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; 020 021import org.apache.commons.collections4.Factory; 022import org.apache.commons.collections4.Transformer; 023 024/** 025 * Transformer implementation that calls a Factory and returns the result. 026 * 027 * @since 3.0 028 */ 029public class FactoryTransformer<I, O> implements Transformer<I, O>, Serializable { 030 031 /** Serial version UID */ 032 private static final long serialVersionUID = -6817674502475353160L; 033 034 /** The factory to wrap */ 035 private final Factory<? extends O> iFactory; 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</code> 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 if (factory == null) { 048 throw new NullPointerException("Factory must not be null"); 049 } 050 return new FactoryTransformer<>(factory); 051 } 052 053 /** 054 * Constructor that performs no validation. 055 * Use <code>factoryTransformer</code> if you want that. 056 * 057 * @param factory the factory to call, not null 058 */ 059 public FactoryTransformer(final Factory<? extends O> factory) { 060 super(); 061 iFactory = factory; 062 } 063 064 /** 065 * Transforms the input by ignoring the input and returning the result of 066 * calling the decorated factory. 067 * 068 * @param input the input object to transform 069 * @return the transformed result 070 */ 071 @Override 072 public O transform(final I input) { 073 return iFactory.create(); 074 } 075 076 /** 077 * Gets the factory. 078 * 079 * @return the factory 080 * @since 3.1 081 */ 082 public Factory<? extends O> getFactory() { 083 return iFactory; 084 } 085 086}