Coverage Report - org.apache.commons.lang3.exception.ExceptionUtils
 
Classes in this File Line Coverage Branch Coverage Complexity
ExceptionUtils
90%
141/156
93%
88/94
3,483
 
 1  
 /*
 2  
  * Licensed to the Apache Software Foundation (ASF) under one or more
 3  
  * contributor license agreements.  See the NOTICE file distributed with
 4  
  * this work for additional information regarding copyright ownership.
 5  
  * The ASF licenses this file to You under the Apache License, Version 2.0
 6  
  * (the "License"); you may not use this file except in compliance with
 7  
  * the License.  You may obtain a copy of the License at
 8  
  * 
 9  
  *      http://www.apache.org/licenses/LICENSE-2.0
 10  
  * 
 11  
  * Unless required by applicable law or agreed to in writing, software
 12  
  * distributed under the License is distributed on an "AS IS" BASIS,
 13  
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 14  
  * See the License for the specific language governing permissions and
 15  
  * limitations under the License.
 16  
  */
 17  
 package org.apache.commons.lang3.exception;
 18  
 
 19  
 import java.io.PrintStream;
 20  
 import java.io.PrintWriter;
 21  
 import java.io.StringWriter;
 22  
 import java.lang.reflect.InvocationTargetException;
 23  
 import java.lang.reflect.Method;
 24  
 import java.lang.reflect.UndeclaredThrowableException;
 25  
 import java.util.ArrayList;
 26  
 import java.util.List;
 27  
 import java.util.StringTokenizer;
 28  
 
 29  
 import org.apache.commons.lang3.ArrayUtils;
 30  
 import org.apache.commons.lang3.ClassUtils;
 31  
 import org.apache.commons.lang3.StringUtils;
 32  
 import org.apache.commons.lang3.SystemUtils;
 33  
 
 34  
 /**
 35  
  * <p>Provides utilities for manipulating and examining 
 36  
  * <code>Throwable</code> objects.</p>
 37  
  *
 38  
  * @since 1.0
 39  
  */
 40  
 public class ExceptionUtils {
 41  
     
 42  
     /**
 43  
      * <p>Used when printing stack frames to denote the start of a
 44  
      * wrapped exception.</p>
 45  
      *
 46  
      * <p>Package private for accessibility by test suite.</p>
 47  
      */
 48  
     static final String WRAPPED_MARKER = " [wrapped] ";
 49  
 
 50  
     /**
 51  
      * <p>The names of methods commonly used to access a wrapped exception.</p>
 52  
      */
 53  
     // TODO: Remove in Lang 4.0
 54  1
     private static final String[] CAUSE_METHOD_NAMES = {
 55  
         "getCause",
 56  
         "getNextException",
 57  
         "getTargetException",
 58  
         "getException",
 59  
         "getSourceException",
 60  
         "getRootCause",
 61  
         "getCausedByException",
 62  
         "getNested",
 63  
         "getLinkedException",
 64  
         "getNestedException",
 65  
         "getLinkedCause",
 66  
         "getThrowable",
 67  
     };
 68  
 
 69  
     /**
 70  
      * <p>
 71  
      * Public constructor allows an instance of <code>ExceptionUtils</code> to be created, although that is not
 72  
      * normally necessary.
 73  
      * </p>
 74  
      */
 75  
     public ExceptionUtils() {
 76  1
         super();
 77  1
     }
 78  
 
 79  
     //-----------------------------------------------------------------------
 80  
     /**
 81  
      * <p>Returns the default names used when searching for the cause of an exception.</p>
 82  
      *
 83  
      * <p>This may be modified and used in the overloaded getCause(Throwable, String[]) method.</p>
 84  
      *
 85  
      * @return cloned array of the default method names
 86  
      * @since 3.0
 87  
      * @deprecated This feature will be removed in Lang 4.0
 88  
      */
 89  
     @Deprecated
 90  
     public static String[] getDefaultCauseMethodNames() {
 91  0
         return ArrayUtils.clone(CAUSE_METHOD_NAMES);
 92  
     }
 93  
 
 94  
     //-----------------------------------------------------------------------
 95  
     /**
 96  
      * <p>Introspects the <code>Throwable</code> to obtain the cause.</p>
 97  
      *
 98  
      * <p>The method searches for methods with specific names that return a 
 99  
      * <code>Throwable</code> object. This will pick up most wrapping exceptions,
 100  
      * including those from JDK 1.4.
 101  
      *
 102  
      * <p>The default list searched for are:</p>
 103  
      * <ul>
 104  
      *  <li><code>getCause()</code></li>
 105  
      *  <li><code>getNextException()</code></li>
 106  
      *  <li><code>getTargetException()</code></li>
 107  
      *  <li><code>getException()</code></li>
 108  
      *  <li><code>getSourceException()</code></li>
 109  
      *  <li><code>getRootCause()</code></li>
 110  
      *  <li><code>getCausedByException()</code></li>
 111  
      *  <li><code>getNested()</code></li>
 112  
      * </ul>
 113  
      * 
 114  
      * <p>If none of the above is found, returns <code>null</code>.</p>
 115  
      *
 116  
      * @param throwable  the throwable to introspect for a cause, may be null
 117  
      * @return the cause of the <code>Throwable</code>,
 118  
      *  <code>null</code> if none found or null throwable input
 119  
      * @since 1.0
 120  
      * @deprecated This feature will be removed in Lang 4.0, use {@link Throwable#getCause} instead
 121  
      */
 122  
     @Deprecated
 123  
     public static Throwable getCause(final Throwable throwable) {
 124  174
         return getCause(throwable, null);
 125  
     }
 126  
 
