org.exolab.castor.mapping
Class AbstractFieldHandler

java.lang.Object
  org.exolab.castor.mapping.loader.FieldHandlerFriend
      org.exolab.castor.mapping.ExtendedFieldHandler
          org.exolab.castor.mapping.AbstractFieldHandler

All Implemented Interfaces:

FieldHandler

Direct Known Subclasses:

GeneralizedFieldHandler, XMLFieldHandler

public abstract class AbstractFieldHandler

extends ExtendedFieldHandler

An extended version of the FieldHandler interface which is used for adding additional functionality while preserving backward compatability.

Version:

$Revision: 1.4 $ $Date: 2003/09/23 20:44:50 $

Author:

Keith Visco

See Also:

FieldDescriptor, FieldHandler

Method Summary

abstract java.lang.Object	getValue(java.lang.Object object) Returns the value of the field from the object.
boolean	hasValue(java.lang.Object object) Returns true if the "handled" field has a value within the given object.
abstract java.lang.Object	newInstance(java.lang.Object parent) Creates a new instance of the object described by this field.
abstract java.lang.Object	newInstance(java.lang.Object parent, java.lang.Object[] args) Creates a new instance of the object described by this field.
abstract void	resetValue(java.lang.Object object) Sets the value of the field to a default value.
abstract void	setValue(java.lang.Object object, java.lang.Object value) Sets the value of the field on the object.

Methods inherited from class org.exolab.castor.mapping.ExtendedFieldHandler

checkValidity

Methods inherited from class java.lang.Object

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

Method Detail

hasValue

public boolean hasValue(java.lang.Object object)

Returns true if the "handled" field has a value within the given object.

By default this just checks for null. Normally this method is needed for checking if a value has been set via a call to the setValue method, or if the primitive value has been initialized by the JVM.

This method should be overloaded for improved value checking.

Returns:

true if the given object has a value for the handled field

getValue

public abstract java.lang.Object getValue(java.lang.Object object)
                                   throws java.lang.IllegalStateException

Returns the value of the field from the object.

Specified by:

getValue in interface FieldHandler

Specified by:

getValue in class ExtendedFieldHandler

Parameters:

object - The object

Returns:

The value of the field

Throws:

java.lang.IllegalStateException - The Java object has changed and is no longer supported by this handler, or the handler is not compatiable with the Java object

newInstance

public abstract java.lang.Object newInstance(java.lang.Object parent)
                                      throws java.lang.IllegalStateException

Creates a new instance of the object described by this field.

Specified by:

newInstance in interface FieldHandler

Specified by:

newInstance in class ExtendedFieldHandler

Parameters:

parent - The object for which the field is created

Returns:

A new instance of the field's value

Throws:

java.lang.IllegalStateException - This field is a simple type and cannot be instantiated

newInstance

public abstract java.lang.Object newInstance(java.lang.Object parent,
                                             java.lang.Object[] args)
                                      throws java.lang.IllegalStateException

Creates a new instance of the object described by this field.

Specified by:

newInstance in class ExtendedFieldHandler

Parameters:

parent - The object for which the field is created

args - the set of constructor arguments

Returns:

A new instance of the field's value

Throws:

java.lang.IllegalStateException - This field is a simple type and cannot be instantiated

resetValue

public abstract void resetValue(java.lang.Object object)
                         throws java.lang.IllegalStateException,
                                java.lang.IllegalArgumentException

Sets the value of the field to a default value.

Reference fields are set to null, primitive fields are set to their default value, collection fields are emptied of all elements.

Specified by:

resetValue in interface FieldHandler

Specified by:

resetValue in class ExtendedFieldHandler

Parameters:

object - The object

Throws:

java.lang.IllegalStateException - The Java object has changed and is no longer supported by this handler, or the handler is not compatiable with the Java object

java.lang.IllegalArgumentException

setValue

public abstract void setValue(java.lang.Object object,
                              java.lang.Object value)
                       throws java.lang.IllegalStateException,
                              java.lang.IllegalArgumentException

Sets the value of the field on the object.

Specified by:

setValue in interface FieldHandler

Specified by:

setValue in class ExtendedFieldHandler

Parameters:

object - The object

value - The new value

Throws:

java.lang.IllegalStateException - The Java object has changed and is no longer supported by this handler, or the handler is not compatiable with the Java object

java.lang.IllegalArgumentException