2 * Copyright (c) 1994, 2011, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
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).
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.
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
28 import org.apidesign.bck2brwsr.core.JavaScriptBody;
29 import org.apidesign.bck2brwsr.core.JavaScriptOnly;
32 * The {@code Throwable} class is the superclass of all errors and
33 * exceptions in the Java language. Only objects that are instances of this
34 * class (or one of its subclasses) are thrown by the Java Virtual Machine or
35 * can be thrown by the Java {@code throw} statement. Similarly, only
36 * this class or one of its subclasses can be the argument type in a
37 * {@code catch} clause.
39 * For the purposes of compile-time checking of exceptions, {@code
40 * Throwable} and any subclass of {@code Throwable} that is not also a
41 * subclass of either {@link RuntimeException} or {@link Error} are
42 * regarded as checked exceptions.
44 * <p>Instances of two subclasses, {@link java.lang.Error} and
45 * {@link java.lang.Exception}, are conventionally used to indicate
46 * that exceptional situations have occurred. Typically, these instances
47 * are freshly created in the context of the exceptional situation so
48 * as to include relevant information (such as stack trace data).
50 * <p>A throwable contains a snapshot of the execution stack of its
51 * thread at the time it was created. It can also contain a message
52 * string that gives more information about the error. Over time, a
53 * throwable can {@linkplain Throwable#addSuppressed suppress} other
54 * throwables from being propagated. Finally, the throwable can also
55 * contain a <i>cause</i>: another throwable that caused this
56 * throwable to be constructed. The recording of this causal information
57 * is referred to as the <i>chained exception</i> facility, as the
58 * cause can, itself, have a cause, and so on, leading to a "chain" of
59 * exceptions, each caused by another.
61 * <p>One reason that a throwable may have a cause is that the class that
62 * throws it is built atop a lower layered abstraction, and an operation on
63 * the upper layer fails due to a failure in the lower layer. It would be bad
64 * design to let the throwable thrown by the lower layer propagate outward, as
65 * it is generally unrelated to the abstraction provided by the upper layer.
66 * Further, doing so would tie the API of the upper layer to the details of
67 * its implementation, assuming the lower layer's exception was a checked
68 * exception. Throwing a "wrapped exception" (i.e., an exception containing a
69 * cause) allows the upper layer to communicate the details of the failure to
70 * its caller without incurring either of these shortcomings. It preserves
71 * the flexibility to change the implementation of the upper layer without
72 * changing its API (in particular, the set of exceptions thrown by its
75 * <p>A second reason that a throwable may have a cause is that the method
76 * that throws it must conform to a general-purpose interface that does not
77 * permit the method to throw the cause directly. For example, suppose
78 * a persistent collection conforms to the {@link java.util.Collection
79 * Collection} interface, and that its persistence is implemented atop
80 * {@code java.io}. Suppose the internals of the {@code add} method
81 * can throw an {@link java.io.IOException IOException}. The implementation
82 * can communicate the details of the {@code IOException} to its caller
83 * while conforming to the {@code Collection} interface by wrapping the
84 * {@code IOException} in an appropriate unchecked exception. (The
85 * specification for the persistent collection should indicate that it is
86 * capable of throwing such exceptions.)
88 * <p>A cause can be associated with a throwable in two ways: via a
89 * constructor that takes the cause as an argument, or via the
90 * {@link #initCause(Throwable)} method. New throwable classes that
91 * wish to allow causes to be associated with them should provide constructors
92 * that take a cause and delegate (perhaps indirectly) to one of the
93 * {@code Throwable} constructors that takes a cause.
95 * Because the {@code initCause} method is public, it allows a cause to be
96 * associated with any throwable, even a "legacy throwable" whose
97 * implementation predates the addition of the exception chaining mechanism to
100 * <p>By convention, class {@code Throwable} and its subclasses have two
101 * constructors, one that takes no arguments and one that takes a
102 * {@code String} argument that can be used to produce a detail message.
103 * Further, those subclasses that might likely have a cause associated with
104 * them should have two more constructors, one that takes a
105 * {@code Throwable} (the cause), and one that takes a
106 * {@code String} (the detail message) and a {@code Throwable} (the
110 * @author Josh Bloch (Added exception chaining and programmatic access to
111 * stack trace in 1.4.)