 127  
     /**
 128  
      * <p>Introspects the <code>Throwable</code> to obtain the cause.</p>
 129  
      *
 130  
      * <p>A <code>null</code> set of method names means use the default set.
 131  
      * A <code>null</code> in the set of method names will be ignored.</p>
 132  
      *
 133  
      * @param throwable  the throwable to introspect for a cause, may be null
 134  
      * @param methodNames  the method names, null treated as default set
 135  
      * @return the cause of the <code>Throwable</code>,
 136  
      *  <code>null</code> if none found or null throwable input
 137  
      * @since 1.0
 138  
      * @deprecated This feature will be removed in Lang 4.0, use {@link Throwable#getCause} instead
 139  
      */
 140  
     @Deprecated
 141  
     public static Throwable getCause(final Throwable throwable, String[] methodNames) {
 142  185
         if (throwable == null) {
 143  3
             return null;
 144  
         }
 145  
 
 146  182
         if (methodNames == null) {
 147  175
             final Throwable cause = throwable.getCause();
 148  175
             if (cause != null) {
 149  98
                 return cause;
 150  
             }
 151  
 
 152  77
             methodNames = CAUSE_METHOD_NAMES;
 153  
         }
 154  
 
 155  1012
         for (final String methodName : methodNames) {
 156  929
             if (methodName != null) {
 157  927
                 final Throwable legacyCause = getCauseUsingMethodName(throwable, methodName);
 158  927
                 if (legacyCause != null) {
 159  1
                     return legacyCause;
 160  
                 }
 161  
             }
 162  
         }
 163  
 
 164  83
         return null;
 165  
     }
 166  
 
 167  
     /**
 168  
      * <p>Introspects the <code>Throwable</code> to obtain the root cause.</p>
 169  
      *
 170  
      * <p>This method walks through the exception chain to the last element,
 171  
      * "root" of the tree, using {@link #getCause(Throwable)}, and
 172  
      * returns that exception.</p>
 173  
      *
 174  
      * <p>From version 2.2, this method handles recursive cause structures
 175  
      * that might otherwise cause infinite loops. If the throwable parameter
 176  
      * has a cause of itself, then null will be returned. If the throwable
 177  
      * parameter cause chain loops, the last element in the chain before the
 178  
      * loop is returned.</p>
 179  
      *
 180  
      * @param throwable  the throwable to get the root cause for, may be null
 181  
      * @return the root cause of the <code>Throwable</code>,
 182  
      *  <code>null</code> if none found or null throwable input
 183  
      */
 184  
     public static Throwable getRootCause(final Throwable throwable) {
 185  9
         final List<Throwable> list = getThrowableList(throwable);
 186  9
         return list.size() < 2 ? null : (Throwable)list.get(list.size() - 1);
 187  
     }
 188  
 
 189  
     /**
 190  
      * <p>Finds a <code>Throwable</code> by method name.</p>
 191  
      *
 192  
      * @param throwable  the exception to examine
 193  
      * @param methodName  the name of the method to find and invoke
 194  
      * @return the wrapped exception, or <code>null</code> if not found
 195  
      */
 196  
     // TODO: Remove in Lang 4.0
 197  
     private static Throwable getCauseUsingMethodName(final Throwable throwable, final String methodName) {
 198  927
         Method method = null;
 199  
         try {
 200  927
             method = throwable.getClass().getMethod(methodName);
 201  779
         } catch (final NoSuchMethodException ignored) { // NOPMD
 202  
             // exception ignored
 203  0
         } catch (final SecurityException ignored) { // NOPMD
 204  
             // exception ignored
 205  927
         }
 206  
 
 207  927
         if (method != null && Throwable.class.isAssignableFrom(method.getReturnType())) {
 208  
             try {
 209  79
                 return (Throwable) method.invoke(throwable);
 210  0
             } catch (final IllegalAccessException ignored) { // NOPMD
 211  
                 // exception ignored
 212  0
             } catch (final IllegalArgumentException ignored) { // NOPMD
 213  
                 // exception ignored
 214  0
             } catch (final InvocationTargetException ignored) { // NOPMD
 215  
                 // exception ignored
 216  0
             }
 217  
         }
 218  848
         return null;
 219  
     }
 220  
 
