public class

BeanToPropertyValueTransformer

extends Object
implements Transformer
java.lang.Object
   ↳ org.apache.commons.beanutils.BeanToPropertyValueTransformer

Class Overview

Transformer that outputs a property value.

An implementation of org.apache.commons.collections.Transformer that transforms the object provided by returning the value of a specified property of the object. The constructor for BeanToPropertyValueTransformer requires the name of the property that will be used in the transformation. The property can be a simple, nested, indexed, or mapped property as defined by org.apache.commons.beanutils.PropertyUtils. If any object in the property path specified by propertyName is null then the outcome is based on the value of the ignoreNull attribute.

A typical usage might look like: 

 // create the transformer
 BeanToPropertyValueTransformer transformer = new BeanToPropertyValueTransformer( "person.address.city" );

 // transform the Collection
 Collection peoplesCities = CollectionUtils.collect( peopleCollection, transformer );

This would take a Collection of person objects and return a Collection of objects which represents the cities in which each person lived. Assuming...

  • The top level object in the peeopleCollection is an object which represents a person.
  • The person object has a getAddress() method which returns an object which represents a person's address.
  • The address object has a getCity() method which returns an object which represents the city in which a person lives.

See Also

Summary

Public Constructors
BeanToPropertyValueTransformer(String propertyName)
Constructs a Transformer which does not ignore nulls.
BeanToPropertyValueTransformer(String propertyName, boolean ignoreNull)
Constructs a Transformer and sets ignoreNull.
Public Methods
String getPropertyName()
Returns the name of the property that will be used in the transformation of the bean.
boolean isIgnoreNull()
Returns the flag which determines whether null objects in the property path will genenerate an IllegalArgumentException or not.
Object transform(Object object)
Returns the value of the property named in the transformer's constructor for the object provided.
[Expand]
Inherited Methods
From class java.lang.Object
From interface org.apache.commons.collections.Transformer

Public Constructors

public BeanToPropertyValueTransformer (String propertyName)

Constructs a Transformer which does not ignore nulls. Constructor which takes the name of the property that will be used in the transformation and assumes ignoreNull to be false.

Parameters
propertyName The name of the property that will be used in the transformation.
Throws
IllegalArgumentException If the propertyName is null or empty.

public BeanToPropertyValueTransformer (String propertyName, boolean ignoreNull)

Constructs a Transformer and sets ignoreNull. Constructor which takes the name of the property that will be used in the transformation and a boolean which determines whether null objects in the property path will genenerate an IllegalArgumentException or not.

Parameters
propertyName The name of the property that will be used in the transformation.
ignoreNull Determines whether null objects in the property path will genenerate an IllegalArgumentException or not.
Throws
IllegalArgumentException If the propertyName is null or empty.

Public Methods

public String getPropertyName ()

Returns the name of the property that will be used in the transformation of the bean.

Returns
  • The name of the property that will be used in the transformation of the bean.

public boolean isIgnoreNull ()

Returns the flag which determines whether null objects in the property path will genenerate an IllegalArgumentException or not. If set to true then if any objects in the property path evaluate to null then the IllegalArgumentException throw by PropertyUtils will be logged but not rethrown and null will be returned. If set to false then if any objects in the property path evaluate to null then the IllegalArgumentException throw by PropertyUtils will be logged and rethrown.

Returns
  • The flag which determines whether null objects in the property path will genenerate an IllegalArgumentException or not.

public Object transform (Object object)

Returns the value of the property named in the transformer's constructor for the object provided. If any object in the property path leading up to the target property is null then the outcome will be based on the value of the ignoreNull attribute. By default, ignoreNull is false and would result in an IllegalArgumentException if an object in the property path leading up to the target property is null.

Parameters
object The object to be transformed.
Returns
  • The value of the property named in the transformer's constructor for the object provided.
Throws
IllegalArgumentException If an IllegalAccessException, InvocationTargetException, or NoSuchMethodException is thrown when trying to access the property specified on the object provided. Or if an object in the property path provided is null and ignoreNull is set to false.