1 | /*
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2 | * Licensed to the Apache Software Foundation (ASF) under one or more
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3 | * contributor license agreements. See the NOTICE file distributed with
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4 | * this work for additional information regarding copyright ownership.
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5 | * The ASF licenses this file to You under the Apache License, Version 2.0
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6 | * (the "License"); you may not use this file except in compliance with
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7 | * the License. You may obtain a copy of the License at
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8 | *
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9 | * http://www.apache.org/licenses/LICENSE-2.0
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10 | *
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11 | * Unless required by applicable law or agreed to in writing, software
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12 | * distributed under the License is distributed on an "AS IS" BASIS,
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13 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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14 | * See the License for the specific language governing permissions and
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15 | * limitations under the License.
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16 | */
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17 | package agents.org.apache.commons.lang.exception;
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18 |
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19 | import java.io.PrintStream;
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20 | import java.io.PrintWriter;
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21 | import java.io.Serializable;
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22 | import java.io.StringWriter;
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23 | import java.util.ArrayList;
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24 | import java.util.Arrays;
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25 | import java.util.Collections;
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26 | import java.util.Iterator;
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27 | import java.util.List;
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28 |
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29 | /**
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30 | * <p>A shared implementation of the nestable exception functionality.</p>
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31 | * <p>
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32 | * The code is shared between
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33 | * {@link agents.org.apache.commons.lang.exception.NestableError NestableError},
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34 | * {@link agents.org.apache.commons.lang.exception.NestableException NestableException} and
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35 | * {@link agents.org.apache.commons.lang.exception.NestableRuntimeException NestableRuntimeException}.
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36 | * </p>
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37 | *
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38 | * @author Apache Software Foundation
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39 | * @author <a href="mailto:Rafal.Krzewski@e-point.pl">Rafal Krzewski</a>
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40 | * @author Daniel L. Rall
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41 | * @author <a href="mailto:knielsen@apache.org">Kasper Nielsen</a>
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42 | * @author <a href="mailto:steven@caswell.name">Steven Caswell</a>
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43 | * @author Sean C. Sullivan
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44 | * @since 1.0
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45 | * @version $Id: NestableDelegate.java 905636 2010-02-02 14:03:32Z niallp $
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46 | */
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47 | public class NestableDelegate implements Serializable {
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48 |
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49 | /**
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50 | * Required for serialization support.
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51 | *
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52 | * @see java.io.Serializable
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53 | */
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54 | private static final long serialVersionUID = 1L;
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55 |
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56 | /**
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57 | * Constructor error message.
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58 | */
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59 | private transient static final String MUST_BE_THROWABLE =
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60 | "The Nestable implementation passed to the NestableDelegate(Nestable) "
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61 | + "constructor must extend java.lang.Throwable";
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62 |
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63 | /**
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64 | * Holds the reference to the exception or error that we're
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65 | * wrapping (which must be a {@link
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66 | * agents.org.apache.commons.lang.exception.Nestable} implementation).
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67 | */
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68 | private Throwable nestable = null;
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69 |
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70 | /**
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71 | * Whether to print the stack trace top-down.
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72 | * This public flag may be set by calling code, typically in initialisation.
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73 | * This exists for backwards compatability, setting it to false will return
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74 | * the library to v1.0 behaviour (but will affect all users of the library
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75 | * in the classloader).
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76 | * @since 2.0
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77 | */
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78 | public static boolean topDown = true;
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79 |
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80 | /**
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81 | * Whether to trim the repeated stack trace.
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82 | * This public flag may be set by calling code, typically in initialisation.
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83 | * This exists for backwards compatability, setting it to false will return
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84 | * the library to v1.0 behaviour (but will affect all users of the library
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85 | * in the classloader).
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86 | * @since 2.0
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87 | */
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88 | public static boolean trimStackFrames = true;
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89 |
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90 | /**
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91 | * Whether to match subclasses via indexOf.
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92 | * This public flag may be set by calling code, typically in initialisation.
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93 | * This exists for backwards compatability, setting it to false will return
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94 | * the library to v2.0 behaviour (but will affect all users of the library
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95 | * in the classloader).
