| /* |
| * Copyright (C) 2014 The Android Open Source Project |
| * Copyright (c) 1994, 2013, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package java.lang; |
| import dalvik.annotation.optimization.FastNative; |
| import java.io.*; |
| import java.util.*; |
| |
| /** |
| * The {@code Throwable} class is the superclass of all errors and |
| * exceptions in the Java language. Only objects that are instances of this |
| * class (or one of its subclasses) are thrown by the Java Virtual Machine or |
| * can be thrown by the Java {@code throw} statement. Similarly, only |
| * this class or one of its subclasses can be the argument type in a |
| * {@code catch} clause. |
| * |
| * For the purposes of compile-time checking of exceptions, {@code |
| * Throwable} and any subclass of {@code Throwable} that is not also a |
| * subclass of either {@link RuntimeException} or {@link Error} are |
| * regarded as checked exceptions. |
| * |
| * <p>Instances of two subclasses, {@link java.lang.Error} and |
| * {@link java.lang.Exception}, are conventionally used to indicate |
| * that exceptional situations have occurred. Typically, these instances |
| * are freshly created in the context of the exceptional situation so |
| * as to include relevant information (such as stack trace data). |
| * |
| * <p>A throwable contains a snapshot of the execution stack of its |
| * thread at the time it was created. It can also contain a message |
| * string that gives more information about the error. Over time, a |
| * throwable can {@linkplain Throwable#addSuppressed suppress} other |
| * throwables from being propagated. Finally, the throwable can also |
| * contain a <i>cause</i>: another throwable that caused this |
| * throwable to be constructed. The recording of this causal information |
| * is referred to as the <i>chained exception</i> facility, as the |
| * cause can, itself, have a cause, and so on, leading to a "chain" of |
| * exceptions, each caused by another. |
| * |
| * <p>One reason that a throwable may have a cause is that the class that |
| * throws it is built atop a lower layered abstraction, and an operation on |
| * the upper layer fails due to a failure in the lower layer. It would be bad |
| * design to let the throwable thrown by the lower layer propagate outward, as |
| * it is generally unrelated to the abstraction provided by the upper layer. |
| * Further, doing so would tie the API of the upper layer to the details of |
| * its implementation, assuming the lower layer's exception was a checked |
| * exception. Throwing a "wrapped exception" (i.e., an exception containing a |
| * cause) allows the upper layer to communicate the details of the failure to |
| * its caller without incurring either of these shortcomings. It preserves |
| * the flexibility to change the implementation of the upper layer without |
| * changing its API (in particular, the set of exceptions thrown by its |
| * methods). |
| * |
| * <p>A second reason that a throwable may have a cause is that the method |
| * that throws it must conform to a general-purpose interface that does not |
| * permit the method to throw the cause directly. For example, suppose |
| * a persistent collection conforms to the {@link java.util.Collection |
| * Collection} interface, and that its persistence is implemented atop |
| * {@code java.io}. Suppose the internals of the {@code add} method |
| * can throw an {@link java.io.IOException IOException}. The implementation |
| * can communicate the details of the {@code IOException} to its caller |
| * while conforming to the {@code Collection} interface by wrapping the |
| * {@code IOException} in an appropriate unchecked exception. (The |
| * specification for the persistent collection should indicate that it is |
| * capable of throwing such exceptions.) |
| * |
| * <p>A cause can be associated with a throwable in two ways: via a |
| * constructor that takes the cause as an argument, or via the |
| * {@link #initCause(Throwable)} method. New throwable classes that |
| * wish to allow causes to be associated with them should provide constructors |
| * that take a cause and delegate (perhaps indirectly) to one of the |
| * {@code Throwable} constructors that takes a cause. |
| * |
| * Because the {@code initCause} method is public, it allows a cause to be |
| * associated with any throwable, even a "legacy throwable" whose |
| * implementation predates the addition of the exception chaining mechanism to |
| * {@code Throwable}. |
| * |
| * <p>By convention, class {@code Throwable} and its subclasses have two |
| * constructors, one that takes no arguments and one that takes a |
| * {@code String} argument that can be used to produce a detail message. |
| * Further, those subclasses that might likely have a cause associated with |
| * them should have two more constructors, one that takes a |
| * {@code Throwable} (the cause), and one that takes a |
| * {@code String} (the detail message) and a {@code Throwable} (the |
| * cause). |
| * |
| * @author unascribed |
| * @author Josh Bloch (Added exception chaining and programmatic access to |
| * stack trace in 1.4.) |
| * @jls 11.2 Compile-Time Checking of Exceptions |
| * @since JDK1.0 |
| */ |
| public class Throwable implements Serializable { |
| /** use serialVersionUID from JDK 1.0.2 for interoperability */ |
| private static final long serialVersionUID = -3042686055658047285L; |
| |
| /** |
| * Native code saves some indication of the stack backtrace in this slot. |
| */ |
| private transient Object backtrace; |
| |
| /** |
