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.collections4;
18
19 /**
20 * Defines a functor interface implemented by classes that perform a predicate
21 * test on an object.
22 * <p>
23 * A {@code Predicate} is the object equivalent of an {@code if} statement.
24 * It uses the input object to return a true or false value, and is often used in
25 * validation or filtering.
26 * </p>
27 * <p>
28 * Standard implementations of common predicates are provided by
29 * {@link PredicateUtils}. These include true, false, instanceof, equals, and,
30 * or, not, method invocation and null testing.
31 * </p>
32 *
33 * @param <T> the type that the predicate queries
34 *
35 * @since 1.0
36 */
37 @FunctionalInterface
38 public interface Predicate<T> {
39
40 /**
41 * Use the specified parameter to perform a test that returns true or false.
42 *
43 * @param object the object to evaluate, should not be changed
44 * @return true or false
45 * @throws ClassCastException (runtime) if the input is the wrong class
46 * @throws IllegalArgumentException (runtime) if the input is invalid
47 * @throws FunctorException (runtime) if the predicate encounters a problem
48 */
49 boolean evaluate(T object);
50
51 }