org.apache.commons.beanutils
Class BeanPropertyValueEqualsPredicate

java.lang.Object
  extended byorg.apache.commons.beanutils.BeanPropertyValueEqualsPredicate
All Implemented Interfaces:
org.apache.commons.collections.Predicate

public class BeanPropertyValueEqualsPredicate
extends java.lang.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...

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...

Author:
Norm Deane
See Also:
PropertyUtils, Predicate

Field Summary
private  boolean ignoreNull
          Should null objects in the property path be ignored?
private  org.apache.commons.logging.Log log
          For logging.
private  java.lang.String propertyName
          The name of the property which will be evaluated when this Predicate is executed.
private  java.lang.Object propertyValue
          The value that the property specified by propertyName will be compared to when this Predicate executes.
 
Constructor Summary
BeanPropertyValueEqualsPredicate(java.lang.String propertyName, java.lang.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(java.lang.String propertyName, java.lang.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
 boolean evaluate(java.lang.Object object)
          Evaulates the object provided against the criteria specified when this BeanPropertyValueEqualsPredicate was constructed.
private  boolean evaluateValue(java.lang.Object expected, java.lang.Object actual)
          Utility method which evaluates whether the actual property value equals the expected property value.
 java.lang.String getPropertyName()
          Returns the name of the property which will be evaluated when this Predicate is executed.
 java.lang.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
 

Field Detail

log

private final org.apache.commons.logging.Log log
For logging.


propertyName

private java.lang.String propertyName
The name of the property which will be evaluated when this Predicate is executed.


propertyValue

private java.lang.Object propertyValue
The value that the property specified by propertyName will be compared to when this Predicate executes.


ignoreNull

private boolean ignoreNull

Should null objects in the property path be ignored?

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.

Constructor Detail

BeanPropertyValueEqualsPredicate

public BeanPropertyValueEqualsPredicate(java.lang.String propertyName,
                                        java.lang.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:
java.lang.IllegalArgumentException - If the property name provided is null or empty.

BeanPropertyValueEqualsPredicate

public BeanPropertyValueEqualsPredicate(java.lang.String propertyName,
                                        java.lang.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:
java.lang.IllegalArgumentException - If the property name provided is null or empty.
Method Detail

evaluate

public boolean evaluate(java.lang.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:
java.lang.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

private boolean evaluateValue(java.lang.Object expected,
                              java.lang.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 java.lang.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 java.lang.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.


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