 221  
     //-----------------------------------------------------------------------
 222  
     /**
 223  
      * <p>Counts the number of <code>Throwable</code> objects in the
 224  
      * exception chain.</p>
 225  
      *
 226  
      * <p>A throwable without cause will return <code>1</code>.
 227  
      * A throwable with one cause will return <code>2</code> and so on.
 228  
      * A <code>null</code> throwable will return <code>0</code>.</p>
 229  
      *
 230  
      * <p>From version 2.2, this method handles recursive cause structures
 231  
      * that might otherwise cause infinite loops. The cause chain is
 232  
      * processed until the end is reached, or until the next item in the
 233  
      * chain is already in the result set.</p>
 234  
      *
 235  
      * @param throwable  the throwable to inspect, may be null
 236  
      * @return the count of throwables, zero if null input
 237  
      */
 238  
     public static int getThrowableCount(final Throwable throwable) {
 239  8
         return getThrowableList(throwable).size();
 240  
     }
 241  
 
 242  
     /**
 243  
      * <p>Returns the list of <code>Throwable</code> objects in the
 244  
      * exception chain.</p>
 245  
      *
 246  
      * <p>A throwable without cause will return an array containing
 247  
      * one element - the input throwable.
 248  
      * A throwable with one cause will return an array containing
 249  
      * two elements. - the input throwable and the cause throwable.
 250  
      * A <code>null</code> throwable will return an array of size zero.</p>
 251  
      *
 252  
      * <p>From version 2.2, this method handles recursive cause structures
 253  
      * that might otherwise cause infinite loops. The cause chain is
 254  
      * processed until the end is reached, or until the next item in the
 255  
      * chain is already in the result set.</p>
 256  
      *
 257  
      * @see #getThrowableList(Throwable)
 258  
      * @param throwable  the throwable to inspect, may be null
 259  
      * @return the array of throwables, never null
 260  
      */
 261  
     public static Throwable[] getThrowables(final Throwable throwable) {
 262  60
         final List<Throwable> list = getThrowableList(throwable);
 263  60
         return list.toArray(new Throwable[list.size()]);
 264  
     }
 265  
 
 266  
     /**
 267  
      * <p>Returns the list of <code>Throwable</code> objects in the
 268  
      * exception chain.</p>
 269  
      *
 270  
      * <p>A throwable without cause will return a list containing
 271  
      * one element - the input throwable.
 272  
      * A throwable with one cause will return a list containing
 273  
      * two elements. - the input throwable and the cause throwable.
 274  
      * A <code>null</code> throwable will return a list of size zero.</p>
 275  
      *
 276  
      * <p>This method handles recursive cause structures that might
 277  
      * otherwise cause infinite loops. The cause chain is processed until
 278  
      * the end is reached, or until the next item in the chain is already
 279  
      * in the result set.</p>
 280  
      *
 281  
      * @param throwable  the throwable to inspect, may be null
 282  
      * @return the list of throwables, never null
 283  
      * @since Commons Lang 2.2
 284  
      */
 285  
     public static List<Throwable> getThrowableList(Throwable throwable) {
 286  83
         final List<Throwable> list = new ArrayList<Throwable>();
 287  248
         while (throwable != null && list.contains(throwable) == false) {
 288  165
             list.add(throwable);
 289  165
             throwable = ExceptionUtils.getCause(throwable);
 290  
         }
 291  83
         return list;
 292  
     }
 293  
 
 294  
     //-----------------------------------------------------------------------
 295  
     /**
 296  
      * <p>Returns the (zero based) index of the first <code>Throwable</code>
 297  
      * that matches the specified class (exactly) in the exception chain.
 298  
      * Subclasses of the specified class do not match - see
 299  
      * {@link #indexOfType(Throwable, Class)} for the opposite.</p>
 300  
      *
 301  
      * <p>A <code>null</code> throwable returns <code>-1</code>.
 302  
      * A <code>null</code> type returns <code>-1</code>.
 303  
      * No match in the chain returns <code>-1</code>.</p>
 304  
      *
 305  
      * @param throwable  the throwable to inspect, may be null
 306  
      * @param clazz  the class to search for, subclasses do not match, null returns -1
 307  
      * @return the index into the throwable chain, -1 if no match or null input
 308  
      */
 309  
     public static int indexOfThrowable(final Throwable throwable, final Class<?> clazz) {
 310  17
         return indexOf(throwable, clazz, 0, false);
 311  
     }
 312  
 
