NullElementPointer (Apache Commons JXPath 1.4-SNAPSHOT API)

java.lang.Object
- org.apache.commons.jxpath.ri.model.NodePointer
- - org.apache.commons.jxpath.ri.model.beans.CollectionPointer
  - - org.apache.commons.jxpath.ri.model.beans.NullElementPointer

All Implemented Interfaces:

Serializable, Cloneable, Comparable, Pointer
```
public class NullElementPointer
extends CollectionPointer
```
Used when there is a need to construct a Pointer for a collection element that does not exist. For example, if the path is "foo[3]", but the collection "foo" only has one element or is empty or is null, the NullElementPointer can be used to capture this situation without putting a regular NodePointer into an invalid state. Just create a NullElementPointer with index 2 (= 3 - 1) and a "foo" pointer as the parent.

Version:

$Revision: 652884 $ $Date: 2008-05-02 22:02:00 +0200 (Fr, 02 Mai 2008) $

Author:

Dmitri Plotnikov

See Also:
Serialized Form

Field Summary
- Fields inherited from class org.apache.commons.jxpath.ri.model.NodePointer
  index, locale, parent, UNKNOWN_NAMESPACE, WHOLE_COLLECTION

Constructor Summary

Constructors
Constructor and Description

NullElementPointer(NodePointer parent, int index)
Create a new NullElementPointer.

Constructors
Constructor and Description
`NullElementPointer(NodePointer parent, int index)` Create a new NullElementPointer.

Method Summary

Methods
Modifier and Type	Method and Description
`String`	`asPath()` Returns an XPath that maps to this Pointer.
`NodePointer`	`createPath(JXPathContext context)` Called by a child pointer when it needs to create a parent object.
`NodePointer`	`createPath(JXPathContext context, Object value)` Called directly by JXPathContext.
`boolean`	`equals(Object object)`
`Object`	`getBaseValue()` Returns the value represented by the pointer before indexing.
`Object`	`getImmediateNode()` Returns the object the pointer points to; does not convert it to a "canonical" type.
`int`	`getLength()` If the pointer represents a collection (or collection element), returns the length of the collection.
`QName`	`getName()` Returns the name of this node.
`PropertyPointer`	`getPropertyPointer()` Get the property pointer for this.
`NodePointer`	`getValuePointer()` If this pointer manages a transparent container, like a variable, this method returns the pointer to the contents.
`int`	`hashCode()`
`boolean`	`isActual()` An actual pointer points to an existing part of an object graph, even if it is null.
`boolean`	`isCollection()` Returns `true` if the value of the pointer is an array or a Collection.
`boolean`	`isContainer()` If true, this node is auxiliary and can only be used as an intermediate in the chain of pointers.
`boolean`	`isLeaf()` If true, this node does not have children
`void`	`setValue(Object value)` Converts the value to the required type and changes the corresponding object to that value.

Methods inherited from class org.apache.commons.jxpath.ri.model.beans.CollectionPointer
attributeIterator, childIterator, compareChildNodePointers, createChild, createChild, namespaceIterator, namespacePointer, setIndex, testNode

Methods inherited from class org.apache.commons.jxpath.ri.model.NodePointer
clone, compareTo, createAttribute, escape, getAbstractFactory, getDefaultNamespaceURI, getImmediateParentPointer, getImmediateValuePointer, getIndex, getLocale, getNamespaceResolver, getNamespaceURI, getNamespaceURI, getNode, getNodeSetByKey, getNodeValue, getParent, getPointerByID, getPointerByKey, getRootNode, getValue, handle, handle, isAttribute, isDefaultNamespace, isLanguage, isNode, isRoot, newChildNodePointer, newNodePointer, printPointerChain, remove, setAttribute, setExceptionHandler, setNamespaceResolver, toString, verify

Methods inherited from class java.lang.Object
finalize, getClass, notify, notifyAll, wait, wait, wait

- Constructor Detail
  - NullElementPointer
```
public NullElementPointer(NodePointer parent,
                  int index)
```
    Create a new NullElementPointer.
    
    Parameters:
    parent - parent pointer
    index - int
- Method Detail
  - getName
```
public QName getName()
```
    Description copied from class: NodePointer
    
    Returns the name of this node. Can be null.
    
    Overrides:
    
    getName in class CollectionPointer
    
    Returns:
    QName
  - getBaseValue
```
public Object getBaseValue()
```
    Description copied from class: NodePointer
    
    Returns the value represented by the pointer before indexing. So, if the node represents an element of a collection, this method returns the collection itself.
    
    Overrides:
    
    getBaseValue in class CollectionPointer
    
    Returns:
    Object value
  - getImmediateNode
```
public Object getImmediateNode()
```
    Description copied from class: NodePointer
    
    Returns the object the pointer points to; does not convert it to a "canonical" type.
    