112 * @jls 11.2 Compile-Time Checking of Exceptions
115 public class Throwable implements Serializable {
116 /** use serialVersionUID from JDK 1.0.2 for interoperability */
117 private static final long serialVersionUID = -3042686055658047285L;
120 * Native code saves some indication of the stack backtrace in this slot.
122 private transient Object backtrace;
125 * Specific details about the Throwable. For example, for
126 * {@code FileNotFoundException}, this contains the name of
127 * the file that could not be found.
131 private String detailMessage;
135 * Holder class to defer initializing sentinel objects only used
138 private static class SentinelHolder {
140 * {@linkplain #setStackTrace(StackTraceElement[]) Setting the
141 * stack trace} to a one-element array containing this sentinel
142 * value indicates future attempts to set the stack trace will be
143 * ignored. The sentinal is equal to the result of calling:<br>
144 * {@code new StackTraceElement("", "", null, Integer.MIN_VALUE)}
146 public static final StackTraceElement STACK_TRACE_ELEMENT_SENTINEL =
147 new StackTraceElement("", "", null, Integer.MIN_VALUE);
150 * Sentinel value used in the serial form to indicate an immutable
153 public static final StackTraceElement[] STACK_TRACE_SENTINEL =
154 new StackTraceElement[] {STACK_TRACE_ELEMENT_SENTINEL};
158 * A shared value for an empty stack.
160 private static final StackTraceElement[] UNASSIGNED_STACK = new StackTraceElement[0];
163 * To allow Throwable objects to be made immutable and safely
164 * reused by the JVM, such as OutOfMemoryErrors, fields of
165 * Throwable that are writable in response to user actions, cause,
166 * stackTrace, and suppressedExceptions obey the following
169 * 1) The fields are initialized to a non-null sentinel value
170 * which indicates the value has logically not been set.
172 * 2) Writing a null to the field indicates further writes
175 * 3) The sentinel value may be replaced with another non-null
178 * For example, implementations of the HotSpot JVM have
179 * preallocated OutOfMemoryError objects to provide for better
180 * diagnosability of that situation. These objects are created
181 * without calling the constructor for that class and the fields
182 * in question are initialized to null. To support this
183 * capability, any new fields added to Throwable that require
184 * being initialized to a non-null value require a coordinated JVM
189 * The throwable that caused this throwable to get thrown, or null if this
190 * throwable was not caused by another throwable, or if the causative
191 * throwable is unknown. If this field is equal to this throwable itself,
192 * it indicates that the cause of this throwable has not yet been
198 private Throwable cause = this;
201 * The stack trace, as returned by {@link #getStackTrace()}.
203 * The field is initialized to a zero-length array. A {@code
204 * null} value of this field indicates subsequent calls to {@link
205 * #setStackTrace(StackTraceElement[])} and {@link
206 * #fillInStackTrace()} will be be no-ops.
211 private StackTraceElement[] stackTrace = UNASSIGNED_STACK;
213 // Setting this static field introduces an acceptable
214 // initialization dependency on a few java.util classes.
215 // I don't think this dependency is acceptable
216 // private static final List<Throwable> SUPPRESSED_SENTINEL =
217 // Collections.unmodifiableList(new ArrayList<Throwable>(0));
220 * The list of suppressed exceptions, as returned by {@link
221 * #getSuppressed()}. The list is initialized to a zero-element
222 * unmodifiable sentinel list. When a serialized Throwable is
223 * read in, if the {@code suppressedExceptions} field points to a
224 * zero-element list, the field is reset to the sentinel value.
229 // private List<Throwable> suppressedExceptions = SUPPRESSED_SENTINEL;
231 /** Message for trying to suppress a null exception. */
232 private static final String NULL_CAUSE_MESSAGE = "Cannot suppress a null exception.";
234 /** Message for trying to suppress oneself. */
235 private static final String SELF_SUPPRESSION_MESSAGE = "Self-suppression not permitted";
237 /** Caption for labeling causative exception stack traces */
238 @JavaScriptOnly(name="toString", value="function() { return this.toString__Ljava_lang_String_2().toString(); }")
239 private static void jsToString() {
242 @JavaScriptOnly(name="valueOf", value="function() { return this.toString().valueOf(); }")
243 private static void jsValudOf() {
245 private static final String CAUSE_CAPTION = "Caused by: ";
247 /** Caption for labeling suppressed exception stack traces */
248 private static final String SUPPRESSED_CAPTION = "Suppressed: ";
251 * Constructs a new throwable with {@code null} as its detail message.
