode() - { - return 0; - } - - /** - * Implemented to return true for any instance of EONullValue - * and for any instance of NSNull. - */ - public boolean equals( Object anObject ) - { - if ( anObject instanceof EONullValue ) return true; - if ( anObject instanceof NSNull ) return true; - return false; - } + /** + * Constructor specifying name and object. + */ + public static EONullValue nullValue() { + return instance; + } + + /** + * Returns a human-readable string representation. + */ + public String toString() { + return "[null]"; + } + + /** + * Hashcode of all instances is zero. + */ + public int hashCode() { + return 0; + } + + /** + * Implemented to return true for any instance of EONullValue and for any + * instance of NSNull. + */ + public boolean equals(Object anObject) { + if (anObject instanceof EONullValue) + return true; + if (anObject instanceof NSNull) + return true; + return false; + } } /* - * $Log$ - * Revision 1.2 2006/02/16 16:47:14 cgruber - * Move some classes in to "internal" packages and re-work imports, etc. + * $Log$ Revision 1.2 2006/02/16 16:47:14 cgruber Move some classes in to + * "internal" packages and re-work imports, etc. * - * Also use UnsupportedOperationExceptions where appropriate, instead of WotonomyExceptions. + * Also use UnsupportedOperationExceptions where appropriate, instead of + * WotonomyExceptions. * - * Revision 1.1 2006/02/16 13:19:57 cgruber - * Check in all sources in eclipse-friendly maven-enabled packages. + * Revision 1.1 2006/02/16 13:19:57 cgruber Check in all sources in + * eclipse-friendly maven-enabled packages. * - * Revision 1.3 2003/08/06 23:07:52 chochos - * general code cleanup (mostly, removing unused imports) + * Revision 1.3 2003/08/06 23:07:52 chochos general code cleanup (mostly, + * removing unused imports) * - * Revision 1.2 2001/03/01 20:35:38 mpowers - * Implemented equals and hashCode. + * Revision 1.2 2001/03/01 20:35:38 mpowers Implemented equals and hashCode. * - * Revision 1.1 2001/02/26 22:41:51 mpowers - * Implemented null placeholder classes. - * Duplicator now uses NSNull. - * No longer catching base exception class. + * Revision 1.1 2001/02/26 22:41:51 mpowers Implemented null placeholder + * classes. Duplicator now uses NSNull. No longer catching base exception class. * * */ - |