1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.betwixt.expression;
18
19 import java.util.Collection;
20
21 /**
22 * Updates a Collection by adding the new value to it.
23 * @since 0.8
24 */
25 public class CollectionUpdater implements Updater {
26
27 private static CollectionUpdater INSTANCE;
28
29 /**
30 * Gets singleton instance.
31 * @return <code>CollectionUpdater</code>, not null
32 */
33 public static synchronized CollectionUpdater getInstance() {
34 if (INSTANCE == null) {
35 INSTANCE = new CollectionUpdater();
36 }
37 return INSTANCE;
38 }
39
40 /**
41 * Updates collection contained by the context by adding the new value.
42 * @param context <code>Context</code>, not null
43 * @param newValue value to be added, possibly null
44 */
45 public void update(Context context, Object newValue) {
46 if (newValue != null) {
47 Object subject = context.getBean();
48 if (subject != null && subject instanceof Collection) {
49 Collection collection = (Collection) subject;
50 collection.add(newValue);
51 }
52 }
53 }
54 }