252 * The cause is not initialized, and may subsequently be initialized by a
253 * call to {@link #initCause}.
255 * <p>The {@link #fillInStackTrace()} method is called to initialize
256 * the stack trace data in the newly created throwable.
263 * Constructs a new throwable with the specified detail message. The
264 * cause is not initialized, and may subsequently be initialized by
265 * a call to {@link #initCause}.
267 * <p>The {@link #fillInStackTrace()} method is called to initialize
268 * the stack trace data in the newly created throwable.
270 * @param message the detail message. The detail message is saved for
271 * later retrieval by the {@link #getMessage()} method.
273 public Throwable(String message) {
275 detailMessage = message;
279 * Constructs a new throwable with the specified detail message and
280 * cause. <p>Note that the detail message associated with
281 * {@code cause} is <i>not</i> automatically incorporated in
282 * this throwable's detail message.
284 * <p>The {@link #fillInStackTrace()} method is called to initialize
285 * the stack trace data in the newly created throwable.
287 * @param message the detail message (which is saved for later retrieval
288 * by the {@link #getMessage()} method).
289 * @param cause the cause (which is saved for later retrieval by the
290 * {@link #getCause()} method). (A {@code null} value is
291 * permitted, and indicates that the cause is nonexistent or
295 public Throwable(String message, Throwable cause) {
297 detailMessage = message;
302 * Constructs a new throwable with the specified cause and a detail
303 * message of {@code (cause==null ? null : cause.toString())} (which
304 * typically contains the class and detail message of {@code cause}).
305 * This constructor is useful for throwables that are little more than
306 * wrappers for other throwables (for example, {@link
307 * java.security.PrivilegedActionException}).
309 * <p>The {@link #fillInStackTrace()} method is called to initialize
310 * the stack trace data in the newly created throwable.
312 * @param cause the cause (which is saved for later retrieval by the
313 * {@link #getCause()} method). (A {@code null} value is
314 * permitted, and indicates that the cause is nonexistent or
318 public Throwable(Throwable cause) {
320 detailMessage = (cause==null ? null : cause.toString());
325 * Constructs a new throwable with the specified detail message,
326 * cause, {@linkplain #addSuppressed suppression} enabled or
327 * disabled, and writable stack trace enabled or disabled. If
328 * suppression is disabled, {@link #getSuppressed} for this object
329 * will return a zero-length array and calls to {@link
330 * #addSuppressed} that would otherwise append an exception to the
331 * suppressed list will have no effect. If the writable stack
332 * trace is false, this constructor will not call {@link
333 * #fillInStackTrace()}, a {@code null} will be written to the
334 * {@code stackTrace} field, and subsequent calls to {@code
335 * fillInStackTrace} and {@link
336 * #setStackTrace(StackTraceElement[])} will not set the stack
337 * trace. If the writable stack trace is false, {@link
338 * #getStackTrace} will return a zero length array.
340 * <p>Note that the other constructors of {@code Throwable} treat
341 * suppression as being enabled and the stack trace as being
342 * writable. Subclasses of {@code Throwable} should document any
343 * conditions under which suppression is disabled and document
344 * conditions under which the stack trace is not writable.
345 * Disabling of suppression should only occur in exceptional
346 * circumstances where special requirements exist, such as a
347 * virtual machine reusing exception objects under low-memory
348 * situations. Circumstances where a given exception object is
349 * repeatedly caught and rethrown, such as to implement control
350 * flow between two sub-systems, is another situation where
351 * immutable throwable objects would be appropriate.
353 * @param message the detail message.
354 * @param cause the cause. (A {@code null} value is permitted,
355 * and indicates that the cause is nonexistent or unknown.)
356 * @param enableSuppression whether or not suppression is enabled or disabled
357 * @param writableStackTrace whether or not the stack trace should be
360 * @see OutOfMemoryError
361 * @see NullPointerException
362 * @see ArithmeticException
365 protected Throwable(String message, Throwable cause,
366 boolean enableSuppression,
367 boolean writableStackTrace) {
368 if (writableStackTrace) {
373 detailMessage = message;
375 // if (!enableSuppression)
376 // suppressedExceptions = null;
380 * Returns the detail message string of this throwable.
