001 /*
002 * Copyright 2003-2004 The Apache Software Foundation
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016 package org.apache.commons.convert1.string;
017
018
019 import org.apache.commons.convert1.ConversionException;
020 import org.apache.commons.convert1.Converter;
021
022
023 /**
024 * <p>Standard {@link Converter} implementation that converts an incoming
025 * String into a <code>java.lang.Character</code> object, optionally using a
026 * default value or throwing a {@link ConversionException} if a conversion
027 * error occurs.</p>
028 *
029 * @author Craig R. McClanahan
030 * @version $Id: CharacterConverter.java 155441 2005-02-26 13:19:22Z dirkv $
031 * @since 0.1
032 */
033
034 public final class CharacterConverter implements Converter {
035
036
037 // ----------------------------------------------------------- Constructors
038
039
040 /**
041 * Create a {@link Converter} that will throw a {@link ConversionException}
042 * if a conversion error occurs.
043 */
044 public CharacterConverter() {
045
046 this.defaultValue = null;
047 this.useDefault = false;
048
049 }
050
051
052 /**
053 * Create a {@link Converter} that will return the specified default value
054 * if a conversion error occurs.
055 *
056 * @param defaultValue The default value to be returned
057 */
058 public CharacterConverter(Object defaultValue) {
059
060 this.defaultValue = defaultValue;
061 this.useDefault = true;
062
063 }
064
065
066 // ----------------------------------------------------- Instance Variables
067
068
069 /**
070 * The default value specified to our Constructor, if any.
071 */
072 private Object defaultValue = null;
073
074
075 /**
076 * Should we return the default value on conversion errors?
077 */
078 private boolean useDefault = true;
079
080
081 // --------------------------------------------------------- Public Methods
082
083
084 /**
085 * Convert the specified input object into an output object of the
086 * specified type.
087 *
088 * @param type Data type to which this value should be converted
089 * @param value The input value to be converted
090 *
091 * @exception ConversionException if conversion cannot be performed
092 * successfully
093 */
094 public Object convert(Class type, Object value) {
095
096 if (value == null) {
097 if (useDefault) {
098 return (defaultValue);
099 } else {
100 throw new ConversionException("No value specified");
101 }
102 }
103
104 if (value instanceof Character) {
105 return (value);
106 }
107
108 try {
109 return (new Character(value.toString().charAt(0)));
110 } catch (Exception e) {
111 if (useDefault) {
112 return (defaultValue);
113 } else {
114 throw new ConversionException(e);
115 }
116 }
117
118 }
119
120
121 }