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    
019    package org.apache.hadoop.conf;
020    
021    
022    /**
023     * Exception indicating that configuration property cannot be changed
024     * at run time.
025     */
026    public 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    }