382 * @return the detail message string of this {@code Throwable} instance
383 * (which may be {@code null}).
385 public String getMessage() {
386 return detailMessage;
390 * Creates a localized description of this throwable.
391 * Subclasses may override this method in order to produce a
392 * locale-specific message. For subclasses that do not override this
393 * method, the default implementation returns the same result as
394 * {@code getMessage()}.
396 * @return The localized description of this throwable.
399 public String getLocalizedMessage() {
404 * Returns the cause of this throwable or {@code null} if the
405 * cause is nonexistent or unknown. (The cause is the throwable that
406 * caused this throwable to get thrown.)
408 * <p>This implementation returns the cause that was supplied via one of
409 * the constructors requiring a {@code Throwable}, or that was set after
410 * creation with the {@link #initCause(Throwable)} method. While it is
411 * typically unnecessary to override this method, a subclass can override
412 * it to return a cause set by some other means. This is appropriate for
413 * a "legacy chained throwable" that predates the addition of chained
414 * exceptions to {@code Throwable}. Note that it is <i>not</i>
415 * necessary to override any of the {@code PrintStackTrace} methods,
416 * all of which invoke the {@code getCause} method to determine the
417 * cause of a throwable.
419 * @return the cause of this throwable or {@code null} if the
420 * cause is nonexistent or unknown.
423 public synchronized Throwable getCause() {
424 return (cause==this ? null : cause);
428 * Initializes the <i>cause</i> of this throwable to the specified value.
429 * (The cause is the throwable that caused this throwable to get thrown.)
431 * <p>This method can be called at most once. It is generally called from
432 * within the constructor, or immediately after creating the
433 * throwable. If this throwable was created
434 * with {@link #Throwable(Throwable)} or
435 * {@link #Throwable(String,Throwable)}, this method cannot be called
438 * <p>An example of using this method on a legacy throwable type
439 * without other support for setting the cause is:
444 * } catch (LowLevelException le) {
445 * throw (HighLevelException)
446 * new HighLevelException().initCause(le); // Legacy constructor
450 * @param cause the cause (which is saved for later retrieval by the
451 * {@link #getCause()} method). (A {@code null} value is
452 * permitted, and indicates that the cause is nonexistent or
454 * @return a reference to this {@code Throwable} instance.
455 * @throws IllegalArgumentException if {@code cause} is this
456 * throwable. (A throwable cannot be its own cause.)
457 * @throws IllegalStateException if this throwable was
458 * created with {@link #Throwable(Throwable)} or
459 * {@link #Throwable(String,Throwable)}, or this method has already
460 * been called on this throwable.
463 public synchronized Throwable initCause(Throwable cause) {
464 if (this.cause != this)
465 throw new IllegalStateException("Can't overwrite cause");
467 throw new IllegalArgumentException("Self-causation not permitted");
473 * Returns a short description of this throwable.
474 * The result is the concatenation of:
476 * <li> the {@linkplain Class#getName() name} of the class of this object
477 * <li> ": " (a colon and a space)
478 * <li> the result of invoking this object's {@link #getLocalizedMessage}
481 * If {@code getLocalizedMessage} returns {@code null}, then just
482 * the class name is returned.
484 * @return a string representation of this throwable.
