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.functors; 018 019import java.io.Serializable; 020import java.util.Objects; 021 022import org.apache.commons.collections4.Factory; 023import org.apache.commons.collections4.Transformer; 024 025/** 026 * Transformer implementation that calls a Factory and returns the result. 027 * 028 * @param <T> the type of the input to the function. 029 * @param <R> the type of the result of the function. 030 * @since 3.0 031 */ 032public class FactoryTransformer<T, R> implements Transformer<T, R>, Serializable { 033 034 /** Serial version UID */ 035 private static final long serialVersionUID = -6817674502475353160L; 036 037 /** 038 * Factory method that performs validation. 039 * 040 * @param <I> the input type 041 * @param <O> the output type 042 * @param factory the factory to call, not null 043 * @return the {@code factory} transformer 044 * @throws NullPointerException if the factory is null 045 */ 046 public static <I, O> Transformer<I, O> factoryTransformer(final Factory<? extends O> factory) { 047 return new FactoryTransformer<>(Objects.requireNonNull(factory, "factory")); 048 } 049 050 /** The factory to wrap */ 051 private final Factory<? extends R> iFactory; 052 053 /** 054 * Constructor that performs no validation. 055 * Use {@code factoryTransformer} if you want that. 056 * 057 * @param factory the factory to call, not null 058 */ 059 public FactoryTransformer(final Factory<? extends R> factory) { 060 iFactory = factory; 061 } 062 063 /** 064 * Gets the factory. 065 * 066 * @return the factory 067 * @since 3.1 068 */ 069 public Factory<? extends R> getFactory() { 070 return iFactory; 071 } 072 073 /** 074 * Transforms the input by ignoring the input and returning the result of 075 * calling the decorated factory. 076 * 077 * @param input the input object to transform 078 * @return the transformed result 079 */ 080 @Override 081 public R transform(final T input) { 082 return iFactory.get(); 083 } 084 085}