 313  
     /**
 314  
      * <p>Returns the (zero based) index of the first <code>Throwable</code>
 315  
      * that matches the specified type in the exception chain from
 316  
      * a specified index.
 317  
      * Subclasses of the specified class do not match - see
 318  
      * {@link #indexOfType(Throwable, Class, int)} for the opposite.</p>
 319  
      *
 320  
      * <p>A <code>null</code> throwable returns <code>-1</code>.
 321  
      * A <code>null</code> type returns <code>-1</code>.
 322  
      * No match in the chain returns <code>-1</code>.
 323  
      * A negative start index is treated as zero.
 324  
      * A start index greater than the number of throwables returns <code>-1</code>.</p>
 325  
      *
 326  
      * @param throwable  the throwable to inspect, may be null
 327  
      * @param clazz  the class to search for, subclasses do not match, null returns -1
 328  
      * @param fromIndex  the (zero based) index of the starting position,
 329  
      *  negative treated as zero, larger than chain size returns -1
 330  
      * @return the index into the throwable chain, -1 if no match or null input
 331  
      */
 332  
     public static int indexOfThrowable(final Throwable throwable, final Class<?> clazz, final int fromIndex) {
 333  17
         return indexOf(throwable, clazz, fromIndex, false);
 334  
     }
 335  
 
 336  
     //-----------------------------------------------------------------------
 337  
     /**
 338  
      * <p>Returns the (zero based) index of the first <code>Throwable</code>
 339  
      * that matches the specified class or subclass in the exception chain.
 340  
      * Subclasses of the specified class do match - see
 341  
      * {@link #indexOfThrowable(Throwable, Class)} for the opposite.</p>
 342  
      *
 343  
      * <p>A <code>null</code> throwable returns <code>-1</code>.
 344  
      * A <code>null</code> type returns <code>-1</code>.
 345  
      * No match in the chain returns <code>-1</code>.</p>
 346  
      *
 347  
      * @param throwable  the throwable to inspect, may be null
 348  
      * @param type  the type to search for, subclasses match, null returns -1
 349  
      * @return the index into the throwable chain, -1 if no match or null input
 350  
      * @since 2.1
 351  
      */
 352  
     public static int indexOfType(final Throwable throwable, final Class<?> type) {
 353  17
         return indexOf(throwable, type, 0, true);
 354  
     }
 355  
 
 356  
     /**
 357  
      * <p>Returns the (zero based) index of the first <code>Throwable</code>
 358  
      * that matches the specified type in the exception chain from
 359  
      * a specified index.
 360  
      * Subclasses of the specified class do match - see
 361  
      * {@link #indexOfThrowable(Throwable, Class)} for the opposite.</p>
 362  
      *
 363  
      * <p>A <code>null</code> throwable returns <code>-1</code>.
 364  
      * A <code>null</code> type returns <code>-1</code>.
 365  
      * No match in the chain returns <code>-1</code>.
 366  
      * A negative start index is treated as zero.
 367  
      * A start index greater than the number of throwables returns <code>-1</code>.</p>
 368  
      *
 369  
      * @param throwable  the throwable to inspect, may be null
 370  
      * @param type  the type to search for, subclasses match, null returns -1
 371  
      * @param fromIndex  the (zero based) index of the starting position,
 372  
      *  negative treated as zero, larger than chain size returns -1
 373  
      * @return the index into the throwable chain, -1 if no match or null input
 374  
      * @since 2.1
 375  
      */
 376  
     public static int indexOfType(final Throwable throwable, final Class<?> type, final int fromIndex) {
 377  17
         return indexOf(throwable, type, fromIndex, true);
 378  
     }
 379  
 
 380  
     /**
 381  
      * <p>Worker method for the <code>indexOfType</code> methods.</p>
 382  
      *
 383  
      * @param throwable  the throwable to inspect, may be null
 384  
      * @param type  the type to search for, subclasses match, null returns -1
 385  
      * @param fromIndex  the (zero based) index of the starting position,
 386  
      *  negative treated as zero, larger than chain size returns -1
 387  
      * @param subclass if <code>true</code>, compares with {@link Class#isAssignableFrom(Class)}, otherwise compares
 388  
      * using references
 389  
      * @return index of the <code>type</code> within throwables nested within the specified <code>throwable</code>
 390  
      */
 391  
     private static int indexOf(final Throwable throwable, final Class<?> type, int fromIndex, final boolean subclass) {
 392  68
         if (throwable == null || type == null) {
 393  20
             return -1;
 394  
         }
 395  48
         if (fromIndex < 0) {
 396  2
             fromIndex = 0;
 397  
         }
 398  48
         final Throwable[] throwables = ExceptionUtils.getThrowables(throwable);
 399  48
         if (fromIndex >= throwables.length) {
 400  2
             return -1;
 401  
         }
 402  46
         if (subclass) {
 403  41
             for (int i = fromIndex; i < throwables.length; i++) {
 404  34
                 if (type.isAssignableFrom(throwables[i].getClass())) {
 405  16
                     return i;
 406  
                 }
 407  
             }
 408  
         } else {
 409  47
             for (int i = fromIndex; i < throwables.length; i++) {
 410  38
                 if (type.equals(throwables[i].getClass())) {
 411  14
                     return i;
 412  
                 }
 413  
             }
 414  
         }
 415  16
         return -1;
 416  
     }
 417  
 