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96 | * @since 2.1
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97 | */
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98 | public static boolean matchSubclasses = true;
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99 |
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100 | /**
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101 | * Constructs a new <code>NestableDelegate</code> instance to manage the
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102 | * specified <code>Nestable</code>.
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103 | *
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104 | * @param nestable the Nestable implementation (<i>must</i> extend
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105 | * {@link java.lang.Throwable})
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106 | * @since 2.0
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107 | */
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108 | public NestableDelegate(Nestable nestable) {
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109 | if (nestable instanceof Throwable) {
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110 | this.nestable = (Throwable) nestable;
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111 | } else {
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112 | throw new IllegalArgumentException(MUST_BE_THROWABLE);
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113 | }
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114 | }
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115 |
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116 | /**
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117 | * Returns the error message of the <code>Throwable</code> in the chain of <code>Throwable</code>s at the
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118 | * specified index, numbered from 0.
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119 | *
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120 | * @param index
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121 | * the index of the <code>Throwable</code> in the chain of <code>Throwable</code>s
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122 | * @return the error message, or null if the <code>Throwable</code> at the specified index in the chain does not
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123 | * contain a message
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124 | * @throws IndexOutOfBoundsException
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125 | * if the <code>index</code> argument is negative or not less than the count of <code>Throwable</code>s
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126 | * in the chain
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127 | * @since 2.0
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128 | */
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129 | public String getMessage(int index) {
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130 | Throwable t = this.getThrowable(index);
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131 | if (Nestable.class.isInstance(t)) {
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132 | return ((Nestable) t).getMessage(0);
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133 | }
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134 | return t.getMessage();
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135 | }
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136 |
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137 | /**
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138 | * Returns the full message contained by the <code>Nestable</code> and any nested <code>Throwable</code>s.
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139 | *
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140 | * @param baseMsg
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141 | * the base message to use when creating the full message. Should be generally be called via
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142 | * <code>nestableHelper.getMessage(super.getMessage())</code>, where <code>super</code> is an
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143 | * instance of {@link java.lang.Throwable}.
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144 | * @return The concatenated message for this and all nested <code>Throwable</code>s
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145 | * @since 2.0
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146 | */
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147 | public String getMessage(String baseMsg) {
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148 | Throwable nestedCause = ExceptionUtils.getCause(this.nestable);
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149 | String causeMsg = nestedCause == null ? null : nestedCause.getMessage();
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150 | if (nestedCause == null || causeMsg == null) {
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151 | return baseMsg; // may be null, which is a valid result
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152 | }
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153 | if (baseMsg == null) {
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154 | return causeMsg;
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155 | }
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156 | return baseMsg + ": " + causeMsg;
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157 | }
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158 |
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159 | /**
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160 | * Returns the error message of this and any nested <code>Throwable</code>s in an array of Strings, one element
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161 | * for each message. Any <code>Throwable</code> not containing a message is represented in the array by a null.
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162 | * This has the effect of cause the length of the returned array to be equal to the result of the
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163 | * {@link #getThrowableCount()} operation.
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164 | *
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165 | * @return the error messages
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166 | * @since 2.0
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167 | */
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168 | public String[] getMessages() {
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169 | Throwable[] throwables = this.getThrowables();
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170 | String[] msgs = new String[throwables.length];
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171 | for (int i = 0; i < throwables.length; i++) {
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172 | msgs[i] =
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173 | (Nestable.class.isInstance(throwables[i])
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174 | ? ((Nestable) throwables[i]).getMessage(0)
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175 | : throwables[i].getMessage());
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176 | }
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177 | return msgs;
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178 | }
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179 |
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180 | /**
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181 | * Returns the <code>Throwable</code> in the chain of
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182 | * <code>Throwable</code>s at the specified index, numbered from 0.
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183 | *
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184 | * @param index the index, numbered from 0, of the <code>Throwable</code> in
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185 | * the chain of <code>Throwable</code>s
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186 | * @return the <code>Throwable</code>
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187 | * @throws IndexOutOfBoundsException if the <code>index</code> argument is
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188 | * negative or not less than the count of <code>Throwable</code>s in the
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189 | * chain
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190 | * @since 2.0
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191 | */
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192 | public Throwable getThrowable(int index) {
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193 | if (index == 0) {
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194 | return this.nestable;
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195 | }
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196 | Throwable[] throwables = this.getThrowables();
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197 | return throwables[index];
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198 | }
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199 |
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200 | /**
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201 | * Returns the number of <code>Throwable</code>s contained in the
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202 | * <code>Nestable</code> contained by this delegate.
