001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.wicket.markup.repeater.data;
018
019import java.io.Serializable;
020import java.util.Collections;
021import java.util.Iterator;
022import java.util.List;
023
024import org.apache.wicket.model.IModel;
025import org.apache.wicket.model.Model;
026
027
028/**
029 * Allows the use of lists with {@link DataView}. The only requirement is that either list items
030 * must be serializable or model(Object) needs to be overridden to provide the proper model
031 * implementation.
032 * 
033 * @author Igor Vaynberg ( ivaynberg )
034 * @param <T>
035 * 
036 */
037public class ListDataProvider<T extends Serializable> implements IDataProvider<T>
038{
039        private static final long serialVersionUID = 1L;
040
041        /** reference to the list used as dataprovider for the dataview */
042        private final List<T> list;
043
044        /**
045         * Constructs an empty provider. Useful for lazy loading together with {@linkplain #getData()}
046         */
047        public ListDataProvider()
048        {
049                this(Collections.<T> emptyList());
050        }
051
052        /**
053         * 
054         * @param list
055         *            the list used as dataprovider for the dataview
056         */
057        public ListDataProvider(List<T> list)
058        {
059                if (list == null)
060                {
061                        throw new IllegalArgumentException("argument [list] cannot be null");
062                }
063
064                this.list = list;
065        }
066
067        /**
068         * Subclass to lazy load the list
069         * 
070         * @return The list
071         */
072        protected List<T> getData()
073        {
074                return list;
075        }
076
077        @Override
078        public Iterator<T> iterator(final long first, final long count)
079        {
080                List<T> list = getData();
081
082                long toIndex = first + count;
083                if (toIndex > list.size())
084                {
085                        toIndex = list.size();
086                }
087                return list.subList((int)first, (int)toIndex).listIterator();
088        }
089
090        @Override
091        public long size()
092        {
093                return getData().size();
094        }
095
096        @Override
097        public IModel<T> model(T object)
098        {
099                return new Model<>(object);
100        }
101}