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:
    Serialized Form

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `protected Predicate` | `predicate` The predicate to use

    - ### Fields inherited from class org.apache.commons.collections.collection.AbstractCollectionDecorator

      `collection`

  - ### Constructor Summary

    Constructors
    Modifier | Constructor and Description
    --- | ---
    `protected` | `PredicatedCollection(Collection coll, Predicate predicate)` Constructor that wraps (not copies).

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `boolean` | `add(Object object)` Override to validate the object being added to ensure it matches the predicate.
    `boolean` | `addAll(Collection coll)` Override to validate the objects being added to ensure they match the predicate.
    `static Collection` | `decorate(Collection coll, Predicate predicate)` Factory method to create a predicated (validating) collection.
    `protected void` | `validate(Object object)` Validates the object being added to ensure it matches the predicate.

    - ### Methods inherited from class org.apache.commons.collections.collection.AbstractCollectionDecorator

      `clear, contains, containsAll, equals, getCollection, hashCode, isEmpty, iterator, remove, removeAll, retainAll, size, toArray, toArray, toString`

    - ### Methods inherited from class java.lang.Object

      `clone, finalize, getClass, notify, notifyAll, wait, wait, wait`

- - ### Field Detail

    - #### predicate

          protected final Predicate predicate

      The predicate to use

  - ### Constructor Detail

    - #### 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 Detail

    - #### 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

Copyright © 2001–2015 The Apache Software Foundation. All rights reserved.