1 /*
2 * Copyright 1994-2006 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Sun in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any questions.
24 */
25
26 package java.lang;
27 import java.io;
28
29 /**
30 * The <code>Throwable</code> class is the superclass of all errors and
31 * exceptions in the Java language. Only objects that are instances of this
32 * class (or one of its subclasses) are thrown by the Java Virtual Machine or
33 * can be thrown by the Java <code>throw</code> statement. Similarly, only
34 * this class or one of its subclasses can be the argument type in a
35 * <code>catch</code> clause.
36 *
37 * <p>Instances of two subclasses, {@link java.lang.Error} and
38 * {@link java.lang.Exception}, are conventionally used to indicate
39 * that exceptional situations have occurred. Typically, these instances
40 * are freshly created in the context of the exceptional situation so
41 * as to include relevant information (such as stack trace data).
42 *
43 * <p>A throwable contains a snapshot of the execution stack of its thread at
44 * the time it was created. It can also contain a message string that gives
45 * more information about the error. Finally, it can contain a <i>cause</i>:
46 * another throwable that caused this throwable to get thrown. The cause
47 * facility is new in release 1.4. It is also known as the <i>chained
48 * exception</i> facility, as the cause can, itself, have a cause, and so on,
49 * leading to a "chain" of exceptions, each caused by another.
50 *
51 * <p>One reason that a throwable may have a cause is that the class that
52 * throws it is built atop a lower layered abstraction, and an operation on
53 * the upper layer fails due to a failure in the lower layer. It would be bad
54 * design to let the throwable thrown by the lower layer propagate outward, as
55 * it is generally unrelated to the abstraction provided by the upper layer.
56 * Further, doing so would tie the API of the upper layer to the details of
57 * its implementation, assuming the lower layer's exception was a checked
58 * exception. Throwing a "wrapped exception" (i.e., an exception containing a
59 * cause) allows the upper layer to communicate the details of the failure to
60 * its caller without incurring either of these shortcomings. It preserves
61 * the flexibility to change the implementation of the upper layer without
62 * changing its API (in particular, the set of exceptions thrown by its
63 * methods).
64 *
65 * <p>A second reason that a throwable may have a cause is that the method
66 * that throws it must conform to a general-purpose interface that does not
67 * permit the method to throw the cause directly. For example, suppose
68 * a persistent collection conforms to the {@link java.util.Collection
69 * Collection} interface, and that its persistence is implemented atop
70 * <tt>java.io</tt>. Suppose the internals of the <tt>add</tt> method
71 * can throw an {@link java.io.IOException IOException}. The implementation
72 * can communicate the details of the <tt>IOException</tt> to its caller
73 * while conforming to the <tt>Collection</tt> interface by wrapping the
74 * <tt>IOException</tt> in an appropriate unchecked exception. (The
75 * specification for the persistent collection should indicate that it is
76 * capable of throwing such exceptions.)
77 *
78 * <p>A cause can be associated with a throwable in two ways: via a
79 * constructor that takes the cause as an argument, or via the
80 * {@link #initCause(Throwable)} method. New throwable classes that
81 * wish to allow causes to be associated with them should provide constructors
82 * that take a cause and delegate (perhaps indirectly) to one of the
83 * <tt>Throwable</tt> constructors that takes a cause. For example:
84 * <pre>
85 * try {
86 * lowLevelOp();
87 * } catch (LowLevelException le) {
88 * throw new HighLevelException(le); // Chaining-aware constructor
89 * }
90 * </pre>
91 * Because the <tt>initCause</tt> method is public, it allows a cause to be
92 * associated with any throwable, even a "legacy throwable" whose
93 * implementation predates the addition of the exception chaining mechanism to
94 * <tt>Throwable</tt>. For example:
95 * <pre>
96 * try {
97 * lowLevelOp();
98 * } catch (LowLevelException le) {
99 * throw (HighLevelException)
100 new HighLevelException().initCause(le); // Legacy constructor
101 * }
102 * </pre>
103 *
104 * <p>Prior to release 1.4, there were many throwables that had their own
105 * non-standard exception chaining mechanisms (
106 * {@link ExceptionInInitializerError}, {@link ClassNotFoundException},
107 * {@link java.lang.reflect.UndeclaredThrowableException},
108 * {@link java.lang.reflect.InvocationTargetException},
109 * {@link java.io.WriteAbortedException},
110 * {@link java.security.PrivilegedActionException},
111 * {@link java.awt.print.PrinterIOException},
112 * {@link java.rmi.RemoteException} and
113 * {@link javax.naming.NamingException}).
