EONullValue

Inherits from:

(com.apple.client.eocontrol) Object
(com.apple.yellow.eocontrol) NSObject

Implements:

(com.apple.client.eocontrol only) NSCoding

(com.apple.client.eocontrol only) EOSortOrdering.Comparison

(com.apple.client.eocontrol only) Cloneable

Package:

com.apple.client.eocontrol

com.apple.yellow.eocontrol

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 static method. 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 (com.apple.client.eocontrol only)

classForCoder

encodeWithCoder

EOSortOrderingComparison

compareAscending

compareCaseInsensitiveAscending

compareCaseInsensitiveDescending

compareDescending

Cloneable (com.apple.client.eocontrol only)

Constructors

EONullValue

public EONullValue()

Static Methods

nullValue

public static EONullValue nullValue()