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.collections.functors;
18
19 import java.io.Serializable;
20
21 import org.apache.commons.collections.Predicate;
22
23 /**
24 * Predicate implementation that always returns false.
25 *
26 * @since 3.0
27 * @version $Id: FalsePredicate.java 1429905 2013-01-07 17:15:14Z ggregory $
28 */
29 public final class FalsePredicate<T> implements Predicate<T>, Serializable {
30
31 /** Serial version UID */
32 private static final long serialVersionUID = 7533784454832764388L;
33
34 /** Singleton predicate instance */
35 public static final Predicate<Object> INSTANCE = new FalsePredicate<Object>();
36
37 /**
38 * Get a typed instance.
39 *
40 * @param <T> the type that the predicate queries
41 * @return the singleton instance
42 * @since 4.0
43 */
44 @SuppressWarnings("unchecked")
45 public static <T> Predicate<T> falsePredicate() {
46 return (Predicate<T>) INSTANCE;
47 }
48
49 /**
50 * Restricted constructor.
51 */
52 private FalsePredicate() {
53 super();
54 }
55
56 /**
57 * Evaluates the predicate returning false always.
58 *
59 * @param object the input object
60 * @return false always
61 */
62 public boolean evaluate(final T object) {
63 return false;
64 }
65
66 private Object readResolve() {
67 return INSTANCE;
68 }
69
70 }