001/*
002  GRANITE DATA SERVICES
003  Copyright (C) 2011 GRANITE DATA SERVICES S.A.S.
004
005  This file is part of Granite Data Services.
006
007  Granite Data Services is free software; you can redistribute it and/or modify
008  it under the terms of the GNU Library General Public License as published by
009  the Free Software Foundation; either version 2 of the License, or (at your
010  option) any later version.
011
012  Granite Data Services is distributed in the hope that it will be useful, but
013  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
014  FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public License
015  for more details.
016
017  You should have received a copy of the GNU Library General Public License
018  along with this library; if not, see <http://www.gnu.org/licenses/>.
019*/
020
021package org.granite.util;
022
023import java.lang.reflect.ParameterizedType;
024import java.lang.reflect.Type;
025import java.lang.reflect.WildcardType;
026import java.util.HashMap;
027import java.util.Map;
028import java.util.SortedMap;
029import java.util.TreeMap;
030
031/**
032 * @author Franck WOLFF
033 */
034public class MapUtil {
035
036    public static Type[] getComponentTypes(Type mapType) {
037        final Class<?> mapClass = TypeUtil.classOfType(mapType);
038
039        if (!Map.class.isAssignableFrom(mapClass))
040            return null;
041
042        Type[] componentTypes = new Type[] {
043            WildcardType.class,
044            WildcardType.class
045        };
046
047        if (mapType instanceof ParameterizedType) {
048            Type[] argTypes = ((ParameterizedType)mapType).getActualTypeArguments();
049            if (argTypes != null) {
050                if (argTypes.length > 0)
051                    componentTypes[0] = argTypes[0];
052                if (argTypes.length > 1)
053                    componentTypes[1] = argTypes[1];
054            }
055        }
056
057        return componentTypes;
058    }
059
060    @SuppressWarnings("unchecked")
061    public static Map<Object, Object> newMap(Class<?> targetClass, int length)
062        throws InstantiationException, IllegalAccessException  {
063
064        if (targetClass.isInterface()) {
065
066            if (SortedMap.class.isAssignableFrom(targetClass))
067                return new TreeMap<Object, Object>();
068
069            if (targetClass.isAssignableFrom(HashMap.class))
070                return new HashMap<Object, Object>(length);
071
072            throw new IllegalArgumentException("Unsupported collection interface: " + targetClass);
073        }
074
075        return (Map<Object, Object>)targetClass.newInstance();
076    }
077}