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.functors; 18 19 import java.io.Serializable; 20 21 import org.apache.commons.collections4.Factory; 22 import org.apache.commons.collections4.FunctorException; 23 24 /** 25 * Factory implementation that always throws an exception. 26 * 27 * @since 3.0 28 */ 29 public final class ExceptionFactory<T> implements Factory<T>, Serializable { 30 31 /** Serial version UID */ 32 private static final long serialVersionUID = 7179106032121985545L; 33 34 /** Singleton predicate instance */ 35 @SuppressWarnings("rawtypes") // the static instance works for all types 36 public static final Factory INSTANCE = new ExceptionFactory<>(); 37 38 /** 39 * Factory returning the singleton instance. 40 * 41 * @param <T> the type the factory creates 42 * @return the singleton instance 43 * @since 3.1 44 */ 45 public static <T> Factory<T> exceptionFactory() { 46 return INSTANCE; 47 } 48 49 /** 50 * Restricted constructor. 51 */ 52 private ExceptionFactory() { 53 } 54 55 /** 56 * Always throws an exception. 57 * 58 * @return never 59 * @throws FunctorException always 60 */ 61 @Override 62 public T create() { 63 throw new FunctorException("ExceptionFactory invoked"); 64 } 65 66 private Object readResolve() { 67 return INSTANCE; 68 } 69 70 }