    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.collections4;
    018
    019/**
    020 * Defines a functor interface implemented by classes that perform a predicate
    021 * test on an object.
    022 * <p>
    023 * A <code>Predicate</code> is the object equivalent of an <code>if</code> statement.
    024 * It uses the input object to return a true or false value, and is often used in
    025 * validation or filtering.
    026 * <p>
    027 * Standard implementations of common predicates are provided by
    028 * {@link PredicateUtils}. These include true, false, instanceof, equals, and,
    029 * or, not, method invokation and null testing.
    030 *
    031 * @param <T> the type that the predicate queries
    032 *
    033 * @since 1.0
    034 */
    035public interface Predicate<T> {
    036
    037    /**
    038     * Use the specified parameter to perform a test that returns true or false.
    039     *
    040     * @param object  the object to evaluate, should not be changed
    041     * @return true or false
    042     * @throws ClassCastException (runtime) if the input is the wrong class
    043     * @throws IllegalArgumentException (runtime) if the input is invalid
    044     * @throws FunctorException (runtime) if the predicate encounters a problem
    045     */
    046    boolean evaluate(T object);
    047
    048}