 418  
     //-----------------------------------------------------------------------
 419  
     /**
 420  
      * <p>Prints a compact stack trace for the root cause of a throwable
 421  
      * to <code>System.err</code>.</p>
 422  
      *
 423  
      * <p>The compact stack trace starts with the root cause and prints
 424  
      * stack frames up to the place where it was caught and wrapped.
 425  
      * Then it prints the wrapped exception and continues with stack frames
 426  
      * until the wrapper exception is caught and wrapped again, etc.</p>
 427  
      *
 428  
      * <p>The output of this method is consistent across JDK versions.
 429  
      * Note that this is the opposite order to the JDK1.4 display.</p>
 430  
      *
 431  
      * <p>The method is equivalent to <code>printStackTrace</code> for throwables
 432  
      * that don't have nested causes.</p>
 433  
      *
 434  
      * @param throwable  the throwable to output
 435  
      * @since 2.0
 436  
      */
 437  
     public static void printRootCauseStackTrace(final Throwable throwable) {
 438  1
         printRootCauseStackTrace(throwable, System.err);
 439  1
     }
 440  
 
 441  
     /**
 442  
      * <p>Prints a compact stack trace for the root cause of a throwable.</p>
 443  
      *
 444  
      * <p>The compact stack trace starts with the root cause and prints
 445  
      * stack frames up to the place where it was caught and wrapped.
 446  
      * Then it prints the wrapped exception and continues with stack frames
 447  
      * until the wrapper exception is caught and wrapped again, etc.</p>
 448  
      *
 449  
      * <p>The output of this method is consistent across JDK versions.
 450  
      * Note that this is the opposite order to the JDK1.4 display.</p>
 451  
      *
 452  
      * <p>The method is equivalent to <code>printStackTrace</code> for throwables
 453  
      * that don't have nested causes.</p>
 454  
      *
 455  
      * @param throwable  the throwable to output, may be null
 456  
      * @param stream  the stream to output to, may not be null
 457  
      * @throws IllegalArgumentException if the stream is <code>null</code>
 458  
      * @since 2.0
 459  
      */
 460  
     public static void printRootCauseStackTrace(final Throwable throwable, final PrintStream stream) {
 461  6
         if (throwable == null) {
 462  3
             return;
 463  
         }
 464  3
         if (stream == null) {
 465  1
             throw new IllegalArgumentException("The PrintStream must not be null");
 466  
         }
 467  2
         final String trace[] = getRootCauseStackTrace(throwable);
 468  62
         for (final String element : trace) {
 469  60
             stream.println(element);
 470  
         }
 471  2
         stream.flush();
 472  2
     }
 473  
 
 474  
     /**
 475  
      * <p>Prints a compact stack trace for the root cause of a throwable.</p>
 476  
      *
 477  
      * <p>The compact stack trace starts with the root cause and prints
 478  
      * stack frames up to the place where it was caught and wrapped.
 479  
      * Then it prints the wrapped exception and continues with stack frames
 480  
      * until the wrapper exception is caught and wrapped again, etc.</p>
 481  
      *
 482  
      * <p>The output of this method is consistent across JDK versions.
 483  
      * Note that this is the opposite order to the JDK1.4 display.</p>
 484  
      *
 485  
      * <p>The method is equivalent to <code>printStackTrace</code> for throwables
 486  
      * that don't have nested causes.</p>
 487  
      *
 488  
      * @param throwable  the throwable to output, may be null
 489  
      * @param writer  the writer to output to, may not be null
 490  
      * @throws IllegalArgumentException if the writer is <code>null</code>
 491  
      * @since 2.0
 492  
      */
 493  
     public static void printRootCauseStackTrace(final Throwable throwable, final PrintWriter writer) {
 494  5
         if (throwable == null) {
 495  2
             return;
 496  
         }
 497  3
         if (writer == null) {
 498  1
             throw new IllegalArgumentException("The PrintWriter must not be null");
 499  
         }
 500  2
         final String trace[] = getRootCauseStackTrace(throwable);
 501  62
         for (final String element : trace) {
 502  60
             writer.println(element);
 503  
         }
 504  2
         writer.flush();
 505  2
     }
 506  
 