| * Specific details about the Throwable. For example, for |
| * {@code FileNotFoundException}, this contains the name of |
| * the file that could not be found. |
| * |
| * @serial |
| */ |
| private String detailMessage; |
| |
| |
| /** |
| * Holder class to defer initializing sentinel objects only used |
| * for serialization. |
| */ |
| private static class SentinelHolder { |
| /** |
| * {@linkplain #setStackTrace(StackTraceElement[]) Setting the |
| * stack trace} to a one-element array containing this sentinel |
| * value indicates future attempts to set the stack trace will be |
| * ignored. The sentinal is equal to the result of calling:<br> |
| * {@code new StackTraceElement("", "", null, Integer.MIN_VALUE)} |
| */ |
| public static final StackTraceElement STACK_TRACE_ELEMENT_SENTINEL = |
| new StackTraceElement("", "", null, Integer.MIN_VALUE); |
| |
| /** |
| * Sentinel value used in the serial form to indicate an immutable |
| * stack trace. |
| */ |
| public static final StackTraceElement[] STACK_TRACE_SENTINEL = |
| new StackTraceElement[] {STACK_TRACE_ELEMENT_SENTINEL}; |
| } |
| |
| // Android-removed: Use libcore.util.EmptyArray for the empty stack trace |
| // Adding the constant UNASSIGNED_STACK breaks serialization of some subclasses |
| // /** |
| // * A shared value for an empty stack. |
| // */ |
| // private static final StackTraceElement[] UNASSIGNED_STACK = new StackTraceElement[0]; |
| |
| /* |
| * To allow Throwable objects to be made immutable and safely |
| * reused by the JVM, such as OutOfMemoryErrors, fields of |
| * Throwable that are writable in response to user actions, cause, |
| * stackTrace, and suppressedExceptions obey the following |
| * protocol: |
| * |
| * 1) The fields are initialized to a non-null sentinel value |
| * which indicates the value has logically not been set. |
| * |
| * 2) Writing a null to the field indicates further writes |
| * are forbidden |
| * |
| * 3) The sentinel value may be replaced with another non-null |
| * value. |
| * |
| * For example, implementations of the HotSpot JVM have |
| * preallocated OutOfMemoryError objects to provide for better |
| * diagnosability of that situation. These objects are created |
| * without calling the constructor for that class and the fields |
| * in question are initialized to null. To support this |
| * capability, any new fields added to Throwable that require |
| * being initialized to a non-null value require a coordinated JVM |
| * change. |
| */ |
| |
| /** |
| * The throwable that caused this throwable to get thrown, or null if this |
| * throwable was not caused by another throwable, or if the causative |
| * throwable is unknown. If this field is equal to this throwable itself, |
| * it indicates that the cause of this throwable has not yet been |
| * initialized. |
| * |
| * @serial |
| * @since 1.4 |
| */ |
| private Throwable cause = this; |
| |
| /** |
| * The stack trace, as returned by {@link #getStackTrace()}. |
| * |
| * The field is initialized to a zero-length array. A {@code |
| * null} value of this field indicates subsequent calls to {@link |
| * #setStackTrace(StackTraceElement[])} and {@link |
| * #fillInStackTrace()} will be be no-ops. |
| * |
| * @serial |
| * @since 1.4 |
| */ |
| // Android-changed: Use libcore.util.EmptyArray for the empty stack trace |
| // private StackTraceElement[] stackTrace = UNASSIGNED_STACK; |
| private StackTraceElement[] stackTrace = libcore.util.EmptyArray.STACK_TRACE_ELEMENT; |
| |
| // Android-removed: Use empty collection in place of SUPPRESSED_SENTINEL |
| // Adding this constant breaks serialization of some subclasses |
| /* |
| // Setting this static field introduces an acceptable |
| // initialization dependency on a few java.util classes. |
| private static final List<Throwable> SUPPRESSED_SENTINEL = |
| Collections.unmodifiableList(new ArrayList<Throwable>(0)); |
| */ |
| |
| /** |
| * The list of suppressed exceptions, as returned by {@link |
| * #getSuppressed()}. The list is initialized to a zero-element |
| * unmodifiable sentinel list. When a serialized Throwable is |
| * read in, if the {@code suppressedExceptions} field points to a |
| * zero-element list, the field is reset to the sentinel value. |
| * |
| * @serial |
| * @since 1.7 |
| */ |
| // Android-changed: Use empty collection in place of SUPPRESSED_SENTINEL |
| // private List<Throwable> suppressedExceptions = SUPPRESSED_SENTINEL; |
| private List<Throwable> suppressedExceptions = Collections.emptyList(); |
| |
| /** Message for trying to suppress a null exception. */ |
| private static final String NULL_CAUSE_MESSAGE = "Cannot suppress a null exception."; |
| |
| /** Message for trying to suppress oneself. */ |
| private static final String SELF_SUPPRESSION_MESSAGE = "Self-suppression not permitted"; |
| |
| /** Caption for labeling causative exception stack traces */ |
| private static final String CAUSE_CAPTION = "Caused by: "; |
| |
| /** Caption for labeling suppressed exception stack traces */ |
| private static final String SUPPRESSED_CAPTION = "Suppressed: "; |
| |
| /** |
| * Constructs a new throwable with {@code null} as its detail message. |
| * The cause is not initialized, and may subsequently be initialized by a |
| * call to {@link #initCause}. |
| * |
| * <p>The {@link #fillInStackTrace()} method is called to initialize |
| * the stack trace data in the newly created throwable. |
| */ |
| public Throwable() { |
| fillInStackTrace(); |
| } |
| |
| /** |
| * Constructs a new throwable with the specified detail message. The |
