Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.commons.collections4; /** * Defines a functor interface implemented by classes that perform a predicate * test on an object. * <p/> * A <code>Predicate</code> is the object equivalent of an <code>if</code> statement. * It uses the input object to return a true or false value, and is often used in * validation or filtering. * <p/> * Standard implementations of common predicates are provided by * {@link PredicateUtils}. These include true, false, instanceof, equals, and, * or, not, method invokation and null testing. * * @param <T> the type that the predicate queries * @version $Id$ * @since 1.0 */ public interface Predicate<T> { /** * Use the specified parameter to perform a test that returns true or false. * * @param object the object to evaluate, should not be changed * @return true or false * @throws ClassCastException (runtime) if the input is the wrong class * @throws IllegalArgumentException (runtime) if the input is invalid * @throws FunctorException (runtime) if the predicate encounters a problem */ boolean evaluate(T object); }