 507  
     //-----------------------------------------------------------------------
 508  
     /**
 509  
      * <p>Creates a compact stack trace for the root cause of the supplied
 510  
      * <code>Throwable</code>.</p>
 511  
      *
 512  
      * <p>The output of this method is consistent across JDK versions.
 513  
      * It consists of the root exception followed by each of its wrapping
 514  
      * exceptions separated by '[wrapped]'. Note that this is the opposite
 515  
      * order to the JDK1.4 display.</p>
 516  
      *
 517  
      * @param throwable  the throwable to examine, may be null
 518  
      * @return an array of stack trace frames, never null
 519  
      * @since 2.0
 520  
      */
 521  
     public static String[] getRootCauseStackTrace(final Throwable throwable) {
 522  7
         if (throwable == null) {
 523  1
             return ArrayUtils.EMPTY_STRING_ARRAY;
 524  
         }
 525  6
         final Throwable throwables[] = getThrowables(throwable);
 526  6
         final int count = throwables.length;
 527  6
         final List<String> frames = new ArrayList<String>();
 528  6
         List<String> nextTrace = getStackFrameList(throwables[count - 1]);
 529  6
         for (int i = count; --i >= 0;) {
 530  12
             final List<String> trace = nextTrace;
 531  12
             if (i != 0) {
 532  6
                 nextTrace = getStackFrameList(throwables[i - 1]);
 533  6
                 removeCommonFrames(trace, nextTrace);
 534  
             }
 535  12
             if (i == count - 1) {
 536  6
                 frames.add(throwables[i].toString());
 537  
             } else {
 538  6
                 frames.add(WRAPPED_MARKER + throwables[i].toString());
 539  
             }
 540  180
             for (int j = 0; j < trace.size(); j++) {
 541  168
                 frames.add(trace.get(j));
 542  
             }
 543  12
         }
 544  6
         return frames.toArray(new String[frames.size()]);
 545  
     }
 546  
 
 547  
     /**
 548  
      * <p>Removes common frames from the cause trace given the two stack traces.</p>
 549  
      *
 550  
      * @param causeFrames  stack trace of a cause throwable
 551  
      * @param wrapperFrames  stack trace of a wrapper throwable
 552  
      * @throws IllegalArgumentException if either argument is null
 553  
      * @since 2.0
 554  
      */
 555  
     public static void removeCommonFrames(final List<String> causeFrames, final List<String> wrapperFrames) {
 556  7
         if (causeFrames == null || wrapperFrames == null) {
 557  1
             throw new IllegalArgumentException("The List must not be null");
 558  
         }
 559  6
         int causeFrameIndex = causeFrames.size() - 1;
 560  6
         int wrapperFrameIndex = wrapperFrames.size() - 1;
 561  174
         while (causeFrameIndex >= 0 && wrapperFrameIndex >= 0) {
 562  
             // Remove the frame from the cause trace if it is the same
 563  
             // as in the wrapper trace
 564  168
             final String causeFrame = causeFrames.get(causeFrameIndex);
 565  168
             final String wrapperFrame = wrapperFrames.get(wrapperFrameIndex);
 566  168
             if (causeFrame.equals(wrapperFrame)) {
 567  165
                 causeFrames.remove(causeFrameIndex);
 568  
             }
 569  168
             causeFrameIndex--;
 570  168
             wrapperFrameIndex--;
 571  168
         }
 572  6
     }
 573  
 
 574  
     //-----------------------------------------------------------------------
 575  
     /**
 576  
      * <p>Gets the stack trace from a Throwable as a String.</p>
 577  
      *
 578  
      * <p>The result of this method vary by JDK version as this method
 579  
      * uses {@link Throwable#printStackTrace(java.io.PrintWriter)}.
 580  
      * On JDK1.3 and earlier, the cause exception will not be shown
 581  
      * unless the specified throwable alters printStackTrace.</p>
 582  
      *
 583  
      * @param throwable  the <code>Throwable</code> to be examined
 584  
      * @return the stack trace as generated by the exception's
 585  
      *  <code>printStackTrace(PrintWriter)</code> method
 586  
      */
 587  
     public static String getStackTrace(final Throwable throwable) {
 588  33
         final StringWriter sw = new StringWriter();
 589  33
         final PrintWriter pw = new PrintWriter(sw, true);
 590  33
         throwable.printStackTrace(pw);
 591  33
         return sw.getBuffer().toString();
 592  
     }
 593  
 
 594  
     /**
 595  
      * <p>Captures the stack trace associated with the specified
 596  
      * <code>Throwable</code> object, decomposing it into a list of
 597  
      * stack frames.</p>
 598  
      *
 599  
      * <p>The result of this method vary by JDK version as this method
 600  
      * uses {@link Throwable#printStackTrace(java.io.PrintWriter)}.
 601  
      * On JDK1.3 and earlier, the cause exception will not be shown
 602  
      * unless the specified throwable alters printStackTrace.</p>
 603  
      *
 604  
      * @param throwable  the <code>Throwable</code> to examine, may be null
 605  
      * @return an array of strings describing each stack frame, never null
 606  
      */
 607  
     public static String[] getStackFrames(final Throwable throwable) {
 608  0
         if (throwable == null) {
 609  0
             return ArrayUtils.EMPTY_STRING_ARRAY;
 610  
         }
 611  0
         return getStackFrames(getStackTrace(throwable));
 612  
     }
 613  
 