114 * All of these throwables have been retrofitted to
115 * use the standard exception chaining mechanism, while continuing to
116 * implement their "legacy" chaining mechanisms for compatibility.
117 *
118 * <p>Further, as of release 1.4, many general purpose <tt>Throwable</tt>
119 * classes (for example {@link Exception}, {@link RuntimeException},
120 * {@link Error}) have been retrofitted with constructors that take
121 * a cause. This was not strictly necessary, due to the existence of the
122 * <tt>initCause</tt> method, but it is more convenient and expressive to
123 * delegate to a constructor that takes a cause.
124 *
125 * <p>By convention, class <code>Throwable</code> and its subclasses have two
126 * constructors, one that takes no arguments and one that takes a
127 * <code>String</code> argument that can be used to produce a detail message.
128 * Further, those subclasses that might likely have a cause associated with
129 * them should have two more constructors, one that takes a
130 * <code>Throwable</code> (the cause), and one that takes a
131 * <code>String</code> (the detail message) and a <code>Throwable</code> (the
132 * cause).
133 *
134 * <p>Also introduced in release 1.4 is the {@link #getStackTrace()} method,
135 * which allows programmatic access to the stack trace information that was
136 * previously available only in text form, via the various forms of the
137 * {@link #printStackTrace()} method. This information has been added to the
138 * <i>serialized representation</i> of this class so <tt>getStackTrace</tt>
139 * and <tt>printStackTrace</tt> will operate properly on a throwable that
140 * was obtained by deserialization.
141 *
142 * @author unascribed
143 * @author Josh Bloch (Added exception chaining and programmatic access to
144 * stack trace in 1.4.)
145 * @since JDK1.0
146 */
147 public class Throwable implements Serializable {
148 /** use serialVersionUID from JDK 1.0.2 for interoperability */
149 private static final long serialVersionUID = -3042686055658047285L;
150
151 /**
152 * Native code saves some indication of the stack backtrace in this slot.
153 */
154 private transient Object backtrace;
155
156 /**
157 * Specific details about the Throwable. For example, for
158 * <tt>FileNotFoundException</tt>, this contains the name of
159 * the file that could not be found.
160 *
161 * @serial
162 */
163 private String detailMessage;
164
165 /**
166 * The throwable that caused this throwable to get thrown, or null if this
167 * throwable was not caused by another throwable, or if the causative
168 * throwable is unknown. If this field is equal to this throwable itself,
169 * it indicates that the cause of this throwable has not yet been
170 * initialized.
171 *
172 * @serial
173 * @since 1.4
174 */
175 private Throwable cause = this;
176
177 /**
178 * The stack trace, as returned by {@link #getStackTrace()}.
179 *
180 * @serial
181 * @since 1.4
182 */
183 private StackTraceElement[] stackTrace;
184 /*
185 * This field is lazily initialized on first use or serialization and
186 * nulled out when fillInStackTrace is called.
187 */
188
189 /**
190 * Constructs a new throwable with <code>null</code> as its detail message.
191 * The cause is not initialized, and may subsequently be initialized by a
192 * call to {@link #initCause}.
193 *
194 * <p>The {@link #fillInStackTrace()} method is called to initialize
195 * the stack trace data in the newly created throwable.
196 */
197 public Throwable() {
198 fillInStackTrace();
199 }
200
201 /**
202 * Constructs a new throwable with the specified detail message. The
203 * cause is not initialized, and may subsequently be initialized by
204 * a call to {@link #initCause}.
205 *
206 * <p>The {@link #fillInStackTrace()} method is called to initialize
207 * the stack trace data in the newly created throwable.
208 *
209 * @param message the detail message. The detail message is saved for
210 * later retrieval by the {@link #getMessage()} method.
