org.apache.xpath.objects
Class XNull

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

public class XNull

extends XNodeSet

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

Usage:

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.
double	num() Cast result object to a number.
int	rtf(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.XNodeSet

appendToFsb, boolWithSideEffects, compare, dispatchCharactersEvents, getFresh, getNumberFromNode, getStringFromNode, greaterThan, greaterThanOrEqual, iter, iterRaw, lessThan, lessThanOrEqual, mutableNodeset, nodelist, nodeset, notEquals, numWithSideEffects, object, release, xstr

Methods inherited from class org.apache.xpath.axes.NodeSequence

allowDetachToRelease, clone, cloneWithReset, detach, fixupVariables, getAnalysisBits, getAxis, getContainedIter, getCurrentNode, getCurrentPos, getDTM, getDTMManager, getExpandEntityReferences, getLength, getRoot, getWhatToShow, hasCache, isDocOrdered, isFresh, isMutable, item, nextNode, previousNode, reset, runTo, setCurrentPos, setItem, setIter, setRoot, setShouldCacheNodes

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

callVisitors, castToType, create, create, deepEquals, destruct, execute, rtf, rtree, rtree, toString

Methods inherited from class org.apache.xpath.Expression

asIterator, asIteratorRaw, asNode, assertion, bool, canTraverseOutsideSubtree, error, execute, execute, execute, executeCharsToContentHandler, exprAddChild, exprGetChild, exprGetNumChildren, exprGetParent, exprSetParent, getColumnNumber, getExpressionOwner, getLineNumber, getPublicId, getSystemId, isNodesetExpr, isStableNumber, num, warn, xstr

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 XNodeSet

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 XNodeSet

num

public double num()

Cast result object to a number.

Returns:

0.0

Overrides:

num in class XNodeSet

bool

public boolean bool()

Cast result object to a boolean.

Returns:

false

Overrides:

bool in class XNodeSet

str

public java.lang.String str()

Cast result object to a string.

Returns:

empty string ""

Overrides:

str in class XNodeSet

rtf

public int rtf(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:

rtf 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 XNodeSet