org.apache.commons.beanutils

Class BeanPropertyValueEqualsPredicate

java.lang.Object

org.apache.commons.beanutils.BeanPropertyValueEqualsPredicate

All Implemented Interfaces:

org.apache.commons.collections.Predicate

public class BeanPropertyValueEqualsPredicate
extends Object
implements org.apache.commons.collections.Predicate

Predicate that evaluates a property value against a specified value.

An implementation of org.apache.commons.collections.Predicate that evaluates a property value on the object provided against a specified value and returns true if equal; false otherwise. The BeanPropertyValueEqualsPredicate constructor takes two parameters which determine what property will be evaluated on the target object and what its expected value should be.

public BeanPropertyValueEqualsPredicate( String propertyName, Object propertyValue )

Will create a Predicate that will evaluate the target object and return true if the property specified by propertyName has a value which is equal to the the value specified by propertyValue. Or return false otherwise.

Note: Property names 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 closure
 BeanPropertyValueEqualsPredicate predicate =
    new BeanPropertyValueEqualsPredicate( "activeEmployee", Boolean.FALSE );

 // filter the Collection
 CollectionUtils.filter( peopleCollection, predicate );
 

This would take a Collection of person objects and filter out any people whose activeEmployee property is false. Assuming...

• The top level object in the peeopleCollection is an object which represents a person.
• The person object has a getActiveEmployee() method which returns the boolean value for the object's activeEmployee property.

Another typical usage might look like:

 // create the closure
 BeanPropertyValueEqualsPredicate predicate =
    new BeanPropertyValueEqualsPredicate( "personId", "456-12-1234" );

 // search the Collection
 CollectionUtils.find( peopleCollection, predicate );
 

This would search a Collection of person objects and return the first object whose personId property value equals 456-12-1234. Assuming...

• The top level object in the peeopleCollection is an object which represents a person.
• The person object has a getPersonId() method which returns the value for the object's personId property.

Version:

$Id$

See Also:

PropertyUtils, Predicate

Constructor Summary

Constructors

Constructor and Description
BeanPropertyValueEqualsPredicate(String propertyName, Object propertyValue) Constructor which takes the name of the property, its expected value to be used in evaluation, and assumes ignoreNull to be false.
BeanPropertyValueEqualsPredicate(String propertyName, Object propertyValue, boolean ignoreNull) Constructor which takes the name of the property, its expected value to be used in evaluation, and a boolean which determines whether null objects in the property path will genenerate an IllegalArgumentException or not.

Method Summary

Modifier and Type	Method and Description
boolean	evaluate(Object object) Evaulates the object provided against the criteria specified when this BeanPropertyValueEqualsPredicate was constructed.
protected boolean	evaluateValue(Object expected, Object actual) Utility method which evaluates whether the actual property value equals the expected property value.
String	getPropertyName() Returns the name of the property which will be evaluated when this Predicate is executed.
Object	getPropertyValue() Returns the value that the property specified by propertyName will be compared to when this Predicate executes.
boolean	isIgnoreNull() Returns the flag which determines whether null objects in the property path will genenerate an IllegalArgumentException or not.

Methods inherited from class java.lang.Object

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

Constructor Detail

BeanPropertyValueEqualsPredicate

public BeanPropertyValueEqualsPredicate(String propertyName,
                                        Object propertyValue)

Constructor which takes the name of the property, its expected value to be used in evaluation, and assumes ignoreNull to be false.

Parameters:

propertyName - The name of the property that will be evaluated against the expected value.

propertyValue - The value to use in object evaluation.

Throws:

IllegalArgumentException - If the property name provided is null or empty.

BeanPropertyValueEqualsPredicate

public BeanPropertyValueEqualsPredicate(String propertyName,
                                        Object propertyValue,
                                        boolean ignoreNull)

Constructor which takes the name of the property, its expected value to be used in evaluation, 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 evaluated against the expected value.

propertyValue - The value to use in object evaluation.

ignoreNull - Determines whether null objects in the property path will genenerate an IllegalArgumentException or not.

Throws:

IllegalArgumentException - If the property name provided is null or empty.

Method Detail

evaluate

public boolean evaluate(Object object)

Evaulates the object provided against the criteria specified when this BeanPropertyValueEqualsPredicate was constructed. Equality is based on either reference or logical equality as defined by the property object's equals method. 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.

Specified by:

evaluate in interface org.apache.commons.collections.Predicate

Parameters:

object - The object to be evaluated.

Returns:

True if the object provided meets all the criteria for this Predicate; false otherwise.

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.

evaluateValue

protected boolean evaluateValue(Object expected,
                                Object actual)

Utility method which evaluates whether the actual property value equals the expected property value.

Parameters:

expected - The expected value.

actual - The actual value.

Returns:

True if they are equal; false otherwise.

getPropertyName

public String getPropertyName()

Returns the name of the property which will be evaluated when this Predicate is executed.

Returns:

The name of the property which will be evaluated when this Predicate is executed.

getPropertyValue

public Object getPropertyValue()

Returns the value that the property specified by propertyName will be compared to when this Predicate executes.

Returns:

The value that the property specified by propertyName will be compared to when this Predicate executes.

isIgnoreNull

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 false 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.