01: /*
02: * Licensed to the Apache Software Foundation (ASF) under one or more
03: * contributor license agreements. See the NOTICE file distributed with
04: * this work for additional information regarding copyright ownership.
05: * The ASF licenses this file to You under the Apache License, Version 2.0
06: * (the "License"); you may not use this file except in compliance with
07: * the License. You may obtain a copy of the License at
08: *
09: * 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: }
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