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 */
022package org.granite.util;
023
024import java.lang.reflect.ParameterizedType;
025import java.lang.reflect.Type;
026import java.util.ArrayList;
027import java.util.Collection;
028import java.util.HashSet;
029import java.util.Set;
030import java.util.SortedSet;
031import java.util.TreeSet;
032
033/**
034 * @author Franck WOLFF
035 */
036public 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}