| * cause is not initialized, and may subsequently be initialized by |
| * a call to {@link #initCause}. |
| * |
| * <p>The {@link #fillInStackTrace()} method is called to initialize |
| * the stack trace data in the newly created throwable. |
| * |
| * @param message the detail message. The detail message is saved for |
| * later retrieval by the {@link #getMessage()} method. |
| */ |
| public Throwable(String message) { |
| fillInStackTrace(); |
| detailMessage = message; |
| } |
| |
| /** |
| * Constructs a new throwable with the specified detail message and |
| * cause. <p>Note that the detail message associated with |
| * {@code cause} is <i>not</i> automatically incorporated in |
| * this throwable's detail message. |
| * |
| * <p>The {@link #fillInStackTrace()} method is called to initialize |
| * the stack trace data in the newly created throwable. |
| * |
| * @param message the detail message (which is saved for later retrieval |
| * by the {@link #getMessage()} method). |
| * @param cause the cause (which is saved for later retrieval by the |
| * {@link #getCause()} method). (A {@code null} value is |
| * permitted, and indicates that the cause is nonexistent or |
| * unknown.) |
| * @since 1.4 |
| */ |
| public Throwable(String message, Throwable cause) { |
| fillInStackTrace(); |
| detailMessage = message; |
| this.cause = cause; |
| } |
| |
| /** |
| * Constructs a new throwable with the specified cause and a detail |
| * message of {@code (cause==null ? null : cause.toString())} (which |
| * typically contains the class and detail message of {@code cause}). |
| * This constructor is useful for throwables that are little more than |
| * wrappers for other throwables (for example, {@link |
| * java.security.PrivilegedActionException}). |
| * |
| * <p>The {@link #fillInStackTrace()} method is called to initialize |
| * the stack trace data in the newly created throwable. |
| * |
| * @param cause the cause (which is saved for later retrieval by the |
| * {@link #getCause()} method). (A {@code null} value is |
| * permitted, and indicates that the cause is nonexistent or |
| * unknown.) |
| * @since 1.4 |
| */ |
| public Throwable(Throwable cause) { |
| fillInStackTrace(); |
| detailMessage = (cause==null ? null : cause.toString()); |
| this.cause = cause; |
| } |
| |
| /** |
| * Constructs a new throwable with the specified detail message, |
| * cause, {@linkplain #addSuppressed suppression} enabled or |
| * disabled, and writable stack trace enabled or disabled. If |
| * suppression is disabled, {@link #getSuppressed} for this object |
| * will return a zero-length array and calls to {@link |
| * #addSuppressed} that would otherwise append an exception to the |
| * suppressed list will have no effect. If the writable stack |
| * trace is false, this constructor will not call {@link |
| * #fillInStackTrace()}, a {@code null} will be written to the |
| * {@code stackTrace} field, and subsequent calls to {@code |
| * fillInStackTrace} and {@link |
| * #setStackTrace(StackTraceElement[])} will not set the stack |
| * trace. If the writable stack trace is false, {@link |
| * #getStackTrace} will return a zero length array. |
| * |
| * <p>Note that the other constructors of {@code Throwable} treat |
| * suppression as being enabled and the stack trace as being |
| * writable. Subclasses of {@code Throwable} should document any |
| * conditions under which suppression is disabled and document |
| * conditions under which the stack trace is not writable. |
| * Disabling of suppression should only occur in exceptional |
| * circumstances where special requirements exist, such as a |
| * virtual machine reusing exception objects under low-memory |
| * situations. Circumstances where a given exception object is |
| * repeatedly caught and rethrown, such as to implement control |
| * flow between two sub-systems, is another situation where |
| * immutable throwable objects would be appropriate. |
| * |
| * @param message the detail message. |
| * @param cause the cause. (A {@code null} value is permitted, |
| * and indicates that the cause is nonexistent or unknown.) |
| * @param enableSuppression whether or not suppression is enabled or disabled |
| * @param writableStackTrace whether or not the stack trace should be |
| * writable |
| * |
| * @see OutOfMemoryError |
| * @see NullPointerException |
| * @see ArithmeticException |
| * @since 1.7 |
| */ |
| protected Throwable(String message, Throwable cause, |
| boolean enableSuppression, |
| boolean writableStackTrace) { |
| if (writableStackTrace) { |
| fillInStackTrace(); |
| } else { |
| stackTrace = null; |
| } |
| detailMessage = message; |
| this.cause = cause; |
| if (!enableSuppression) |
| suppressedExceptions = null; |
| } |
| |
| /** |
| * Returns the detail message string of this throwable. |
| * |
| * @return the detail message string of this {@code Throwable} instance |
| * (which may be {@code null}). |
| */ |
| public String getMessage() { |
| return detailMessage; |
| } |
| |
| /** |
| * Creates a localized description of this throwable. |
| * Subclasses may override this method in order to produce a |
| * locale-specific message. For subclasses that do not override this |
| * method, the default implementation returns the same result as |
| * {@code getMessage()}. |
| * |
| * @return The localized description of this throwable. |
| * @since JDK1.1 |
| */ |
| public String getLocalizedMessage() { |
| return getMessage(); |
| } |
| |
| /** |
| * Returns the cause of this throwable or {@code null} if the |
| * cause is nonexistent or unknown. (The cause is the throwable that |
