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Java > Open Source Codes > org > apache > commons > collections > Predicate


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 org.apache.commons.collections;
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> statement.
23  * It uses the input object to return a true or false value, and is often used in
24  * validation or filtering.
25  * <p>
26  * Standard implementations of common predicates are provided by
27  * {@link PredicateUtils}. These include true, false, instanceof, equals, and,
28  * or, not, method invokation and null testing.
29  *
30  * @since Commons Collections 1.0
31  * @version $Revision: 1.11 $ $Date: 2004/04/14 20:08:57 $
32  *
33  * @author James Strachan
34  * @author Stephen Colebourne
35  */
36 public interface Predicate {
37
38     /**
39      * Use the specified parameter to perform a test that returns true or false.
40      *
41      * @param object the object to evaluate, should not be changed
42      * @return true or false
43      * @throws ClassCastException (runtime) if the input is the wrong class
44      * @throws IllegalArgumentException (runtime) if the input is invalid
45      * @throws FunctorException (runtime) if the predicate encounters a problem
46      */
47     public boolean evaluate(Object JavaDoc object);
48
49 }
50
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