211 */
212 public Throwable(String message) {
213 fillInStackTrace();
214 detailMessage = message;
215 }
216
217 /**
218 * Constructs a new throwable with the specified detail message and
219 * cause. <p>Note that the detail message associated with
220 * <code>cause</code> is <i>not</i> automatically incorporated in
221 * this throwable's detail message.
222 *
223 * <p>The {@link #fillInStackTrace()} method is called to initialize
224 * the stack trace data in the newly created throwable.
225 *
226 * @param message the detail message (which is saved for later retrieval
227 * by the {@link #getMessage()} method).
228 * @param cause the cause (which is saved for later retrieval by the
229 * {@link #getCause()} method). (A <tt>null</tt> value is
230 * permitted, and indicates that the cause is nonexistent or
231 * unknown.)
232 * @since 1.4
233 */
234 public Throwable(String message, Throwable cause) {
235 fillInStackTrace();
236 detailMessage = message;
237 this.cause = cause;
238 }
239
240 /**
241 * Constructs a new throwable with the specified cause and a detail
242 * message of <tt>(cause==null ? null : cause.toString())</tt> (which
243 * typically contains the class and detail message of <tt>cause</tt>).
244 * This constructor is useful for throwables that are little more than
245 * wrappers for other throwables (for example, {@link
246 * java.security.PrivilegedActionException}).
247 *
248 * <p>The {@link #fillInStackTrace()} method is called to initialize
249 * the stack trace data in the newly created throwable.
250 *
251 * @param cause the cause (which is saved for later retrieval by the
252 * {@link #getCause()} method). (A <tt>null</tt> value is
253 * permitted, and indicates that the cause is nonexistent or
254 * unknown.)
255 * @since 1.4
256 */
257 public Throwable(Throwable cause) {
258 fillInStackTrace();
259 detailMessage = (cause==null ? null : cause.toString());
260 this.cause = cause;
261 }
262
263 /**
264 * Returns the detail message string of this throwable.
265 *
266 * @return the detail message string of this <tt>Throwable</tt> instance
267 * (which may be <tt>null</tt>).
268 */
269 public String getMessage() {
270 return detailMessage;
271 }
272
273 /**
274 * Creates a localized description of this throwable.
275 * Subclasses may override this method in order to produce a
276 * locale-specific message. For subclasses that do not override this
277 * method, the default implementation returns the same result as
278 * <code>getMessage()</code>.
279 *
280 * @return The localized description of this throwable.
281 * @since JDK1.1
282 */
283 public String getLocalizedMessage() {
284 return getMessage();
285 }
286
287 /**
288 * Returns the cause of this throwable or <code>null</code> if the
289 * cause is nonexistent or unknown. (The cause is the throwable that
290 * caused this throwable to get thrown.)
291 *
292 * <p>This implementation returns the cause that was supplied via one of
293 * the constructors requiring a <tt>Throwable</tt>, or that was set after
294 * creation with the {@link #initCause(Throwable)} method. While it is
295 * typically unnecessary to override this method, a subclass can override
296 * it to return a cause set by some other means. This is appropriate for
297 * a "legacy chained throwable" that predates the addition of chained
298 * exceptions to <tt>Throwable</tt>. Note that it is <i>not</i>
299 * necessary to override any of the <tt>PrintStackTrace</tt> methods,
300 * all of which invoke the <tt>getCause</tt> method to determine the
301 * cause of a throwable.
302 *
303 * @return the cause of this throwable or <code>null</code> if the
304 * cause is nonexistent or unknown.
305 * @since 1.4
306 */
307 public Throwable getCause() {
308 return (cause==this ? null : cause);
309 }
310
311 /**
312 * Initializes the <i>cause</i> of this throwable to the specified value.
313 * (The cause is the throwable that caused this throwable to get thrown.)
314 *
315 * <p>This method can be called at most once. It is generally called from
316 * within the constructor, or immediately after creating the
317 * throwable. If this throwable was created
318 * with {@link #Throwable(Throwable)} or
319 * {@link #Throwable(String,Throwable)}, this method cannot be called
320 * even once.