 614  
     //-----------------------------------------------------------------------
 615  
     /**
 616  
      * <p>Returns an array where each element is a line from the argument.</p>
 617  
      *
 618  
      * <p>The end of line is determined by the value of {@link SystemUtils#LINE_SEPARATOR}.</p>
 619  
      *
 620  
      * @param stackTrace  a stack trace String
 621  
      * @return an array where each element is a line from the argument
 622  
      */
 623  
     static String[] getStackFrames(final String stackTrace) {
 624  0
         final String linebreak = SystemUtils.LINE_SEPARATOR;
 625  0
         final StringTokenizer frames = new StringTokenizer(stackTrace, linebreak);
 626  0
         final List<String> list = new ArrayList<String>();
 627  0
         while (frames.hasMoreTokens()) {
 628  0
             list.add(frames.nextToken());
 629  
         }
 630  0
         return list.toArray(new String[list.size()]);
 631  
     }
 632  
 
 633  
     /**
 634  
      * <p>Produces a <code>List</code> of stack frames - the message
 635  
      * is not included. Only the trace of the specified exception is
 636  
      * returned, any caused by trace is stripped.</p>
 637  
      *
 638  
      * <p>This works in most cases - it will only fail if the exception
 639  
      * message contains a line that starts with:
 640  
      * <code>&quot;&nbsp;&nbsp;&nbsp;at&quot;.</code></p>
 641  
      * 
 642  
      * @param t is any throwable
 643  
      * @return List of stack frames
 644  
      */
 645  
     static List<String> getStackFrameList(final Throwable t) {
 646  12
         final String stackTrace = getStackTrace(t);
 647  12
         final String linebreak = SystemUtils.LINE_SEPARATOR;
 648  12
         final StringTokenizer frames = new StringTokenizer(stackTrace, linebreak);
 649  12
         final List<String> list = new ArrayList<String>();
 650  12
         boolean traceStarted = false;
 651  357
         while (frames.hasMoreTokens()) {
 652  351
             final String token = frames.nextToken();
 653  
             // Determine if the line starts with <whitespace>at
 654  351
             final int at = token.indexOf("at");
 655  351
             if (at != -1 && token.substring(0, at).trim().isEmpty()) {
 656  333
                 traceStarted = true;
 657  333
                 list.add(token);
 658  18
             } else if (traceStarted) {
 659  6
                 break;
 660  
             }
 661  345
         }
 662  12
         return list;
 663  
     }
 664  
 
 665  
     //-----------------------------------------------------------------------
 666  
     /**
 667  
      * Gets a short message summarising the exception.
 668  
      * <p>
 669  
      * The message returned is of the form
 670  
      * {ClassNameWithoutPackage}: {ThrowableMessage}
 671  
      *
 672  
      * @param th  the throwable to get a message for, null returns empty string
 673  
      * @return the message, non-null
 674  
      * @since Commons Lang 2.2
 675  
      */
 676  
     public static String getMessage(final Throwable th) {
 677  6
         if (th == null) {
 678  2
             return StringUtils.EMPTY;
 679  
         }
 680  4
         final String clsName = ClassUtils.getShortClassName(th, null);
 681  4
         final String msg = th.getMessage();
 682  4
         return clsName + ": " + StringUtils.defaultString(msg);
 683  
     }
 684  
 
 685  
     //-----------------------------------------------------------------------
 686  
     /**
 687  
      * Gets a short message summarising the root cause exception.
 688  
      * <p>
 689  
      * The message returned is of the form
 690  
      * {ClassNameWithoutPackage}: {ThrowableMessage}
 691  
      *
 692  
      * @param th  the throwable to get a message for, null returns empty string
 693  
      * @return the message, non-null
 694  
      * @since Commons Lang 2.2
 695  
      */
 696  
     public static String getRootCauseMessage(final Throwable th) {
 697  3
         Throwable root = ExceptionUtils.getRootCause(th);
 698  3
         root = root == null ? th : root;
 699  3
         return getMessage(root);
 700  
     }
 701  
 