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203 | *
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204 | * @return the throwable count
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205 | * @since 2.0
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206 | */
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207 | public int getThrowableCount() {
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208 | return ExceptionUtils.getThrowableCount(this.nestable);
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209 | }
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210 |
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211 | /**
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212 | * Returns this delegate's <code>Nestable</code> and any nested
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213 | * <code>Throwable</code>s in an array of <code>Throwable</code>s, one
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214 | * element for each <code>Throwable</code>.
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215 | *
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216 | * @return the <code>Throwable</code>s
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217 | * @since 2.0
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218 | */
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219 | public Throwable[] getThrowables() {
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220 | return ExceptionUtils.getThrowables(this.nestable);
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221 | }
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222 |
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223 | /**
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224 | * Returns the index, numbered from 0, of the first <code>Throwable</code>
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225 | * that matches the specified type, or a subclass, in the chain of <code>Throwable</code>s
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226 | * with an index greater than or equal to the specified index.
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227 | * The method returns -1 if the specified type is not found in the chain.
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228 | * <p>
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229 | * NOTE: From v2.1, we have clarified the <code>Nestable</code> interface
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230 | * such that this method matches subclasses.
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231 | * If you want to NOT match subclasses, please use
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232 | * {@link ExceptionUtils#indexOfThrowable(Throwable, Class, int)}
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233 | * (which is avaiable in all versions of lang).
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234 | * An alternative is to use the public static flag {@link #matchSubclasses}
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235 | * on <code>NestableDelegate</code>, however this is not recommended.
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236 | *
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237 | * @param type the type to find, subclasses match, null returns -1
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238 | * @param fromIndex the index, numbered from 0, of the starting position in
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239 | * the chain to be searched
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240 | * @return index of the first occurrence of the type in the chain, or -1 if
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241 | * the type is not found
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242 | * @throws IndexOutOfBoundsException if the <code>fromIndex</code> argument
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243 | * is negative or not less than the count of <code>Throwable</code>s in the
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244 | * chain
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245 | * @since 2.0
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246 | */
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247 | public int indexOfThrowable(Class type, int fromIndex) {
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248 | if (type == null) {
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249 | return -1;
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250 | }
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251 | if (fromIndex < 0) {
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252 | throw new IndexOutOfBoundsException("The start index was out of bounds: " + fromIndex);
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253 | }
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254 | Throwable[] throwables = ExceptionUtils.getThrowables(this.nestable);
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255 | if (fromIndex >= throwables.length) {
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256 | throw new IndexOutOfBoundsException("The start index was out of bounds: "
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257 | + fromIndex + " >= " + throwables.length);
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258 | }
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259 | if (matchSubclasses) {
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260 | for (int i = fromIndex; i < throwables.length; i++) {
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261 | if (type.isAssignableFrom(throwables[i].getClass())) {
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262 | return i;
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263 | }
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264 | }
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265 | } else {
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266 | for (int i = fromIndex; i < throwables.length; i++) {
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267 | if (type.equals(throwables[i].getClass())) {
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268 | return i;
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269 | }
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270 | }
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271 | }
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272 | return -1;
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273 | }
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274 |
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275 | /**
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276 | * Prints the stack trace of this exception the the standar error
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277 | * stream.
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278 | */
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279 | public void printStackTrace() {
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280 | printStackTrace(System.err);
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281 | }
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282 |
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283 | /**
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284 | * Prints the stack trace of this exception to the specified
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285 | * stream.
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286 | *
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287 | * @param out <code>PrintStream</code> to use for output.
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288 | * @see #printStackTrace(PrintWriter)
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289 | */
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290 | public void printStackTrace(PrintStream out) {
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291 | synchronized (out) {
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292 | PrintWriter pw = new PrintWriter(out, false);
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293 | printStackTrace(pw);
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294 | // Flush the PrintWriter before it's GC'ed.
