org.apache.xpath.objects
Class XNull

java.lang.Object
  |
  +--org.apache.xpath.Expression
        |
        +--org.apache.xpath.objects.XObject
              |
              +--org.apache.xpath.objects.XNull

public class XNull

extends XObject

This class represents an XPath null object, and is capable of converting the null to other types, such as a string.

See Also:

Serialized Form

Fields inherited from class org.apache.xpath.objects.XObject

CLASS_BOOLEAN, CLASS_NODESET, CLASS_NULL, CLASS_NUMBER, CLASS_RTREEFRAG, CLASS_STRING, CLASS_UNKNOWN, CLASS_UNRESOLVEDVARIABLE

Constructor Summary

XNull()
Create an XObject.

Method Summary

boolean	bool() Cast result object to a boolean.
boolean	equals(XObject obj2) Tell if two objects are functionally equal.
int	getType() Tell what kind of class this is.
java.lang.String	getTypeString() Given a request type, return the equivalent string.
NodeIterator	nodeset() Cast result object to a nodelist.
double	num() Cast result object to a number.
DocumentFragment	rtree(XPathContext support) Cast result object to a result tree fragment.
java.lang.String	str() Cast result object to a string.

Methods inherited from class org.apache.xpath.objects.XObject

castToType, create, execute, greaterThan, greaterThanOrEqual, lessThan, lessThanOrEqual, mutableNodeset, notEquals, object, rtree, toString

Methods inherited from class org.apache.xpath.Expression

assert, canTraverseOutsideSubtree, error, setSourceLocator, warn

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

XNull

public XNull()

Create an XObject.

Method Detail

getType

public int getType()

Tell what kind of class this is.

Returns:

type CLASS_NULL

Overrides:

getType in class XObject

getTypeString

public java.lang.String getTypeString()

Given a request type, return the equivalent string. For diagnostic purposes.

Returns:

type string "#CLASS_NULL"

Overrides:

getTypeString in class XObject

num

public double num()

Cast result object to a number.

Returns:

0.0

Overrides:

num in class XObject

bool

public boolean bool()

Cast result object to a boolean.

Returns:

false

Overrides:

bool in class XObject

str

public java.lang.String str()

Cast result object to a string.

Returns:

empty string ""

Overrides:

str in class XObject

rtree

public DocumentFragment rtree(XPathContext support)

Cast result object to a result tree fragment.

Parameters:

support - XPath context to use for the conversion

Returns:

The object as a result tree fragment.

Overrides:

rtree in class XObject

nodeset

public NodeIterator nodeset()

Cast result object to a nodelist.

Returns:

null

Overrides:

nodeset in class XObject

equals

public boolean equals(XObject obj2)

Tell if two objects are functionally equal.

Parameters:

obj2 - Object to compare this to

Returns:

True if the given object is of type CLASS_NULL

Overrides:

equals in class XObject