 702  
     /**
 703  
      * Throw a checked exception without adding the exception to the throws
 704  
      * clause of the calling method. This method prevents throws clause
 705  
      * pollution and reduces the clutter of "Caused by" exceptions in the
 706  
      * stacktrace.
 707  
      * <p>
 708  
      * The use of this technique may be controversial, but exceedingly useful to
 709  
      * library developers.
 710  
      * <code>
 711  
      *  public int propagateExample { // note that there is no throws clause
 712  
      *      try {
 713  
      *          return invocation(); // throws IOException
 714  
      *      } catch (Exception e) {
 715  
      *          return ExceptionUtils.rethrow(e);  // propagates a checked exception
 716  
      *      }
 717  
      *  }
 718  
      * </code>
 719  
      * <p>
 720  
      * This is an alternative to the more conservative approach of wrapping the
 721  
      * checked exception in a RuntimeException:
 722  
      * <code>
 723  
      *  public int wrapExample { // note that there is no throws clause
 724  
      *      try {
 725  
      *          return invocation(); // throws IOException
 726  
      *      } catch (Error e) {
 727  
      *          throw e;
 728  
      *      } catch (RuntimeException e) {
 729  
      *          throw e;  // wraps a checked exception
 730  
      *      } catch (Exception e) {
 731  
      *          throw new UndeclaredThrowableException(e);  // wraps a checked exception
 732  
      *      }
 733  
      *  }
 734  
      * </code>
 735  
      * <p>
 736  
      * One downside to using this approach is that the java compiler will not
 737  
      * allow invoking code to specify a checked exception in a catch clause
 738  
      * unless there is some code path within the try block that has invoked a
 739  
      * method declared with that checked exception. If the invoking site wishes
 740  
      * to catch the shaded checked exception, it must either invoke the shaded
 741  
      * code through a method re-declaring the desired checked exception, or
 742  
      * catch Exception and use the instanceof operator. Either of these
 743  
      * techniques are required when interacting with non-java jvm code such as
 744  
      * Jyton, Scala, or Groovy, since these languages do not consider any
 745  
      * exceptions as checked.
 746  
      * 
 747  
      * @since 3.5
 748  
      * @see #wrapAndThrow(Throwable)
 749  
      *
 750  
      * @param throwable
 751  
      *            The throwable to rethrow.
 752  
      * @param <R> The type of the returned value.
 753  
      * @return Never actually returned, this generic type matches any type
 754  
      *         which the calling site requires. "Returning" the results of this
 755  
      *         method, as done in the propagateExample above, will satisfy the
 756  
      *         java compiler requirement that all code paths return a value.
 757  
      */
 758  
     public static <R> R rethrow(Throwable throwable) {
 759  
         // claim that the typeErasure invocation throws a RuntimeException
 760  3
         return ExceptionUtils.<R, RuntimeException> typeErasure(throwable);
 761  
     }
 762  
 
 763  
     /**
 764  
      * Claim a Throwable is another Exception type using type erasure. This
 765  
      * hides a checked exception from the java compiler, allowing a checked
 766  
      * exception to be thrown without having the exception in the method's throw
 767  
      * clause.
 768  
      */
 769  
     @SuppressWarnings("unchecked")
 770  
     private static <R, T extends Throwable> R typeErasure(Throwable throwable) throws T {
 771  3
         throw (T) throwable;
 772  
     }
 773  
 
 774  
     /**
 775  
      * Throw a checked exception without adding the exception to the throws
 776  
      * clause of the calling method. For checked exceptions, this method throws
 777  
      * an UndeclaredThrowableException wrapping the checked exception. For
 778  
      * Errors and RuntimeExceptions, the original exception is rethrown.
 779  
      * <p>
 780  
      * The downside to using this approach is that invoking code which needs to
 781  
      * handle specific checked exceptions must sniff up the exception chain to
 782  
      * determine if the caught exception was caused by the checked exception.
 783  
      * 
 784  
      * @since 3.5
 785  
      * @see #rethrow(Throwable)
 786  
      * @see #hasCause(Throwable, Class)
 787  
      * 
 788  
      * @param throwable
 789  
      *            The throwable to rethrow.
 790  
      * @param <R> The type of the returned value.
 791  
      * @return Never actually returned, this generic type matches any type
 792  
      *         which the calling site requires. "Returning" the results of this
 793  
      *         method will satisfy the java compiler requirement that all code
 794  
      *         paths return a value.
 795  
      */
 796  
     public static <R> R wrapAndThrow(Throwable throwable) {
 797  4
         if (throwable instanceof RuntimeException) {
 798  1
             throw (RuntimeException) throwable;
 799  
         }
 800  3
         if (throwable instanceof Error) {
 801  1
             throw (Error) throwable;
 802  
         }
 803  2
         throw new UndeclaredThrowableException(throwable);
 804  
     }
 805  
 
 806  
     /**
 807  
      * Does the throwable's causal chain have an immediate or wrapped exception
 808  
      * of the given type?
 809  
      * 
 810  
      * @since 3.5
 811  
      * @see #wrapAndThrow(Throwable)
 812  
      * 
 813  
      * @param chain
 814  
      *            The root of a Throwable causal chain.
 815  
      * @param type
 816  
      *            The exception type to test.
 817  
      * @return true, if chain is an instance of type or is an
 818  
      *         UndeclaredThrowableException wrapping a cause.
 819  
      */
 820  
     public static boolean hasCause(Throwable chain,
 821  
             Class<? extends Throwable> type) {
 822  4
         if (chain instanceof UndeclaredThrowableException) {
 823  2
             chain = chain.getCause();
 824  
         }
 825  4
         return type.isInstance(chain);
 826  
     }
 827  
 }