ExceptionTransformer.java
- /*
- * 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.functors;
- import java.io.Serializable;
- import org.apache.commons.collections4.FunctorException;
- import org.apache.commons.collections4.Transformer;
- /**
- * Transformer implementation that always throws an exception.
- *
- * @param <T> the type of the input to the function.
- * @param <R> the type of the result of the function.
- * @since 3.0
- */
- public final class ExceptionTransformer<T, R> implements Transformer<T, R>, Serializable {
- /** Serial version UID */
- private static final long serialVersionUID = 7179106032121985545L;
- /** Singleton predicate instance */
- @SuppressWarnings("rawtypes") // the static instance works for all types
- public static final Transformer INSTANCE = new ExceptionTransformer<>();
- /**
- * Factory returning the singleton instance.
- *
- * @param <I> the input type
- * @param <O> the output type
- * @return the singleton instance
- * @since 3.1
- */
- public static <I, O> Transformer<I, O> exceptionTransformer() {
- return INSTANCE;
- }
- /**
- * Restricted constructor.
- */
- private ExceptionTransformer() {
- }
- /**
- * Returns the singleton instance.
- *
- * @return the singleton instance.
- */
- private Object readResolve() {
- return INSTANCE;
- }
- /**
- * Transforms the input to result by cloning it.
- *
- * @param input the input object to transform
- * @return never
- * @throws FunctorException always
- */
- @Override
- public R transform(final T input) {
- throw new FunctorException("ExceptionTransformer invoked");
- }
- }