NSKeyValueCoding.Null

Inherits from:

Object

Implements:

Serializable

Cloneable

NSCoding

Package:

com.webobjects.foundation

Class Description

NSKeyValueCoding.Null is a final class that defines a unique object used to represent null values in collection objects, such as NSArrays, which don't allow null values.

For instance, Enterprise Objects Framework uses NSKeyValueCoding.Null to represent null values from database rows in its database level snapshots (NSDictionary objects). However, Enterprise Objects Framework automatically translates NSKeyValueCoding.Null to null in enterprise objects, so you should rarely need to write code that accounts for this class.

Whenever null is represented by NSKeyValueCoding.Null, it should be represented with the instance stored in the NSKeyValueCoding constant, NullValue. You can safely use this instance with the == operator to test for the presence of a null value:

if (value == NSKeyValueCoding.NullValue) {
    /* ... */
}

Interfaces Implemented

NSCoding

classForCoder

encodeWithCoder

Cloneable

clone

Static Methods

decodeObject

public static Object decodeObject(NSCoder aNSCoder)

See Also: NSCoding Interface Description

Instance Methods

classForCoder

public Class classForCoder()

clone

public Object clone()

encodeWithCoder

public void encodeWithCoder(NSCoder aNSCoder)

toString

public String toString()

© 2001 Apple Computer, Inc. (Last Published April 17, 2001)