/*
* 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.Closure;
import org.apache.commons.collections4.FunctorException;
/**
* Closure implementation that always throws an exception.
*
* @since 3.0
* @version $Id$
*/
public final class ExceptionClosure<E> implements Closure<E>, 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 Closure INSTANCE = new ExceptionClosure<Object>();
/**
* Factory returning the singleton instance.
*
* @param <E> the type that the closure acts on
* @return the singleton instance
* @since 3.1
*/
@SuppressWarnings("unchecked") // the static instance works for all types
public static <E> Closure<E> exceptionClosure() {
return (Closure<E>) INSTANCE;
}
/**
* Restricted constructor.
*/
private ExceptionClosure() {
super();
}
/**
* Always throw an exception.
*
* @param input the input object
* @throws FunctorException always
*/
public void execute(final E input) {
throw new FunctorException("ExceptionClosure invoked");
}
private Object readResolve() {
return INSTANCE;
}
}