| * caused this throwable to get thrown.) |
| * |
| * <p>This implementation returns the cause that was supplied via one of |
| * the constructors requiring a {@code Throwable}, or that was set after |
| * creation with the {@link #initCause(Throwable)} method. While it is |
| * typically unnecessary to override this method, a subclass can override |
| * it to return a cause set by some other means. This is appropriate for |
| * a "legacy chained throwable" that predates the addition of chained |
| * exceptions to {@code Throwable}. Note that it is <i>not</i> |
| * necessary to override any of the {@code PrintStackTrace} methods, |
| * all of which invoke the {@code getCause} method to determine the |
| * cause of a throwable. |
| * |
| * @return the cause of this throwable or {@code null} if the |
| * cause is nonexistent or unknown. |
| * @since 1.4 |
| */ |
| public synchronized Throwable getCause() { |
| return (cause==this ? null : cause); |
| } |
| |
| /** |
| * Initializes the <i>cause</i> of this throwable to the specified value. |
| * (The cause is the throwable that caused this throwable to get thrown.) |
| * |
| * <p>This method can be called at most once. It is generally called from |
| * within the constructor, or immediately after creating the |
| * throwable. If this throwable was created |
| * with {@link #Throwable(Throwable)} or |
| * {@link #Throwable(String,Throwable)}, this method cannot be called |
| * even once. |
| * |
| * <p>An example of using this method on a legacy throwable type |
| * without other support for setting the cause is: |
| * |
| * <pre> |
| * try { |
| * lowLevelOp(); |
| * } catch (LowLevelException le) { |
| * throw (HighLevelException) |
| * new HighLevelException().initCause(le); // Legacy constructor |
| * } |
| * </pre> |
| * |
| * @param cause the cause (which is saved for later retrieval by the |
| * {@link #getCause()} method). (A {@code null} value is |
| * permitted, and indicates that the cause is nonexistent or |
| * unknown.) |
| * @return a reference to this {@code Throwable} instance. |
| * @throws IllegalArgumentException if {@code cause} is this |
| * throwable. (A throwable cannot be its own cause.) |
| * @throws IllegalStateException if this throwable was |
| * created with {@link #Throwable(Throwable)} or |
| * {@link #Throwable(String,Throwable)}, or this method has already |
| * been called on this throwable. |
| * @since 1.4 |
| */ |
| public synchronized Throwable initCause(Throwable cause) { |
| if (this.cause != this) |
| throw new IllegalStateException("Can't overwrite cause with " + |
| Objects.toString(cause, "a null"), this); |
| if (cause == this) |
| throw new IllegalArgumentException("Self-causation not permitted", this); |
| this.cause = cause; |
| return this; |
| } |
| |
| /** |
| * Returns a short description of this throwable. |
| * The result is the concatenation of: |
| * <ul> |
| * <li> the {@linkplain Class#getName() name} of the class of this object |
| * <li> ": " (a colon and a space) |
| * <li> the result of invoking this object's {@link #getLocalizedMessage} |
| * method |
| * </ul> |
| * If {@code getLocalizedMessage} returns {@code null}, then just |
| * the class name is returned. |
| * |
| * @return a string representation of this throwable. |
| */ |
| public String toString() { |
| String s = getClass().getName(); |
| String message = getLocalizedMessage(); |
| return (message != null) ? (s + ": " + message) : s; |
| } |
| |
| /** |
| * Prints this throwable and its backtrace to the |
| * standard error stream. This method prints a stack trace for this |
| * {@code Throwable} object on the error output stream that is |
| * the value of the field {@code System.err}. The first line of |
| * output contains the result of the {@link #toString()} method for |
| * this object. Remaining lines represent data previously recorded by |
| * the method {@link #fillInStackTrace()}. The format of this |
| * information depends on the implementation, but the following |
| * example may be regarded as typical: |
| * <blockquote><pre> |
| * java.lang.NullPointerException |
| * at MyClass.mash(MyClass.java:9) |
| * at MyClass.crunch(MyClass.java:6) |
| * at MyClass.main(MyClass.java:3) |
| * </pre></blockquote> |
| * This example was produced by running the program: |
| * <pre> |
| * class MyClass { |
| * public static void main(String[] args) { |
| * crunch(null); |
| * } |
| * static void crunch(int[] a) { |
| * mash(a); |
| * } |
| * static void mash(int[] b) { |
| * System.out.println(b[0]); |
| * } |
| * } |
| * </pre> |
| * The backtrace for a throwable with an initialized, non-null cause |
| * should generally include the backtrace for the cause. The format |
| * of this information depends on the implementation, but the following |
| * example may be regarded as typical: |
| * <pre> |
| * HighLevelException: MidLevelException: LowLevelException |
| * at Junk.a(Junk.java:13) |
| * at Junk.main(Junk.java:4) |
| * Caused by: MidLevelException: LowLevelException |
| * at Junk.c(Junk.java:23) |
| * at Junk.b(Junk.java:17) |
| * at Junk.a(Junk.java:11) |
| * ... 1 more |
| * Caused by: LowLevelException |
| * at Junk.e(Junk.java:30) |
| * at Junk.d(Junk.java:27) |
| * at Junk.c(Junk.java:21) |
| * ... 3 more |
| * </pre> |
| * Note the presence of lines containing the characters {@code "..."}. |
| * These lines indicate that the remainder of the stack trace for this |
| * exception matches the indicated number of frames from the bottom of the |
| * stack trace of the exception that was caused by this exception (the |
