# DefaultValues.java

    /*
     * Copyright (c) 2008, Michael Hunger. All Rights Reserved.
     *
     * Licensed under the Apache License, Version 2.0 (the "License");
     * you may not use this file except in compliance with the License.
     * You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
     * Unless required by applicable law or agreed to in writing, software
     * distributed under the License is distributed on an "AS IS" BASIS,
     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     * See the License for the specific language governing permissions and
     * limitations under the License.
     *
     */

    package org.qi4j.api.property;

    import java.lang.reflect.ParameterizedType;
    import java.lang.reflect.Type;
    import java.util.ArrayList;
    import java.util.Collection;
    import java.util.HashMap;
    import java.util.HashSet;
    import java.util.LinkedHashMap;
    import java.util.Map;
    import java.util.Set;

    /**
     * Default values for various property types
     */
    public final class DefaultValues
    {
        private static final Map<Type, Object> DEFAULT_VALUES = new HashMap<Type, Object>();

        static
        {
            DEFAULT_VALUES.put( Byte.class, 0 );
            DEFAULT_VALUES.put( Short.class, 0 );
            DEFAULT_VALUES.put( Character.class, 0 );
            DEFAULT_VALUES.put( Integer.class, 0 );
            DEFAULT_VALUES.put( Long.class, 0L );
            DEFAULT_VALUES.put( Double.class, 0D );
            DEFAULT_VALUES.put( Float.class, 0F );
            DEFAULT_VALUES.put( Boolean.class, false );
            DEFAULT_VALUES.put( String.class, "" );
        }

        public static Object getDefaultValueOf( Type type )
        {
            Object value = DEFAULT_VALUES.get( type );
            if( value != null )
            {
                return value;
            }
            if( type instanceof ParameterizedType )
            {
                // List<Foo> -> List
                type = ( (ParameterizedType) type ).getRawType();
            }

            if( type instanceof Class )
            {
                Class typeAsClass = (Class) type;
                if( Set.class.isAssignableFrom( typeAsClass ) )
                {
                    return new HashSet();
                }
                else if( Map.class.isAssignableFrom( typeAsClass ) )
                {
                    return new LinkedHashMap();
                }
                else if( Collection.class.isAssignableFrom( typeAsClass ) )
                {
                    return new ArrayList();
                }
                else if( typeAsClass.isEnum() )
                {
                    return ( (Class) type ).getEnumConstants()[ 0 ];
                }
            }
            throw new IllegalArgumentException( "Cannot use @UseDefaults with type " + type.toString() );
        }
    }