321 *
322 * @param cause the cause (which is saved for later retrieval by the
323 * {@link #getCause()} method). (A <tt>null</tt> value is
324 * permitted, and indicates that the cause is nonexistent or
325 * unknown.)
326 * @return a reference to this <code>Throwable</code> instance.
327 * @throws IllegalArgumentException if <code>cause</code> is this
328 * throwable. (A throwable cannot be its own cause.)
329 * @throws IllegalStateException if this throwable was
330 * created with {@link #Throwable(Throwable)} or
331 * {@link #Throwable(String,Throwable)}, or this method has already
332 * been called on this throwable.
333 * @since 1.4
334 */
335 public synchronized Throwable initCause(Throwable cause) {
336 if (this.cause != this)
337 throw new IllegalStateException("Can't overwrite cause");
338 if (cause == this)
339 throw new IllegalArgumentException("Self-causation not permitted");
340 this.cause = cause;
341 return this;
342 }
343
344 /**
345 * Returns a short description of this throwable.
346 * The result is the concatenation of:
347 * <ul>
348 * <li> the {@linkplain Class#getName() name} of the class of this object
349 * <li> ": " (a colon and a space)
350 * <li> the result of invoking this object's {@link #getLocalizedMessage}
351 * method
352 * </ul>
353 * If <tt>getLocalizedMessage</tt> returns <tt>null</tt>, then just
354 * the class name is returned.
355 *
356 * @return a string representation of this throwable.
357 */
358 public String toString() {
359 String s = getClass().getName();
360 String message = getLocalizedMessage();
361 return (message != null) ? (s + ": " + message) : s;
362 }
363
364 /**
365 * Prints this throwable and its backtrace to the
366 * standard error stream. This method prints a stack trace for this
367 * <code>Throwable</code> object on the error output stream that is
368 * the value of the field <code>System.err</code>. The first line of
369 * output contains the result of the {@link #toString()} method for
370 * this object. Remaining lines represent data previously recorded by
371 * the method {@link #fillInStackTrace()}. The format of this
372 * information depends on the implementation, but the following
373 * example may be regarded as typical:
374 * <blockquote><pre>
375 * java.lang.NullPointerException
376 * at MyClass.mash(MyClass.java:9)
377 * at MyClass.crunch(MyClass.java:6)
378 * at MyClass.main(MyClass.java:3)
379 * </pre></blockquote>
380 * This example was produced by running the program:
381 * <pre>
382 * class MyClass {
383 * public static void main(String[] args) {
384 * crunch(null);
385 * }
386 * static void crunch(int[] a) {
387 * mash(a);
388 * }
389 * static void mash(int[] b) {
390 * System.out.println(b[0]);
391 * }
392 * }
393 * </pre>
394 * The backtrace for a throwable with an initialized, non-null cause
395 * should generally include the backtrace for the cause. The format
396 * of this information depends on the implementation, but the following
397 * example may be regarded as typical:
398 * <pre>
399 * HighLevelException: MidLevelException: LowLevelException
400 * at Junk.a(Junk.java:13)
401 * at Junk.main(Junk.java:4)
402 * Caused by: MidLevelException: LowLevelException
403 * at Junk.c(Junk.java:23)
404 * at Junk.b(Junk.java:17)
405 * at Junk.a(Junk.java:11)
406 * ... 1 more
407 * Caused by: LowLevelException
408 * at Junk.e(Junk.java:30)
409 * at Junk.d(Junk.java:27)
410 * at Junk.c(Junk.java:21)
411 * ... 3 more
412 * </pre>
413 * Note the presence of lines containing the characters <tt>"..."</tt>.
