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 */
017 package org.apache.commons.lang;
018
019 /**
020 * <p>Thrown when an object is an instance of an unexpected type (a class or interface).
021 * This exception supplements the standard <code>IllegalArgumentException</code>
022 * by providing a more semantically rich description of the problem.</p>
023 *
024 * <p><code>IllegalClassException</code> represents the case where a method takes
025 * in a genericly typed parameter like Object (typically because it has to due to some
026 * other interface it implements), but this implementation only actually accepts a specific
027 * type, for example String. This exception would be used in place of
028 * <code>IllegalArgumentException</code>, yet it still extends it.</p>
029 *
030 * <pre>
031 * public void foo(Object obj) {
032 * if (obj instanceof String == false) {
033 * throw new IllegalClassException(String.class, obj);
034 * }
035 * // do something with the string
036 * }
037 * </pre>
038 *
039 * @author Apache Software Foundation
040 * @author Matthew Hawthorne
041 * @author Gary Gregory
042 * @since 2.0
043 * @version $Id: IllegalClassException.java 905636 2010-02-02 14:03:32Z niallp $
044 */
045 public class IllegalClassException extends IllegalArgumentException {
046
047 /**
048 * Required for serialization support.
049 *
050 * @see java.io.Serializable
051 */
052 private static final long serialVersionUID = 8063272569377254819L;
053
054 /**
055 * <p>Instantiates with the expected type, and actual object.</p>
056 *
057 * @param expected the expected type
058 * @param actual the actual object
059 * @since 2.1
060 */
061 public IllegalClassException(Class expected, Object actual) {
062 super(
063 "Expected: "
064 + safeGetClassName(expected)
065 + ", actual: "
066 + (actual == null ? "null" : actual.getClass().getName()));
067 }
068
069 /**
070 * <p>Instantiates with the expected and actual types.</p>
071 *
072 * @param expected the expected type
073 * @param actual the actual type
074 */
075 public IllegalClassException(Class expected, Class actual) {
076 super(
077 "Expected: "
078 + safeGetClassName(expected)
079 + ", actual: "
080 + safeGetClassName(actual));
081 }
082
083 /**
084 * <p>Instantiates with the specified message.</p>
085 *
086 * @param message the exception message
087 */
088 public IllegalClassException(String message) {
089 super(message);
090 }
091
092 /**
093 * <p>Returns the class name or <code>null</code> if the class is
094 * <code>null</code>.</p>
095 *
096 * @param cls a <code>Class</code>
097 * @return the name of <code>cls</code>, or <code>null</code> if if <code>cls</code> is <code>null</code>.
098 */
099 private static final String safeGetClassName(Class cls) {
100 return cls == null ? null : cls.getName();
101 }
102
103 }