| * "enclosing" exception). This shorthand can greatly reduce the length |
| * of the output in the common case where a wrapped exception is thrown |
| * from same method as the "causative exception" is caught. The above |
| * example was produced by running the program: |
| * <pre> |
| * public class Junk { |
| * public static void main(String args[]) { |
| * try { |
| * a(); |
| * } catch(HighLevelException e) { |
| * e.printStackTrace(); |
| * } |
| * } |
| * static void a() throws HighLevelException { |
| * try { |
| * b(); |
| * } catch(MidLevelException e) { |
| * throw new HighLevelException(e); |
| * } |
| * } |
| * static void b() throws MidLevelException { |
| * c(); |
| * } |
| * static void c() throws MidLevelException { |
| * try { |
| * d(); |
| * } catch(LowLevelException e) { |
| * throw new MidLevelException(e); |
| * } |
| * } |
| * static void d() throws LowLevelException { |
| * e(); |
| * } |
| * static void e() throws LowLevelException { |
| * throw new LowLevelException(); |
| * } |
| * } |
| * |
| * class HighLevelException extends Exception { |
| * HighLevelException(Throwable cause) { super(cause); } |
| * } |
| * |
| * class MidLevelException extends Exception { |
| * MidLevelException(Throwable cause) { super(cause); } |
| * } |
| * |
| * class LowLevelException extends Exception { |
| * } |
| * </pre> |
| * As of release 7, the platform supports the notion of |
| * <i>suppressed exceptions</i> (in conjunction with the {@code |
| * try}-with-resources statement). Any exceptions that were |
| * suppressed in order to deliver an exception are printed out |
| * beneath the stack trace. The format of this information |
| * depends on the implementation, but the following example may be |
| * regarded as typical: |
| * |
| * <pre> |
| * Exception in thread "main" java.lang.Exception: Something happened |
| * at Foo.bar(Foo.java:10) |
| * at Foo.main(Foo.java:5) |
| * Suppressed: Resource$CloseFailException: Resource ID = 0 |
| * at Resource.close(Resource.java:26) |
| * at Foo.bar(Foo.java:9) |
| * ... 1 more |
| * </pre> |
| * Note that the "... n more" notation is used on suppressed exceptions |
| * just at it is used on causes. Unlike causes, suppressed exceptions are |
| * indented beyond their "containing exceptions." |
| * |
| * <p>An exception can have both a cause and one or more suppressed |
| * exceptions: |
| * <pre> |
| * Exception in thread "main" java.lang.Exception: Main block |
| * at Foo3.main(Foo3.java:7) |
| * Suppressed: Resource$CloseFailException: Resource ID = 2 |
| * at Resource.close(Resource.java:26) |
| * at Foo3.main(Foo3.java:5) |
| * Suppressed: Resource$CloseFailException: Resource ID = 1 |
| * at Resource.close(Resource.java:26) |
| * at Foo3.main(Foo3.java:5) |
| * Caused by: java.lang.Exception: I did it |
| * at Foo3.main(Foo3.java:8) |
| * </pre> |
| * Likewise, a suppressed exception can have a cause: |
| * <pre> |
| * Exception in thread "main" java.lang.Exception: Main block |
| * at Foo4.main(Foo4.java:6) |
| * Suppressed: Resource2$CloseFailException: Resource ID = 1 |
| * at Resource2.close(Resource2.java:20) |
| * at Foo4.main(Foo4.java:5) |
| * Caused by: java.lang.Exception: Rats, you caught me |
| * at Resource2$CloseFailException.<init>(Resource2.java:45) |
| * ... 2 more |
| * </pre> |
| */ |
| public void printStackTrace() { |
| printStackTrace(System.err); |
| } |
| |
| /** |
| * Prints this throwable and its backtrace to the specified print stream. |
| * |
| * @param s {@code PrintStream} to use for output |
| */ |
| public void printStackTrace(PrintStream s) { |
| printStackTrace(new WrappedPrintStream(s)); |
| } |
| |
| private void printStackTrace(PrintStreamOrWriter s) { |
| // Guard against malicious overrides of Throwable.equals by |
| // using a Set with identity equality semantics. |
| Set<Throwable> dejaVu = |
| Collections.newSetFromMap(new IdentityHashMap<Throwable, Boolean>()); |
| dejaVu.add(this); |
| |
| synchronized (s.lock()) { |
| // Print our stack trace |
| s.println(this); |
| StackTraceElement[] trace = getOurStackTrace(); |
| for (StackTraceElement traceElement : trace) |
| s.println("\tat " + traceElement); |
| |
| // Print suppressed exceptions, if any |
| for (Throwable se : getSuppressed()) |
| se.printEnclosedStackTrace(s, trace, SUPPRESSED_CAPTION, "\t", dejaVu); |
| |
| // Print cause, if any |
| Throwable ourCause = getCause(); |
| if (ourCause != null) |
| ourCause.printEnclosedStackTrace(s, trace, CAUSE_CAPTION, "", dejaVu); |
| } |
| } |
| |
| /** |
| * Print our stack trace as an enclosed exception for the specified |
| * stack trace. |
| */ |
| private void printEnclosedStackTrace(PrintStreamOrWriter s, |
| StackTraceElement[] enclosingTrace, |
| String caption, |
| String prefix, |
| Set<Throwable> dejaVu) { |
| // Android-removed: Use of assert keyword which breaks serialization of some subclasses |
| // (Using assert adds a static field that determines whether assertions are enabled.) |
| // assert Thread.holdsLock(s.lock()); |
| if (dejaVu.contains(this)) { |
| s.println("\t[CIRCULAR REFERENCE:" + this + "]"); |
| } else { |
| dejaVu.add(this); |
| // Compute number of frames in common between this and enclosing trace |
| StackTraceElement[] trace = getOurStackTrace(); |
| int m = trace.length - 1; |
| int n = enclosingTrace.length - 1; |
| while (m >= 0 && n >=0 && trace[m].equals(enclosingTrace[n])) { |
| m--; n--; |
| } |
| int framesInCommon = trace.length - 1 - m; |
| |
| // Print our stack trace |
| s.println(prefix + caption + this); |
