001    /**
002     *   GRANITE DATA SERVICES
003     *   Copyright (C) 2006-2013 GRANITE DATA SERVICES S.A.S.
004     *
005     *   This file is part of the Granite Data Services Platform.
006     *
007     *   Granite Data Services is free software; you can redistribute it and/or
008     *   modify it under the terms of the GNU Lesser General Public
009     *   License as published by the Free Software Foundation; either
010     *   version 2.1 of the License, or (at your option) any later version.
011     *
012     *   Granite Data Services is distributed in the hope that it will be useful,
013     *   but WITHOUT ANY WARRANTY; without even the implied warranty of
014     *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
015     *   General Public License for more details.
016     *
017     *   You should have received a copy of the GNU Lesser General Public
018     *   License along with this library; if not, write to the Free Software
019     *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
020     *   USA, or see <http://www.gnu.org/licenses/>.
021     */
022    package org.granite.util;
023    
024    import java.lang.reflect.ParameterizedType;
025    import java.lang.reflect.Type;
026    import java.util.ArrayList;
027    import java.util.Collection;
028    import java.util.HashSet;
029    import java.util.Set;
030    import java.util.SortedSet;
031    import java.util.TreeSet;
032    
033    /**
034     * @author Franck WOLFF
035     */
036    public class CollectionUtil {
037    
038        public static Type getComponentType(Type collectionType) {
039    
040            Class<?> collectionClass = TypeUtil.classOfType(collectionType);
041            if (collectionClass == null || !Collection.class.isAssignableFrom(collectionClass))
042                return null;
043    
044            if (collectionType instanceof ParameterizedType) {
045                Type[] componentTypes = ((ParameterizedType)collectionType).getActualTypeArguments();
046                if (componentTypes != null && componentTypes.length == 1)
047                    return componentTypes[0];
048            }
049    
050            return Object.class;
051        }
052    
053        @SuppressWarnings("unchecked")
054        public static Collection<Object> newCollection(Class<?> targetClass, int length)
055            throws InstantiationException, IllegalAccessException  {
056    
057            if (targetClass.isInterface()) {
058    
059                if (Set.class.isAssignableFrom(targetClass)) {
060                    if (SortedSet.class.isAssignableFrom(targetClass))
061                        return new TreeSet<Object>();
062                    return new HashSet<Object>(length);
063                }
064    
065                if (targetClass.isAssignableFrom(ArrayList.class))
066                    return new ArrayList<Object>(length);
067    
068                throw new IllegalArgumentException("Unsupported collection interface: " + targetClass);
069            }
070    
071            return (Collection<Object>)targetClass.newInstance();
072        }
073    }