001/**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018
019package org.apache.hadoop.conf;
020
021
022/**
023 * Exception indicating that configuration property cannot be changed
024 * at run time.
025 */
026public class ReconfigurationException extends Exception {
027
028  private static final long serialVersionUID = 1L;
029
030  private String property;
031  private String newVal;
032  private String oldVal;
033
034  /**
035   * Construct the exception message.
036   */
037  private static String constructMessage(String property, 
038                                         String newVal, String oldVal) {
039    String message = "Could not change property " + property;
040    if (oldVal != null) {
041      message += " from \'" + oldVal;
042    }
043    if (newVal != null) {
044      message += "\' to \'" + newVal + "\'";
045    }
046    return message;
047  }
048
049  
050  /**
051   * Create a new instance of {@link ReconfigurationException}.
052   */
053  public ReconfigurationException() {
054    super("Could not change configuration.");
055    this.property = null;
056    this.newVal = null;
057    this.oldVal = null;
058  }
059
060  /**
061   * Create a new instance of {@link ReconfigurationException}.
062   */
063  public ReconfigurationException(String property, 
064                                  String newVal, String oldVal,
065                                  Throwable cause) {
066    super(constructMessage(property, newVal, oldVal), cause);
067    this.property = property;
068    this.newVal = newVal;
069    this.oldVal = oldVal;
070  }
071
072  /**
073   * Create a new instance of {@link ReconfigurationException}.
074   */
075  public ReconfigurationException(String property, 
076                                  String newVal, String oldVal) {
077    super(constructMessage(property, newVal, oldVal));
078    this.property = property;
079    this.newVal = newVal;
080    this.oldVal = oldVal;
081  }
082
083  /**
084   * Get property that cannot be changed.
085   */
086  public String getProperty() {
087    return property;
088  }
089
090  /**
091   * Get value to which property was supposed to be changed.
092   */
093  public String getNewValue() {
094    return newVal;
095  }
096
097  /**
098   * Get old value of property that cannot be changed.
099   */
100  public String getOldValue() {
101    return oldVal;
102  }
103
104}