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 */ 017 package org.apache.commons.betwixt.expression; 018 019 import java.util.Collection; 020 021 /** 022 * Updates a Collection by adding the new value to it. 023 * @since 0.8 024 */ 025 public class CollectionUpdater implements Updater { 026 027 private static CollectionUpdater INSTANCE; 028 029 /** 030 * Gets singleton instance. 031 * @return <code>CollectionUpdater</code>, not null 032 */ 033 public static synchronized CollectionUpdater getInstance() { 034 if (INSTANCE == null) { 035 INSTANCE = new CollectionUpdater(); 036 } 037 return INSTANCE; 038 } 039 040 /** 041 * Updates collection contained by the context by adding the new value. 042 * @param context <code>Context</code>, not null 043 * @param newValue value to be added, possibly null 044 */ 045 public void update(Context context, Object newValue) { 046 if (newValue != null) { 047 Object subject = context.getBean(); 048 if (subject != null && subject instanceof Collection) { 049 Collection collection = (Collection) subject; 050 collection.add(newValue); 051 } 052 } 053 } 054 }