414 * These lines indicate that the remainder of the stack trace for this
415 * exception matches the indicated number of frames from the bottom of the
416 * stack trace of the exception that was caused by this exception (the
417 * "enclosing" exception). This shorthand can greatly reduce the length
418 * of the output in the common case where a wrapped exception is thrown
419 * from same method as the "causative exception" is caught. The above
420 * example was produced by running the program:
421 * <pre>
422 * public class Junk {
423 * public static void main(String args[]) {
424 * try {
425 * a();
426 * } catch(HighLevelException e) {
427 * e.printStackTrace();
428 * }
429 * }
430 * static void a() throws HighLevelException {
431 * try {
432 * b();
433 * } catch(MidLevelException e) {
434 * throw new HighLevelException(e);
435 * }
436 * }
437 * static void b() throws MidLevelException {
438 * c();
439 * }
440 * static void c() throws MidLevelException {
441 * try {
442 * d();
443 * } catch(LowLevelException e) {
444 * throw new MidLevelException(e);
445 * }
446 * }
447 * static void d() throws LowLevelException {
448 * e();
449 * }
450 * static void e() throws LowLevelException {
451 * throw new LowLevelException();
452 * }
453 * }
454 *
455 * class HighLevelException extends Exception {
456 * HighLevelException(Throwable cause) { super(cause); }
457 * }
458 *
459 * class MidLevelException extends Exception {
460 * MidLevelException(Throwable cause) { super(cause); }
461 * }
462 *
463 * class LowLevelException extends Exception {
464 * }
465 * </pre>
466 */
467 public void printStackTrace() {
468 printStackTrace(System.err);
469 }
470
471 /**
472 * Prints this throwable and its backtrace to the specified print stream.
473 *
474 * @param s <code>PrintStream</code> to use for output
475 */
476 public void printStackTrace(PrintStream s) {
477 synchronized (s) {
478 s.println(this);
479 StackTraceElement[] trace = getOurStackTrace();
480 for (int i=0; i < trace.length; i++)
481 s.println("\tat " + trace[i]);
482
483 Throwable ourCause = getCause();
484 if (ourCause != null)
485 ourCause.printStackTraceAsCause(s, trace);
486 }
487 }
488
489 /**
490 * Print our stack trace as a cause for the specified stack trace.
491 */
492 private void printStackTraceAsCause(PrintStream s,
493 StackTraceElement[] causedTrace)
494 {
495 // assert Thread.holdsLock(s);
496
497 // Compute number of frames in common between this and caused
498 StackTraceElement[] trace = getOurStackTrace();
499 int m = trace.length-1, n = causedTrace.length-1;
500 while (m >= 0 && n >=0 && trace[m].equals(causedTrace[n])) {
501 m--; n--;
502 }
503 int framesInCommon = trace.length - 1 - m;
504
505 s.println("Caused by: " + this);
506 for (int i=0; i <= m; i++)
507 s.println("\tat " + trace[i]);
508 if (framesInCommon != 0)
509 s.println("\t... " + framesInCommon + " more");
510
511 // Recurse if we have a cause
512 Throwable ourCause = getCause();
513 if (ourCause != null)
514 ourCause.printStackTraceAsCause(s, trace);
515 }
516
517 /**
518 * Prints this throwable and its backtrace to the specified
519 * print writer.
520 *
521 * @param s <code>PrintWriter</code> to use for output
522 * @since JDK1.1
523 */
524 public void printStackTrace(PrintWriter s) {
525 synchronized (s) {
526 s.println(this);
527 StackTraceElement[] trace = getOurStackTrace();
528 for (int i=0; i < trace.length; i++)
529 s.println("\tat " + trace[i]);
530
531 Throwable ourCause = getCause();
532 if (ourCause != null)
533 ourCause.printStackTraceAsCause(s, trace);
534 }
535 }
536
537 /**
538 * Print our stack trace as a cause for the specified stack trace.
539 */
540 private void printStackTraceAsCause(PrintWriter s,
541 StackTraceElement[] causedTrace)
542 {
543 // assert Thread.holdsLock(s);
544
545 // Compute number of frames in common between this and caused
546 StackTraceElement[] trace = getOurStackTrace();
547 int m = trace.length-1, n = causedTrace.length-1;
548 while (m >= 0 && n >=0 && trace[m].equals(causedTrace[n])) {
549 m--; n--;
550 }
551 int framesInCommon = trace.length - 1 - m;
552
553 s.println("Caused by: " + this);
554 for (int i=0; i <= m; i++)
555 s.println("\tat " + trace[i]);
556 if (framesInCommon != 0)
557 s.println("\t... " + framesInCommon + " more");
558
559 // Recurse if we have a cause
560 Throwable ourCause = getCause();
561 if (ourCause != null)
562 ourCause.printStackTraceAsCause(s, trace);
563 }
564
565 /**
566 * Fills in the execution stack trace. This method records within this
567 * <code>Throwable</code> object information about the current state of
568 * the stack frames for the current thread.
