Package org.apache.commons.collections.collection

Class PredicatedCollection

java.lang.Object
org.apache.commons.collections.collection.AbstractCollectionDecorator
org.apache.commons.collections.collection.AbstractSerializableCollectionDecorator
org.apache.commons.collections.collection.PredicatedCollection
All Implemented Interfaces:
Serializable, Iterable, Collection
Direct Known Subclasses:
PredicatedBag, PredicatedBuffer, PredicatedList, PredicatedSet
public class PredicatedCollection extends AbstractSerializableCollectionDecorator
Decorates another Collection to validate that additions match a specified predicate.

This collection exists to provide validation for the decorated collection. It is normally created to decorate an empty collection. If an object cannot be added to the collection, an IllegalArgumentException is thrown.

One usage would be to ensure that no null entries are added to the collection. 

Collection coll = PredicatedCollection.decorate(new ArrayList(), NotNullPredicate.INSTANCE);

This class is Serializable from Commons Collections 3.1.

Since:
Commons Collections 3.0
Version:
$Revision: 646777 $ $Date: 2008-04-10 14:33:15 +0200 (Thu, 10 Apr 2008) $
Author:
Stephen Colebourne, Paul Jack
See Also:

  • Field Details

    • predicate

      protected final Predicate predicate
      The predicate to use

  • Constructor Details

    • PredicatedCollection

      protected PredicatedCollection(Collection coll, Predicate predicate)
      Constructor that wraps (not copies).

      If there are any elements already in the collection being decorated, they are validated.

      Parameters:
      coll - the collection to decorate, must not be null
      predicate - the predicate to use for validation, must not be null
      Throws:
      IllegalArgumentException - if collection or predicate is null
      IllegalArgumentException - if the collection contains invalid elements

  • Method Details

    • decorate

      public static Collection decorate(Collection coll, Predicate predicate)
      Factory method to create a predicated (validating) collection.

      If there are any elements already in the collection being decorated, they are validated.

      Parameters:
      coll - the collection to decorate, must not be null
      predicate - the predicate to use for validation, must not be null
      Returns:
      a new predicated collection
      Throws:
      IllegalArgumentException - if collection or predicate is null
      IllegalArgumentException - if the collection contains invalid elements

    • validate

      protected void validate(Object object)
      Validates the object being added to ensure it matches the predicate.

      The predicate itself should not throw an exception, but return false to indicate that the object cannot be added.

      Parameters:
      object - the object being added
      Throws:
      IllegalArgumentException - if the add is invalid

    • add

      public boolean add(Object object)
      Override to validate the object being added to ensure it matches the predicate.
      Specified by:
      add in interface Collection
      Overrides:
      add in class AbstractCollectionDecorator
      Parameters:
      object - the object being added
      Returns:
      the result of adding to the underlying collection
      Throws:
      IllegalArgumentException - if the add is invalid

    • addAll

      public boolean addAll(Collection coll)
      Override to validate the objects being added to ensure they match the predicate. If any one fails, no update is made to the underlying collection.
      Specified by:
      addAll in interface Collection
      Overrides:
      addAll in class AbstractCollectionDecorator
      Parameters:
      coll - the collection being added
      Returns:
      the result of adding to the underlying collection
      Throws:
      IllegalArgumentException - if the add is invalid