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.beanutils2.converters;
018
019/**
020 * {@link org.apache.commons.beanutils2.Converter} implementation that handles conversion to and from <strong>java.lang.Enum</strong> objects.
021 * <p>
022 * Can be configured to either return a <em>default value</em> or throw a {@code ConversionException} if a conversion error occurs.
023 * </p>
024 *
025 * @param <E> The enum type subclass
026 * @since 2.0
027 * @see Enum
028 */
029public final class EnumConverter<E extends Enum<E>> extends AbstractConverter<Enum<E>> {
030
031    /**
032     * Constructs a <strong>java.lang.Enum</strong> <em>Converter</em> that throws a {@code ConversionException} if an error occurs.
033     */
034    public EnumConverter() {
035    }
036
037    /**
038     * Constructs a <strong>java.lang.Enum</strong> <em>Converter</em> that returns a default value if an error occurs.
039     *
040     * @param defaultValue The default value to be returned if the value to be converted is missing or an error occurs converting the value.
041     */
042    public EnumConverter(final Enum<E> defaultValue) {
043        super(defaultValue);
044    }
045
046    /**
047     * <p>
048     * Converts a java.lang.Enum or object into a String.
049     * </p>
050     *
051     * @param <R>   Target type of the conversion.
052     * @param type  Data type to which this value should be converted.
053     * @param value The input value to be converted.
054     * @return The converted value.
055     * @throws Throwable if an error occurs converting to the specified type
056     * @since 2.0
057     */
058    @SuppressWarnings({ "rawtypes" })
059    @Override
060    protected <R> R convertToType(final Class<R> type, final Object value) throws Throwable {
061        if (Enum.class.isAssignableFrom(type)) {
062            final String enumValue = String.valueOf(value);
063            final R[] constants = type.getEnumConstants();
064            if (constants == null) {
065                throw conversionException(type, value);
066            }
067            for (final R candidate : constants) {
068                if (((Enum) candidate).name().equalsIgnoreCase(enumValue)) {
069                    return candidate;
070                }
071            }
072        }
073
074        throw conversionException(type, value);
075    }
076
077    /**
078     * Gets the default type this {@code Converter} handles.
079     *
080     * @return The default type this {@code Converter} handles.
081     * @since 2.0
082     */
083    @SuppressWarnings({ "unchecked", "rawtypes" })
084    @Override
085    protected Class<Enum<E>> getDefaultType() {
086        return (Class) Enum.class;
087    }
088
089}