569 *
570 * @return a reference to this <code>Throwable</code> instance.
571 * @see java.lang.Throwable#printStackTrace()
572 */
573 public synchronized native Throwable fillInStackTrace();
574
575 /**
576 * Provides programmatic access to the stack trace information printed by
577 * {@link #printStackTrace()}. Returns an array of stack trace elements,
578 * each representing one stack frame. The zeroth element of the array
579 * (assuming the array's length is non-zero) represents the top of the
580 * stack, which is the last method invocation in the sequence. Typically,
581 * this is the point at which this throwable was created and thrown.
582 * The last element of the array (assuming the array's length is non-zero)
583 * represents the bottom of the stack, which is the first method invocation
584 * in the sequence.
585 *
586 * <p>Some virtual machines may, under some circumstances, omit one
587 * or more stack frames from the stack trace. In the extreme case,
588 * a virtual machine that has no stack trace information concerning
589 * this throwable is permitted to return a zero-length array from this
590 * method. Generally speaking, the array returned by this method will
591 * contain one element for every frame that would be printed by
592 * <tt>printStackTrace</tt>.
593 *
594 * @return an array of stack trace elements representing the stack trace
595 * pertaining to this throwable.
596 * @since 1.4
597 */
598 public StackTraceElement[] getStackTrace() {
599 return getOurStackTrace().clone();
600 }
601
602 private synchronized StackTraceElement[] getOurStackTrace() {
603 // Initialize stack trace if this is the first call to this method
604 if (stackTrace == null) {
605 int depth = getStackTraceDepth();
606 stackTrace = new StackTraceElement[depth];
607 for (int i=0; i < depth; i++)
608 stackTrace[i] = getStackTraceElement(i);
609 }
610 return stackTrace;
611 }
612
613 /**
614 * Sets the stack trace elements that will be returned by
615 * {@link #getStackTrace()} and printed by {@link #printStackTrace()}
616 * and related methods.
617 *
618 * This method, which is designed for use by RPC frameworks and other
619 * advanced systems, allows the client to override the default
620 * stack trace that is either generated by {@link #fillInStackTrace()}
621 * when a throwable is constructed or deserialized when a throwable is
622 * read from a serialization stream.
623 *
624 * @param stackTrace the stack trace elements to be associated with
625 * this <code>Throwable</code>. The specified array is copied by this
626 * call; changes in the specified array after the method invocation
627 * returns will have no affect on this <code>Throwable</code>'s stack
628 * trace.
629 *
630 * @throws NullPointerException if <code>stackTrace</code> is
631 * <code>null</code>, or if any of the elements of
632 * <code>stackTrace</code> are <code>null</code>
633 *
634 * @since 1.4
635 */
636 public void setStackTrace(StackTraceElement[] stackTrace) {
637 StackTraceElement[] defensiveCopy = stackTrace.clone();
638 for (int i = 0; i < defensiveCopy.length; i++)
639 if (defensiveCopy[i] == null)
640 throw new NullPointerException("stackTrace[" + i + "]");
641
642 this.stackTrace = defensiveCopy;
643 }
644
645 /**
646 * Returns the number of elements in the stack trace (or 0 if the stack
647 * trace is unavailable).
648 */
649 private native int getStackTraceDepth();
650
651 /**
652 * Returns the specified element of the stack trace.
653 *
654 * @param index index of the element to return.
655 * @throws IndexOutOfBoundsException if <tt>index < 0 ||
656 * index >= getStackTraceDepth() </tt>
657 */
658 private native StackTraceElement getStackTraceElement(int index);
659
660 private synchronized void writeObject(java.io.ObjectOutputStream s)
661 throws IOException
662 {
663 getOurStackTrace(); // Ensure that stackTrace field is initialized.
664 s.defaultWriteObject();
665 }
666 }
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