486 public String toString() {
487 String s = getClass().getName();
488 String message = getLocalizedMessage();
489 return (message != null) ? (s + ": " + message) : s;
493 * Prints this throwable and its backtrace to the
494 * standard error stream. This method prints a stack trace for this
495 * {@code Throwable} object on the error output stream that is
496 * the value of the field {@code System.err}. The first line of
497 * output contains the result of the {@link #toString()} method for
498 * this object. Remaining lines represent data previously recorded by
499 * the method {@link #fillInStackTrace()}. The format of this
500 * information depends on the implementation, but the following
501 * example may be regarded as typical:
503 * java.lang.NullPointerException
504 * at MyClass.mash(MyClass.java:9)
505 * at MyClass.crunch(MyClass.java:6)
506 * at MyClass.main(MyClass.java:3)
507 * </pre></blockquote>
508 * This example was produced by running the program:
511 * public static void main(String[] args) {
514 * static void crunch(int[] a) {
517 * static void mash(int[] b) {
518 * System.out.println(b[0]);
522 * The backtrace for a throwable with an initialized, non-null cause
523 * should generally include the backtrace for the cause. The format
524 * of this information depends on the implementation, but the following
525 * example may be regarded as typical:
527 * HighLevelException: MidLevelException: LowLevelException
528 * at Junk.a(Junk.java:13)
529 * at Junk.main(Junk.java:4)
530 * Caused by: MidLevelException: LowLevelException
531 * at Junk.c(Junk.java:23)
532 * at Junk.b(Junk.java:17)
533 * at Junk.a(Junk.java:11)
535 * Caused by: LowLevelException
536 * at Junk.e(Junk.java:30)
537 * at Junk.d(Junk.java:27)
538 * at Junk.c(Junk.java:21)
541 * Note the presence of lines containing the characters {@code "..."}.
542 * These lines indicate that the remainder of the stack trace for this
543 * exception matches the indicated number of frames from the bottom of the
544 * stack trace of the exception that was caused by this exception (the
545 * "enclosing" exception). This shorthand can greatly reduce the length
546 * of the output in the common case where a wrapped exception is thrown
547 * from same method as the "causative exception" is caught. The above
548 * example was produced by running the program:
550 * public class Junk {
551 * public static void main(String args[]) {
554 * } catch(HighLevelException e) {
555 * e.printStackTrace();
558 * static void a() throws HighLevelException {
561 * } catch(MidLevelException e) {
562 * throw new HighLevelException(e);
565 * static void b() throws MidLevelException {
568 * static void c() throws MidLevelException {
571 * } catch(LowLevelException e) {
572 * throw new MidLevelException(e);
575 * static void d() throws LowLevelException {
578 * static void e() throws LowLevelException {
579 * throw new LowLevelException();
583 * class HighLevelException extends Exception {
584 * HighLevelException(Throwable cause) { super(cause); }
587 * class MidLevelException extends Exception {
588 * MidLevelException(Throwable cause) { super(cause); }
591 * class LowLevelException extends Exception {
594 * As of release 7, the platform supports the notion of
595 * <i>suppressed exceptions</i> (in conjunction with the {@code
596 * try}-with-resources statement). Any exceptions that were
597 * suppressed in order to deliver an exception are printed out
598 * beneath the stack trace. The format of this information
599 * depends on the implementation, but the following example may be
600 * regarded as typical:
603 * Exception in thread "main" java.lang.Exception: Something happened
604 * at Foo.bar(Foo.java:10)
605 * at Foo.main(Foo.java:5)
606 * Suppressed: Resource$CloseFailException: Resource ID = 0
607 * at Resource.close(Resource.java:26)
608 * at Foo.bar(Foo.java:9)
611 * Note that the "... n more" notation is used on suppressed exceptions
612 * just at it is used on causes. Unlike causes, suppressed exceptions are
613 * indented beyond their "containing exceptions."
615 * <p>An exception can have both a cause and one or more suppressed
618 * Exception in thread "main" java.lang.Exception: Main block
619 * at Foo3.main(Foo3.java:7)
620 * Suppressed: Resource$CloseFailException: Resource ID = 2
621 * at Resource.close(Resource.java:26)
622 * at Foo3.main(Foo3.java:5)
623 * Suppressed: Resource$CloseFailException: Resource ID = 1
624 * at Resource.close(Resource.java:26)
625 * at Foo3.main(Foo3.java:5)
626 * Caused by: java.lang.Exception: I did it
627 * at Foo3.main(Foo3.java:8)
629 * Likewise, a suppressed exception can have a cause:
631 * Exception in thread "main" java.lang.Exception: Main block
632 * at Foo4.main(Foo4.java:6)
633 * Suppressed: Resource2$CloseFailException: Resource ID = 1
634 * at Resource2.close(Resource2.java:20)
635 * at Foo4.main(Foo4.java:5)
636 * Caused by: java.lang.Exception: Rats, you caught me
637 * at Resource2$CloseFailException.<init>(Resource2.java:45)
641 public void printStackTrace() {
642 warn(getClass().getName() + ": " + getMessage());
644 @JavaScriptBody(args = { "msg" }, body = "if (console) console.warn(msg.toString());")
645 private native void warn(String msg);
648 * Prints this throwable and its backtrace to the specified print stream.