| for (int i = 0; i <= m; i++) |
| s.println(prefix + "\tat " + trace[i]); |
| if (framesInCommon != 0) |
| s.println(prefix + "\t... " + framesInCommon + " more"); |
| |
| // Print suppressed exceptions, if any |
| for (Throwable se : getSuppressed()) |
| se.printEnclosedStackTrace(s, trace, SUPPRESSED_CAPTION, |
| prefix +"\t", dejaVu); |
| |
| // Print cause, if any |
| Throwable ourCause = getCause(); |
| if (ourCause != null) |
| ourCause.printEnclosedStackTrace(s, trace, CAUSE_CAPTION, prefix, dejaVu); |
| } |
| } |
| |
| /** |
| * Prints this throwable and its backtrace to the specified |
| * print writer. |
| * |
| * @param s {@code PrintWriter} to use for output |
| * @since JDK1.1 |
| */ |
| public void printStackTrace(PrintWriter s) { |
| printStackTrace(new WrappedPrintWriter(s)); |
| } |
| |
| /** |
| * Wrapper class for PrintStream and PrintWriter to enable a single |
| * implementation of printStackTrace. |
| */ |
| private abstract static class PrintStreamOrWriter { |
| /** Returns the object to be locked when using this StreamOrWriter */ |
| abstract Object lock(); |
| |
| /** Prints the specified string as a line on this StreamOrWriter */ |
| abstract void println(Object o); |
| } |
| |
| private static class WrappedPrintStream extends PrintStreamOrWriter { |
| private final PrintStream printStream; |
| |
| WrappedPrintStream(PrintStream printStream) { |
| this.printStream = printStream; |
| } |
| |
| Object lock() { |
| return printStream; |
| } |
| |
| void println(Object o) { |
| printStream.println(o); |
| } |
| } |
| |
| private static class WrappedPrintWriter extends PrintStreamOrWriter { |
| private final PrintWriter printWriter; |
| |
| WrappedPrintWriter(PrintWriter printWriter) { |
| this.printWriter = printWriter; |
| } |
| |
| Object lock() { |
| return printWriter; |
| } |
| |
| void println(Object o) { |
| printWriter.println(o); |
| } |
| } |
| |
| /** |
| * Fills in the execution stack trace. This method records within this |
| * {@code Throwable} object information about the current state of |
| * the stack frames for the current thread. |
| * |
| * <p>If the stack trace of this {@code Throwable} {@linkplain |
| * Throwable#Throwable(String, Throwable, boolean, boolean) is not |
| * writable}, calling this method has no effect. |
| * |
| * @return a reference to this {@code Throwable} instance. |
| * @see java.lang.Throwable#printStackTrace() |
| */ |
| public synchronized Throwable fillInStackTrace() { |
| if (stackTrace != null || |
| backtrace != null /* Out of protocol state */ ) { |
| // Android-changed: Use Android-specific nativeFillInStackTrace |
| // fillInStackTrace(0); |
| backtrace = nativeFillInStackTrace(); |
| // Android-changed: Use libcore.util.EmptyArray for the empty stack trace |
| // stackTrace = UNASSIGNED_STACK; |
| stackTrace = libcore.util.EmptyArray.STACK_TRACE_ELEMENT; |
| } |
| return this; |
| } |
| |
| // Android-changed: Use Android-specific nativeFillInStackTrace |
| // private native Throwable fillInStackTrace(int dummy); |
| @FastNative |
| private static native Object nativeFillInStackTrace(); |
| |
| /** |
| * Provides programmatic access to the stack trace information printed by |
| * {@link #printStackTrace()}. Returns an array of stack trace elements, |
| * each representing one stack frame. The zeroth element of the array |
| * (assuming the array's length is non-zero) represents the top of the |
| * stack, which is the last method invocation in the sequence. Typically, |
| * this is the point at which this throwable was created and thrown. |
| * The last element of the array (assuming the array's length is non-zero) |
| * represents the bottom of the stack, which is the first method invocation |
| * in the sequence. |
| * |
| * <p>Some virtual machines may, under some circumstances, omit one |
| * or more stack frames from the stack trace. In the extreme case, |
| * a virtual machine that has no stack trace information concerning |
| * this throwable is permitted to return a zero-length array from this |
| * method. Generally speaking, the array returned by this method will |
| * contain one element for every frame that would be printed by |
| * {@code printStackTrace}. Writes to the returned array do not |
| * affect future calls to this method. |
| * |
| * @return an array of stack trace elements representing the stack trace |
| * pertaining to this throwable. |
| * @since 1.4 |
| */ |
| public StackTraceElement[] getStackTrace() { |
| return getOurStackTrace().clone(); |
| } |
| |
| private synchronized StackTraceElement[] getOurStackTrace() { |
| // Initialize stack trace field with information from |
| // backtrace if this is the first call to this method |
| // Android-changed: Use libcore.util.EmptyArray for the empty stack trace |
| // if (stackTrace == UNASSIGNED_STACK || |
| if (stackTrace == libcore.util.EmptyArray.STACK_TRACE_ELEMENT || |
| (stackTrace == null && backtrace != null) /* Out of protocol state */) { |
| // BEGIN Android-changed: Use Android-specific nativeGetStackTrace |
| // int depth = getStackTraceDepth(); |
| // stackTrace = new StackTraceElement[depth]; |
| // for (int i=0; i < depth; i++) |
| // stackTrace[i] = getStackTraceElement(i); |
| stackTrace = nativeGetStackTrace(backtrace); |
| backtrace = null; |
| if (stackTrace == null) { |
| return libcore.util.EmptyArray.STACK_TRACE_ELEMENT; |
| } |
| // END Android-changed: Use Android-specific nativeGetStackTrace |
| } else if (stackTrace == null) { |
| // Android-changed: Use libcore.util.EmptyArray for the empty stack trace |
