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.juneau.internal;
018
019import static org.apache.juneau.common.utils.StringUtils.*;
020import static org.apache.juneau.common.utils.ThrowableUtils.*;
021
022/**
023 * Builder class for {@link Exception} objects.
024 *
025 * <h5 class='section'>See Also:</h5><ul>
026 * </ul>
027 *
028 * @param <T> The exception class.
029 */
030public class ExceptionBuilder<T extends Throwable> {
031
032   private final Class<T> type;
033   private String message;
034   private Throwable causedBy;
035
036   /**
037    * Default constructor.
038    * @param type The exception type to create.
039    */
040   public ExceptionBuilder(Class<T> type) {
041      this.type = type;
042   }
043
044   /**
045    * Specifies the exception message.
046    *
047    * @param msg The exception message.  Can be <jk>null</jk>.
048    *    <br>If <jk>null</jk>, then the caused-by message is used if available.
049    * @param args The exception message arguments.
050    * @return This object.
051    */
052   public ExceptionBuilder<T> message(String msg, Object...args) {
053      message = format(msg, args);
054      return this;
055   }
056
057   /**
058    * Specifies the caused-by exception.
059    *
060    * @param value The caused-by exception.  Can be <jk>null</jk>.
061    * @return This object.
062    */
063   public ExceptionBuilder<T> causedBy(Throwable value) {
064      causedBy = value;
065      return this;
066   }
067   /**
068    * Creates the exception.
069    *
070    * @return The exception.
071    */
072   public T build() {
073      try {
074         return type.getConstructor(String.class, Throwable.class).newInstance(message, causedBy);
075      } catch (Exception e) {
076         throw asRuntimeException(e);
077      }
078   }
079}