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295 | pw.flush();
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296 | }
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297 | }
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298 |
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299 | /**
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300 | * Prints the stack trace of this exception to the specified
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301 | * writer. If the Throwable class has a <code>getCause</code>
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302 | * method (i.e. running on jre1.4 or higher), this method just
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303 | * uses Throwable's printStackTrace() method. Otherwise, generates
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304 | * the stack-trace, by taking into account the 'topDown' and
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305 | * 'trimStackFrames' parameters. The topDown and trimStackFrames
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306 | * are set to 'true' by default (produces jre1.4-like stack trace).
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307 | *
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308 | * @param out <code>PrintWriter</code> to use for output.
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309 | */
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310 | public void printStackTrace(PrintWriter out) {
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311 | Throwable throwable = this.nestable;
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312 | // if running on jre1.4 or higher, use default printStackTrace
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313 | if (ExceptionUtils.isThrowableNested()) {
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314 | if (throwable instanceof Nestable) {
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315 | ((Nestable)throwable).printPartialStackTrace(out);
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316 | } else {
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317 | throwable.printStackTrace(out);
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318 | }
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319 | return;
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320 | }
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321 |
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322 | // generating the nested stack trace
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323 | List stacks = new ArrayList();
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324 | while (throwable != null) {
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325 | String[] st = getStackFrames(throwable);
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326 | stacks.add(st);
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327 | throwable = ExceptionUtils.getCause(throwable);
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328 | }
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329 |
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330 | // If NOT topDown, reverse the stack
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331 | String separatorLine = "Caused by: ";
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332 | if (!topDown) {
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333 | separatorLine = "Rethrown as: ";
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334 | Collections.reverse(stacks);
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335 | }
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336 |
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337 | // Remove the repeated lines in the stack
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338 | if (trimStackFrames) {
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339 | trimStackFrames(stacks);
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340 | }
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341 |
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342 | synchronized (out) {
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343 | for (Iterator iter=stacks.iterator(); iter.hasNext();) {
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344 | String[] st = (String[]) iter.next();
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345 | for (int i=0, len=st.length; i < len; i++) {
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346 | out.println(st[i]);
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347 | }
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348 | if (iter.hasNext()) {
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349 | out.print(separatorLine);
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350 | }
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351 | }
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352 | }
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353 | }
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354 |
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355 | /**
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356 | * Captures the stack trace associated with the specified
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357 | * <code>Throwable</code> object, decomposing it into a list of
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358 | * stack frames.
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359 | *
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360 | * @param t The <code>Throwable</code>.
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361 | * @return An array of strings describing each stack frame.
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362 | * @since 2.0
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363 | */
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364 | protected String[] getStackFrames(Throwable t) {
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365 | StringWriter sw = new StringWriter();
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366 | PrintWriter pw = new PrintWriter(sw, true);
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367 |
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368 | // Avoid infinite loop between decompose() and printStackTrace().
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369 | if (t instanceof Nestable) {
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370 | ((Nestable) t).printPartialStackTrace(pw);
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371 | } else {
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372 | t.printStackTrace(pw);
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373 | }
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374 | return ExceptionUtils.getStackFrames(sw.getBuffer().toString());
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375 | }
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376 |
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377 | /**
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378 | * Trims the stack frames. The first set is left untouched. The rest
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379 | * of the frames are truncated from the bottom by comparing with
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380 | * one just on top.
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381 | *
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382 | * @param stacks The list containing String[] elements
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383 | * @since 2.0
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384 | */
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385 | protected void trimStackFrames(List stacks) {
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386 | for (int size=stacks.size(), i=size-1; i > 0; i--) {
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387 | String[] curr = (String[]) stacks.get(i);
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388 | String[] next = (String[]) stacks.get(i-1);
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389 |
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390 | List currList = new ArrayList(Arrays.asList(curr));
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391 | List nextList = new ArrayList(Arrays.asList(next));
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392 | ExceptionUtils.removeCommonFrames(currList, nextList);
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393 |
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394 | int trimmed = curr.length - currList.size();
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395 | if (trimmed > 0) {
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396 | currList.add("\t... "+trimmed+" more");
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397 | stacks.set(
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398 | i,
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399 | currList.toArray(new String[currList.size()])
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400 | );
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401 | }
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402 | }
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403 | }
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404 | }
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