650 * @param s {@code PrintStream} to use for output
652 public void printStackTrace(PrintStream s) {
653 s.print(getClass().getName());
655 s.println(getMessage());
659 * Prints this throwable and its backtrace to the specified
662 * @param s {@code PrintWriter} to use for output
665 public void printStackTrace(PrintWriter s) {
666 s.append(getClass().getName()).append(": ").println(getMessage());
670 // * Wrapper class for PrintStream and PrintWriter to enable a single
671 // * implementation of printStackTrace.
673 // private abstract static class PrintStreamOrWriter {
674 // /** Returns the object to be locked when using this StreamOrWriter */
675 // abstract Object lock();
677 // /** Prints the specified string as a line on this StreamOrWriter */
678 // abstract void println(Object o);
681 // private static class WrappedPrintStream extends PrintStreamOrWriter {
682 // private final PrintStream printStream;
684 // WrappedPrintStream(PrintStream printStream) {
685 // this.printStream = printStream;
689 // return printStream;
692 // void println(Object o) {
693 // printStream.println(o);
697 // private static class WrappedPrintWriter extends PrintStreamOrWriter {
698 // private final PrintWriter printWriter;
700 // WrappedPrintWriter(PrintWriter printWriter) {
701 // this.printWriter = printWriter;
705 // return printWriter;
708 // void println(Object o) {
709 // printWriter.println(o);
714 * Fills in the execution stack trace. This method records within this
715 * {@code Throwable} object information about the current state of
716 * the stack frames for the current thread.
718 * <p>If the stack trace of this {@code Throwable} {@linkplain
719 * Throwable#Throwable(String, Throwable, boolean, boolean) is not
720 * writable}, calling this method has no effect.
722 * @return a reference to this {@code Throwable} instance.
723 * @see java.lang.Throwable#printStackTrace()
725 public synchronized Throwable fillInStackTrace() {
726 if (stackTrace != null ||
727 backtrace != null /* Out of protocol state */ ) {
729 stackTrace = UNASSIGNED_STACK;
734 @JavaScriptBody(args = { "dummy" }, body = "")
735 private native Throwable fillInStackTrace(int dummy);
738 * Provides programmatic access to the stack trace information printed by
739 * {@link #printStackTrace()}. Returns an array of stack trace elements,
740 * each representing one stack frame. The zeroth element of the array
741 * (assuming the array's length is non-zero) represents the top of the
742 * stack, which is the last method invocation in the sequence. Typically,
743 * this is the point at which this throwable was created and thrown.
744 * The last element of the array (assuming the array's length is non-zero)
745 * represents the bottom of the stack, which is the first method invocation
748 * <p>Some virtual machines may, under some circumstances, omit one
749 * or more stack frames from the stack trace. In the extreme case,
750 * a virtual machine that has no stack trace information concerning
751 * this throwable is permitted to return a zero-length array from this
752 * method. Generally speaking, the array returned by this method will
753 * contain one element for every frame that would be printed by
754 * {@code printStackTrace}. Writes to the returned array do not
755 * affect future calls to this method.
757 * @return an array of stack trace elements representing the stack trace
758 * pertaining to this throwable.
761 public StackTraceElement[] getStackTrace() {
762 return getOurStackTrace().clone();
765 private StackTraceElement[] getOurStackTrace() {
766 return new StackTraceElement[0];
770 * Sets the stack trace elements that will be returned by
771 * {@link #getStackTrace()} and printed by {@link #printStackTrace()}
772 * and related methods.
774 * This method, which is designed for use by RPC frameworks and other
775 * advanced systems, allows the client to override the default
776 * stack trace that is either generated by {@link #fillInStackTrace()}
777 * when a throwable is constructed or deserialized when a throwable is
778 * read from a serialization stream.
780 * <p>If the stack trace of this {@code Throwable} {@linkplain
781 * Throwable#Throwable(String, Throwable, boolean, boolean) is not
782 * writable}, calling this method has no effect other than
783 * validating its argument.