    Overrides:
    
    getImmediateNode in class CollectionPointer
    
    Returns:
    Object node
  - isLeaf
```
public boolean isLeaf()
```
    Description copied from class: NodePointer
    
    If true, this node does not have children
    
    Overrides:
    
    isLeaf in class CollectionPointer
    
    Returns:
    boolean
  - isCollection
```
public boolean isCollection()
```
    Description copied from class: NodePointer
    
    Returns true if the value of the pointer is an array or a Collection.
    
    Overrides:
    
    isCollection in class CollectionPointer
    
    Returns:
    boolean
  - getPropertyPointer
```
public PropertyPointer getPropertyPointer()
```
    Get the property pointer for this.
    
    Returns:
    PropertyPointer
  - getValuePointer
```
public NodePointer getValuePointer()
```
    Description copied from class: NodePointer
    
    If this pointer manages a transparent container, like a variable, this method returns the pointer to the contents. Only an auxiliary (non-node) pointer can (and should) return a value pointer other than itself. Note that you probably don't want to override getValuePointer() directly. Override the getImmediateValuePointer() method instead. The getValuePointer() method is calls getImmediateValuePointer() and, if the result is not this, invokes getValuePointer() recursively. The idea here is to open all nested containers. Let's say we have a container within a container within a container. The getValuePointer() method should then open all those containers and return the pointer to the ultimate contents. It does so with the above recursion.
    
    Overrides:
    
    getValuePointer in class CollectionPointer
    
    Returns:
    NodePointer
  - setValue
```
public void setValue(Object value)
```
    Description copied from class: NodePointer
    
    Converts the value to the required type and changes the corresponding object to that value.
    
    Specified by:
    
    setValue in interface Pointer
    
    Overrides:
    
    setValue in class CollectionPointer
    
    Parameters:
    value - the value to set
  - isActual
```
public boolean isActual()
```
    Description copied from class: NodePointer
    
    An actual pointer points to an existing part of an object graph, even if it is null. A non-actual pointer represents a part that does not exist at all. For instance consider the pointer "/address/street". If both address and street are not null, the pointer is actual. If address is not null, but street is null, the pointer is still actual. If address is null, the pointer is not actual. (In JavaBeans) if address is not a property of the root bean, a Pointer for this path cannot be obtained at all - actual or otherwise.
    
    Overrides:
    
    isActual in class NodePointer
    
    Returns:
    boolean
  - isContainer
```
public boolean isContainer()
```
    Description copied from class: NodePointer
    
    If true, this node is auxiliary and can only be used as an intermediate in the chain of pointers.
    
    Overrides:
    
    isContainer in class CollectionPointer
    
    Returns:
    boolean
  - createPath
```
public NodePointer createPath(JXPathContext context)
```
    Description copied from class: NodePointer
    
    Called by a child pointer when it needs to create a parent object. Must create an object described by this pointer and return a new pointer that properly describes the new object.
    
    Overrides:
    
    createPath in class CollectionPointer
    
    Parameters:
    context - the owning JXPathContext
    
    Returns:
    created NodePointer
  - createPath
```
public NodePointer createPath(JXPathContext context,
                     Object value)
```
    Description copied from class: NodePointer
    
    Called directly by JXPathContext. Must create path and set value.
    
    Overrides:
    
    createPath in class CollectionPointer
    
    Parameters:
    context - the owning JXPathContext
    value - the new value to set
    
    Returns:
    created NodePointer
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class CollectionPointer
  - equals
```
public boolean equals(Object object)
```
    Overrides:
    
    equals in class CollectionPointer
  - getLength
```
public int getLength()
```
    Description copied from class: NodePointer
    
    If the pointer represents a collection (or collection element), returns the length of the collection. Otherwise returns 1 (even if the value is null).
    
    Overrides:
    
    getLength in class CollectionPointer
    
    Returns:
    int
  - asPath
```
public String asPath()
```
    Description copied from class: NodePointer
    
    Returns an XPath that maps to this Pointer.
    
    Specified by:
    
    asPath in interface Pointer
    
    Overrides:
    
    asPath in class CollectionPointer
    
    Returns:
    String xpath expression

Class NullElementPointer

Field Summary

Fields inherited from class org.apache.commons.jxpath.ri.model.NodePointer

Constructor Summary

Method Summary

Methods inherited from class org.apache.commons.jxpath.ri.model.beans.CollectionPointer

Methods inherited from class org.apache.commons.jxpath.ri.model.NodePointer

Methods inherited from class java.lang.Object

Constructor Detail

NullElementPointer

Method Detail

getName

getBaseValue

getImmediateNode

isLeaf

isCollection

getPropertyPointer

getValuePointer

setValue

isActual

isContainer

createPath

createPath

hashCode

equals

getLength

asPath