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EONullValue

Inherits From:
Object (Java Client)
NSObject (Yellow Box)

Implements:
NSCoding (Java Client only)
EOSortOrderingComparison (Java Client only)
java.lang.Cloneable (Java Client only)

Package:
com.apple.client.eocontrol (Java Client)
com.apple.yellow.eocontrol (Yellow Box)

Class Description

The EONullValue class defines a unique object used to represent null values in collection objects (which don't allow null values). For example, NSDictionaries fetched by an EOAdaptorChannel contain an EONullValue instance for such values. EONullValue is automatically translated to null in enterprise objects, however, so most applications should rarely need to account for this class.

EONullValue has exactly one instance, returned by the nullValue class method. t You can safely cache this instance and use the == operator to test for the presence of a null value:

EONullValue myNull = EONullValue.nullValue();
/* ... */
if (value == myNull) {
/* ... */
}

Interfaces Implemented

NSCoding (Java Client only)
- classForCoder
- encodeWithCoder
EOSortOrderingComparison
- compareAscending
- compareCaseInsensitiveAscending
- compareCaseInsensitiveDescending
- compareDescending
java.lang.Cloneable (Java Client only)

Constructors


EONullValue

public EONullValue ()

Returns the unique instance of EONullValue.

Static Methods


nullValue

public static EONullValue nullValue ()

Returns the unique instance of EONullValue.





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