| // return UNASSIGNED_STACK; |
| return libcore.util.EmptyArray.STACK_TRACE_ELEMENT; |
| } |
| return stackTrace; |
| } |
| |
| /** |
| * Sets the stack trace elements that will be returned by |
| * {@link #getStackTrace()} and printed by {@link #printStackTrace()} |
| * and related methods. |
| * |
| * This method, which is designed for use by RPC frameworks and other |
| * advanced systems, allows the client to override the default |
| * stack trace that is either generated by {@link #fillInStackTrace()} |
| * when a throwable is constructed or deserialized when a throwable is |
| * read from a serialization stream. |
| * |
| * <p>If the stack trace of this {@code Throwable} {@linkplain |
| * Throwable#Throwable(String, Throwable, boolean, boolean) is not |
| * writable}, calling this method has no effect other than |
| * validating its argument. |
| * |
| * @param stackTrace the stack trace elements to be associated with |
| * this {@code Throwable}. The specified array is copied by this |
| * call; changes in the specified array after the method invocation |
| * returns will have no affect on this {@code Throwable}'s stack |
| * trace. |
| * |
| * @throws NullPointerException if {@code stackTrace} is |
| * {@code null} or if any of the elements of |
| * {@code stackTrace} are {@code null} |
| * |
| * @since 1.4 |
| */ |
| public void setStackTrace(StackTraceElement[] stackTrace) { |
| // Validate argument |
| StackTraceElement[] defensiveCopy = stackTrace.clone(); |
| for (int i = 0; i < defensiveCopy.length; i++) { |
| if (defensiveCopy[i] == null) |
| throw new NullPointerException("stackTrace[" + i + "]"); |
| } |
| |
| synchronized (this) { |
| if (this.stackTrace == null && // Immutable stack |
| backtrace == null) // Test for out of protocol state |
| return; |
| this.stackTrace = defensiveCopy; |
| } |
| } |
| |
| // Android-removed: Unused native method getStackTraceDepth() |
| // /** |
| // * Returns the number of elements in the stack trace (or 0 if the stack |
| // * trace is unavailable). |
| // * |
| // * package-protection for use by SharedSecrets. |
| // */ |
| // native int getStackTraceDepth(); |
| |
| /** |
| * Returns the specified element of the stack trace. |
| * |
| * package-protection for use by SharedSecrets. |
| * |
| * @param index index of the element to return. |
| * @throws IndexOutOfBoundsException if {@code index < 0 || |
| * index >= getStackTraceDepth() } |
| */ |
| // Android-changed: Use Android-specific nativeGetStackTrace |
| // native StackTraceElement getStackTraceElement(int index); |
| @FastNative |
| private static native StackTraceElement[] nativeGetStackTrace(Object stackState); |
| |
| |
| /** |
| * Reads a {@code Throwable} from a stream, enforcing |
| * well-formedness constraints on fields. Null entries and |
| * self-pointers are not allowed in the list of {@code |
| * suppressedExceptions}. Null entries are not allowed for stack |
| * trace elements. A null stack trace in the serial form results |
| * in a zero-length stack element array. A single-element stack |
| * trace whose entry is equal to {@code new StackTraceElement("", |
| * "", null, Integer.MIN_VALUE)} results in a {@code null} {@code |
| * stackTrace} field. |
| * |
| * Note that there are no constraints on the value the {@code |
| * cause} field can hold; both {@code null} and {@code this} are |
| * valid values for the field. |
| */ |
| private void readObject(ObjectInputStream s) |
| throws IOException, ClassNotFoundException { |
| s.defaultReadObject(); // read in all fields |
| if (suppressedExceptions != null) { |
| List<Throwable> suppressed = null; |
| if (suppressedExceptions.isEmpty()) { |
| // Use the sentinel for a zero-length list |
| // Android-changed: Use empty collection in place of SUPPRESSED_SENTINEL |
| // suppressed = SUPPRESSED_SENTINEL; |
| suppressed = Collections.emptyList(); |
| } else { // Copy Throwables to new list |
| suppressed = new ArrayList<>(1); |
| for (Throwable t : suppressedExceptions) { |
| // Enforce constraints on suppressed exceptions in |
| // case of corrupt or malicious stream. |
| if (t == null) |
| throw new NullPointerException(NULL_CAUSE_MESSAGE); |
| if (t == this) |
| throw new IllegalArgumentException(SELF_SUPPRESSION_MESSAGE); |
| suppressed.add(t); |
| } |
| } |
| suppressedExceptions = suppressed; |
| } // else a null suppressedExceptions field remains null |
| |
| /* |
| * For zero-length stack traces, use a clone of |
| * UNASSIGNED_STACK rather than UNASSIGNED_STACK itself to |
| * allow identity comparison against UNASSIGNED_STACK in |
| * getOurStackTrace. The identity of UNASSIGNED_STACK in |
| * stackTrace indicates to the getOurStackTrace method that |
| * the stackTrace needs to be constructed from the information |
| * in backtrace. |
| */ |
| if (stackTrace != null) { |
| if (stackTrace.length == 0) { |
| // Android-removed: clone() call not needed because of libcore.util.EmptyArray usage |
| // stackTrace = UNASSIGNED_STACK.clone(); |
| } else if (stackTrace.length == 1 && |
| // Check for the marker of an immutable stack trace |
| SentinelHolder.STACK_TRACE_ELEMENT_SENTINEL.equals(stackTrace[0])) { |
| stackTrace = null; |
| } else { // Verify stack trace elements are non-null. |
| for(StackTraceElement ste : stackTrace) { |
| if (ste == null) |
| throw new NullPointerException("null StackTraceElement in serial stream. "); |
| } |
| } |
| } else { |
| // A null stackTrace field in the serial form can result |
| // from an exception serialized without that field in |
| // older JDK releases; treat such exceptions as having |
