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  /*
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
   *
   * Copyright (c) 1997-2010 Oracle and/or its affiliates. All rights reserved.
   *
   * The contents of this file are subject to the terms of either the GNU
   * General Public License Version 2 only ("GPL") or the Common Development
   * and Distribution License("CDDL") (collectively, the "License").  You
   * may not use this file except in compliance with the License.  You can
  * obtain a copy of the License at
  * https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html
  * or packager/legal/LICENSE.txt.  See the License for the specific
  * language governing permissions and limitations under the License.
  *
  * When distributing the software, include this License Header Notice in each
  * file and include the License file at packager/legal/LICENSE.txt.
  *
  * GPL Classpath Exception:
  * Oracle designates this particular file as subject to the "Classpath"
  * exception as provided by Oracle in the GPL Version 2 section of the License
  * file that accompanied this code.
  *
  * Modifications:
  * If applicable, add the following below the License Header, with the fields
  * enclosed by brackets [] replaced by your own identifying information:
  * "Portions Copyright [year] [name of copyright owner]"
  *
  * Contributor(s):
  * If you wish your version of this file to be governed by only the CDDL or
  * only the GPL Version 2, indicate your decision by adding "[Contributor]
  * elects to include this software in this distribution under the [CDDL or GPL
  * Version 2] license."  If you don't indicate a single choice of license, a
  * recipient has the option to distribute your version of this file under
  * either the CDDL, the GPL Version 2 or to extend the choice of license to
  * its licensees as provided above.  However, if you add GPL Version 2 code
  * and therefore, elected the GPL Version 2 license, then the option applies
  * only if the new code is made subject to such option by the copyright
  * holder.
  */
 
 package javax.faces;
 
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
 
  class TypedCollections {

    
Dynamically check that the members of the collection are all instances of the given type (or null).
 
     private static boolean checkCollectionMembers(Collection<?> cClass<?> type) {
         for (Object element : c) {
             if (element != null && !type.isInstance(element)) {
                 return false;
             }
         }
         return true;
     }

    
Dynamically check that the members of the collection are all instances of the given type (or null), and that the collection itself is of the given collection type.

Parameters:
<E> the collection's element type
c the collection to cast
type the class of the collection's element type.
Returns:
the dynamically-type checked collection.
Throws:
java.lang.ClassCastException
 
     @SuppressWarnings("unchecked")
      static <E,TypedC extends Collection<E>> TypedC dynamicallyCastCollection(Collection<?> c,
                                                                                           Class<E> type
                                                                                           Class<TypedC> collectionType) {
         if (c == null)
             return null;
         if (!collectionType.isInstance(c))
             throw new ClassCastException(c.getClass().getName());
         assert checkCollectionMembers(ctype) :
             "The collection contains members with a type other than " + type.getName();
 
         return collectionType.cast(c);
     }

    
Dynamically check that the members of the list are all instances of the given type (or null).

Parameters:
<E> the list's element type
list the list to cast
type the class of the list's element type.
Returns:
the dynamically-type checked list.
Throws:
java.lang.ClassCastException
    @SuppressWarnings("unchecked")
     static <E> List<E> dynamicallyCastList(List<?> listClass<E> type) {
        return dynamicallyCastCollection(listtypeList.class);
    }

    
Dynamically check that the members of the set are all instances of the given type (or null).

Parameters:
<E> the set's element type
set the set to cast
type the class of the set's element type.
Returns:
the dynamically-type checked set.
Throws:
java.lang.ClassCastException
    @SuppressWarnings("unchecked")
     static <E> Set<E> dynamicallyCastSet(Set<?> set
                                                      Class<E> type) {
        return dynamicallyCastCollection(settypeSet.class);
    }

    
Dynamically check that the keys and values in the map are all instances of the correct types (or null).

Parameters:
<K> the map's key type
<V> the map's value type
map the map to cast
keyType the class of the map's key type.
valueType the class of the map's value type.
Returns:
the dynamically-type checked map.
Throws:
java.lang.ClassCastException
    @SuppressWarnings("unchecked")
     static <K, V> Map<K, V> dynamicallyCastMap(Map<?, ?> map,
                                                            Class<K> keyType
                                                            Class<V> valueType) {
        if (map == null) {
            return null;                                                                     
        }
        assert checkCollectionMembers(map.keySet(), keyType) :
            "The map contains keys with a type other than " + keyType.getName();
        assert checkCollectionMembers(map.values(), valueType) :
            "The map contains values with a type other than " + valueType.getName();
        return (Map<K, V>) map;
    }
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