785 * @param stackTrace the stack trace elements to be associated with
786 * this {@code Throwable}. The specified array is copied by this
787 * call; changes in the specified array after the method invocation
788 * returns will have no affect on this {@code Throwable}'s stack
791 * @throws NullPointerException if {@code stackTrace} is
792 * {@code null} or if any of the elements of
793 * {@code stackTrace} are {@code null}
797 public void setStackTrace(StackTraceElement[] stackTrace) {
799 StackTraceElement[] defensiveCopy = stackTrace.clone();
800 for (int i = 0; i < defensiveCopy.length; i++) {
801 if (defensiveCopy[i] == null)
802 throw new NullPointerException("stackTrace[" + i + "]");
805 synchronized (this) {
806 if (this.stackTrace == null && // Immutable stack
807 backtrace == null) // Test for out of protocol state
809 this.stackTrace = defensiveCopy;
814 * Returns the number of elements in the stack trace (or 0 if the stack
815 * trace is unavailable).
817 * package-protection for use by SharedSecrets.
819 native int getStackTraceDepth();
822 * Returns the specified element of the stack trace.
824 * package-protection for use by SharedSecrets.
826 * @param index index of the element to return.
827 * @throws IndexOutOfBoundsException if {@code index < 0 ||
828 * index >= getStackTraceDepth() }
830 native StackTraceElement getStackTraceElement(int index);
833 * Reads a {@code Throwable} from a stream, enforcing
834 * well-formedness constraints on fields. Null entries and
835 * self-pointers are not allowed in the list of {@code
836 * suppressedExceptions}. Null entries are not allowed for stack
837 * trace elements. A null stack trace in the serial form results
838 * in a zero-length stack element array. A single-element stack
839 * trace whose entry is equal to {@code new StackTraceElement("",
840 * "", null, Integer.MIN_VALUE)} results in a {@code null} {@code
843 * Note that there are no constraints on the value the {@code
844 * cause} field can hold; both {@code null} and {@code this} are
845 * valid values for the field.
847 // private void readObject(ObjectInputStream s)
848 // throws IOException, ClassNotFoundException {
849 // s.defaultReadObject(); // read in all fields
850 // if (suppressedExceptions != null) {
851 // List<Throwable> suppressed = null;
852 // if (suppressedExceptions.isEmpty()) {
853 // // Use the sentinel for a zero-length list
854 // suppressed = SUPPRESSED_SENTINEL;
855 // } else { // Copy Throwables to new list
856 // suppressed = new ArrayList<Throwable>(1);
857 // for (Throwable t : suppressedExceptions) {
858 // // Enforce constraints on suppressed exceptions in
859 // // case of corrupt or malicious stream.
861 // throw new NullPointerException(NULL_CAUSE_MESSAGE);
863 // throw new IllegalArgumentException(SELF_SUPPRESSION_MESSAGE);
864 // suppressed.add(t);
867 // suppressedExceptions = suppressed;
868 // } // else a null suppressedExceptions field remains null
871 // * For zero-length stack traces, use a clone of
872 // * UNASSIGNED_STACK rather than UNASSIGNED_STACK itself to
873 // * allow identity comparison against UNASSIGNED_STACK in
874 // * getOurStackTrace. The identity of UNASSIGNED_STACK in
875 // * stackTrace indicates to the getOurStackTrace method that
876 // * the stackTrace needs to be constructed from the information
879 // if (stackTrace != null) {
880 // if (stackTrace.length == 0) {
881 // stackTrace = UNASSIGNED_STACK.clone();
882 // } else if (stackTrace.length == 1 &&
883 // // Check for the marker of an immutable stack trace
884 // SentinelHolder.STACK_TRACE_ELEMENT_SENTINEL.equals(stackTrace[0])) {
885 // stackTrace = null;
886 // } else { // Verify stack trace elements are non-null.
887 // for(StackTraceElement ste : stackTrace) {
889 // throw new NullPointerException("null StackTraceElement in serial stream. ");
893 // // A null stackTrace field in the serial form can result
894 // // from an exception serialized without that field in
895 // // older JDK releases; treat such exceptions as having
896 // // empty stack traces.
897 // stackTrace = UNASSIGNED_STACK.clone();
902 * Write a {@code Throwable} object to a stream.