| // empty stack traces. |
| // Android-changed: Directly create empty array instead of cloning UNASSIGNED_STACK |
| // stackTrace = UNASSIGNED_STACK.clone(); |
| stackTrace = new StackTraceElement[0]; |
| } |
| } |
| |
| /** |
| * Write a {@code Throwable} object to a stream. |
| * |
| * A {@code null} stack trace field is represented in the serial |
| * form as a one-element array whose element is equal to {@code |
| * new StackTraceElement("", "", null, Integer.MIN_VALUE)}. |
| */ |
| private synchronized void writeObject(ObjectOutputStream s) |
| throws IOException { |
| // Ensure that the stackTrace field is initialized to a |
| // non-null value, if appropriate. As of JDK 7, a null stack |
| // trace field is a valid value indicating the stack trace |
| // should not be set. |
| getOurStackTrace(); |
| |
| StackTraceElement[] oldStackTrace = stackTrace; |
| try { |
| if (stackTrace == null) |
| stackTrace = SentinelHolder.STACK_TRACE_SENTINEL; |
| s.defaultWriteObject(); |
| } finally { |
| stackTrace = oldStackTrace; |
| } |
| } |
| |
| /** |
| * Appends the specified exception to the exceptions that were |
| * suppressed in order to deliver this exception. This method is |
| * thread-safe and typically called (automatically and implicitly) |
| * by the {@code try}-with-resources statement. |
| * |
| * <p>The suppression behavior is enabled <em>unless</em> disabled |
| * {@linkplain #Throwable(String, Throwable, boolean, boolean) via |
| * a constructor}. When suppression is disabled, this method does |
| * nothing other than to validate its argument. |
| * |
| * <p>Note that when one exception {@linkplain |
| * #initCause(Throwable) causes} another exception, the first |
| * exception is usually caught and then the second exception is |
| * thrown in response. In other words, there is a causal |
| * connection between the two exceptions. |
| * |
| * In contrast, there are situations where two independent |
| * exceptions can be thrown in sibling code blocks, in particular |
| * in the {@code try} block of a {@code try}-with-resources |
| * statement and the compiler-generated {@code finally} block |
| * which closes the resource. |
| * |
| * In these situations, only one of the thrown exceptions can be |
| * propagated. In the {@code try}-with-resources statement, when |
| * there are two such exceptions, the exception originating from |
| * the {@code try} block is propagated and the exception from the |
| * {@code finally} block is added to the list of exceptions |
| * suppressed by the exception from the {@code try} block. As an |
| * exception unwinds the stack, it can accumulate multiple |
| * suppressed exceptions. |
| * |
| * <p>An exception may have suppressed exceptions while also being |
| * caused by another exception. Whether or not an exception has a |
| * cause is semantically known at the time of its creation, unlike |
| * whether or not an exception will suppress other exceptions |
| * which is typically only determined after an exception is |
| * thrown. |
| * |
| * <p>Note that programmer written code is also able to take |
| * advantage of calling this method in situations where there are |
| * multiple sibling exceptions and only one can be propagated. |
| * |
| * @param exception the exception to be added to the list of |
| * suppressed exceptions |
| * @throws IllegalArgumentException if {@code exception} is this |
| * throwable; a throwable cannot suppress itself. |
| * @throws NullPointerException if {@code exception} is {@code null} |
| * @since 1.7 |
| */ |
| public final synchronized void addSuppressed(Throwable exception) { |
| if (exception == this) |
| throw new IllegalArgumentException(SELF_SUPPRESSION_MESSAGE, exception); |
| |
| if (exception == null) |
| throw new NullPointerException(NULL_CAUSE_MESSAGE); |
| |
| if (suppressedExceptions == null) // Suppressed exceptions not recorded |
| return; |
| |
| // Android-changed: Use empty collection in place of SUPPRESSED_SENTINEL |
| // if (suppressedExceptions == SUPPRESSED_SENTINEL) |
| if (suppressedExceptions.isEmpty()) |
| suppressedExceptions = new ArrayList<>(1); |
| |
| suppressedExceptions.add(exception); |
| } |
| |
| // Android-changed: Lazily initialize EMPTY_THROWABLE_ARRAY |
| // private static final Throwable[] EMPTY_THROWABLE_ARRAY = new Throwable[0]; |
| private static Throwable[] EMPTY_THROWABLE_ARRAY; |
| |
| /** |
| * Returns an array containing all of the exceptions that were |
| * suppressed, typically by the {@code try}-with-resources |
| * statement, in order to deliver this exception. |
| * |
| * If no exceptions were suppressed or {@linkplain |
| * #Throwable(String, Throwable, boolean, boolean) suppression is |
| * disabled}, an empty array is returned. This method is |
| * thread-safe. Writes to the returned array do not affect future |
| * calls to this method. |
| * |
| * @return an array containing all of the exceptions that were |
| * suppressed to deliver this exception. |
| * @since 1.7 |
| */ |
| public final synchronized Throwable[] getSuppressed() { |
| // Android-added: Lazily initialize EMPTY_THROWABLE_ARRAY |
| if (EMPTY_THROWABLE_ARRAY == null) { |
| EMPTY_THROWABLE_ARRAY = new Throwable[0]; |
| } |
| |
| // Android-changed: Use empty collection in place of SUPPRESSED_SENTINEL |
| // if (suppressedExceptions == SUPPRESSED_SENTINEL || |
| // suppressedExceptions == null) |
| if (suppressedExceptions == null || suppressedExceptions.isEmpty()) |
| return EMPTY_THROWABLE_ARRAY; |
| else |
| return suppressedExceptions.toArray(EMPTY_THROWABLE_ARRAY); |
| } |
| } |
