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1   /*
2    *  Copyright 2001-2004 The Apache Software Foundation
3    *
4    *  Licensed under the Apache License, Version 2.0 (the "License");
5    *  you may not use this file except in compliance with the License.
6    *  You may obtain a copy of the License at
7    *
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    *
10   *  Unless required by applicable law or agreed to in writing, software
11   *  distributed under the License is distributed on an "AS IS" BASIS,
12   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   *  See the License for the specific language governing permissions and
14   *  limitations under the License.
15   */
16  package net.sf.collections15;
17  
18  /***
19   * Defines a functor interface implemented by classes that perform a predicate
20   * test on an object.
21   * <p/>
22   * A <code>Predicate</code> is the object equivalent of an <code>if</code>
23   * statement. It uses the input object to return a true or false value, and is
24   * often used in validation or filtering.
25   * <p/>
26   * Standard implementations of common predicates are provided by {@link
27   * net.sf.collections15.functors.predicate.PredicateUtils}. These include true,
28   * false, instanceof, equals, and, or, not, method invokation and null testing.
29   *
30   * @author James Strachan
31   * @author Stephen Colebourne
32   * @version $Revision: 1.2 $ $Date: 2004/10/17 01:02:42 $
33   * @since Commons Collections15 1.0
34   */
35  public interface Predicate <E>
36  {
37  
38      /***
39       * Use the specified parameter to perform a test that returns true or
40       * false.
41       *
42       * @param object the object to evaluate, should not be changed
43       *
44       * @return true or false
45       *
46       * @throws ClassCastException       (runtime) if the input is the wrong
47       *                                  class
48       * @throws IllegalArgumentException (runtime) if the input is invalid
49       * @throws net.sf.collections15.functors.FunctorException
50       *                                  (runtime) if the predicate encounters a
51       *                                  problem
52       */
53      public boolean evaluate(E object);
54  
55  }