904 * A {@code null} stack trace field is represented in the serial
905 * form as a one-element array whose element is equal to {@code
906 * new StackTraceElement("", "", null, Integer.MIN_VALUE)}.
908 // private synchronized void writeObject(ObjectOutputStream s)
909 // throws IOException {
910 // // Ensure that the stackTrace field is initialized to a
911 // // non-null value, if appropriate. As of JDK 7, a null stack
912 // // trace field is a valid value indicating the stack trace
913 // // should not be set.
914 // getOurStackTrace();
916 // StackTraceElement[] oldStackTrace = stackTrace;
918 // if (stackTrace == null)
919 // stackTrace = SentinelHolder.STACK_TRACE_SENTINEL;
920 // s.defaultWriteObject();
922 // stackTrace = oldStackTrace;
927 * Appends the specified exception to the exceptions that were
928 * suppressed in order to deliver this exception. This method is
929 * thread-safe and typically called (automatically and implicitly)
930 * by the {@code try}-with-resources statement.
932 * <p>The suppression behavior is enabled <em>unless</em> disabled
933 * {@linkplain #Throwable(String, Throwable, boolean, boolean) via
934 * a constructor}. When suppression is disabled, this method does
935 * nothing other than to validate its argument.
937 * <p>Note that when one exception {@linkplain
938 * #initCause(Throwable) causes} another exception, the first
939 * exception is usually caught and then the second exception is
940 * thrown in response. In other words, there is a causal
941 * connection between the two exceptions.
943 * In contrast, there are situations where two independent
944 * exceptions can be thrown in sibling code blocks, in particular
945 * in the {@code try} block of a {@code try}-with-resources
946 * statement and the compiler-generated {@code finally} block
947 * which closes the resource.
949 * In these situations, only one of the thrown exceptions can be
950 * propagated. In the {@code try}-with-resources statement, when
951 * there are two such exceptions, the exception originating from
952 * the {@code try} block is propagated and the exception from the
953 * {@code finally} block is added to the list of exceptions
954 * suppressed by the exception from the {@code try} block. As an
955 * exception unwinds the stack, it can accumulate multiple
956 * suppressed exceptions.
958 * <p>An exception may have suppressed exceptions while also being
959 * caused by another exception. Whether or not an exception has a
960 * cause is semantically known at the time of its creation, unlike
961 * whether or not an exception will suppress other exceptions
962 * which is typically only determined after an exception is
965 * <p>Note that programmer written code is also able to take
966 * advantage of calling this method in situations where there are
967 * multiple sibling exceptions and only one can be propagated.
969 * @param exception the exception to be added to the list of
970 * suppressed exceptions
971 * @throws IllegalArgumentException if {@code exception} is this
972 * throwable; a throwable cannot suppress itself.
973 * @throws NullPointerException if {@code exception} is {@code null}
976 public final synchronized void addSuppressed(Throwable exception) {
977 if (exception == this)
978 throw new IllegalArgumentException(SELF_SUPPRESSION_MESSAGE);
980 if (exception == null)
981 throw new NullPointerException(NULL_CAUSE_MESSAGE);
983 // if (suppressedExceptions == null) // Suppressed exceptions not recorded
986 // if (suppressedExceptions == SUPPRESSED_SENTINEL)
987 // suppressedExceptions = new ArrayList<Throwable>(1);
989 // suppressedExceptions.add(exception);
992 private static final Throwable[] EMPTY_THROWABLE_ARRAY = new Throwable[0];
995 * Returns an array containing all of the exceptions that were
996 * suppressed, typically by the {@code try}-with-resources
997 * statement, in order to deliver this exception.
999 * If no exceptions were suppressed or {@linkplain
1000 * #Throwable(String, Throwable, boolean, boolean) suppression is
1001 * disabled}, an empty array is returned. This method is
1002 * thread-safe. Writes to the returned array do not affect future
1003 * calls to this method.
1005 * @return an array containing all of the exceptions that were
1006 * suppressed to deliver this exception.
1009 public final synchronized Throwable[] getSuppressed() {
1010 return new Throwable[0];
1011 // if (suppressedExceptions == SUPPRESSED_SENTINEL ||
1012 // suppressedExceptions == null)
1013 // return EMPTY_THROWABLE_ARRAY;
1015 // return suppressedExceptions.toArray(EMPTY_THROWABLE_ARRAY);