| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package java.lang; |
| |
| import java.io.IOException; |
| import java.io.ObjectOutputStream; |
| import java.io.PrintStream; |
| import java.io.PrintWriter; |
| |
| /** |
| * The superclass of all classes which can be thrown by the virtual machine. The |
| * two direct subclasses are recoverable exceptions ({@code Exception}) and |
| * unrecoverable errors ({@code Error}). This class provides common methods for |
| * accessing a string message which provides extra information about the |
| * circumstances in which the {@code Throwable} was created (basically an error |
| * message in most cases), and for saving a stack trace (that is, a record of |
| * the call stack at a particular point in time) which can be printed later. |
| * <p> |
| * A {@code Throwable} can also include a cause, which is a nested {@code |
| * Throwable} that represents the original problem that led to this {@code |
| * Throwable}. It is often used for wrapping various types of errors into a |
| * common {@code Throwable} without losing the detailed original error |
| * information. When printing the stack trace, the trace of the cause is |
| * included. |
| * |
| * @see Error |
| * @see Exception |
| * @see RuntimeException |
| */ |
| public class Throwable implements java.io.Serializable { |
| private static final long serialVersionUID = -3042686055658047285L; |
| |
| /** |
| * The message provided when the exception was created. |
| */ |
| private String detailMessage; |
| |
| /** |
| * The cause of this Throwable. Null when there is no cause. |
| */ |
| private Throwable cause = this; |
| |
| /** |
| * An intermediate representation of the stack trace. This field may |
| * be accessed by the VM; do not rename. |
| */ |
| private volatile Object stackState; |
| |
| /** |
| * A fully-expanded representation of the stack trace. |
| */ |
| private StackTraceElement[] stackTrace; |
| |
| /** |
| * Constructs a new {@code Throwable} that includes the current stack trace. |
| */ |
| public Throwable() { |
| super(); |
| fillInStackTrace(); |
| } |
| |
| /** |
| * Constructs a new {@code Throwable} with the current stack trace and the |
| * specified detail message. |
| * |
| * @param detailMessage |
| * the detail message for this {@code Throwable}. |
| */ |
| public Throwable(String detailMessage) { |
| this(); |
| this.detailMessage = detailMessage; |
| } |
| |
| /** |
| * Constructs a new {@code Throwable} with the current stack trace, the |
| * specified detail message and the specified cause. |
| * |
| * @param detailMessage |
| * the detail message for this {@code Throwable}. |
| * @param throwable |
| * the cause of this {@code Throwable}. |
| */ |
| public Throwable(String detailMessage, Throwable throwable) { |
| this(); |
| this.detailMessage = detailMessage; |
| cause = throwable; |
| } |
| |
| /** |
| * Constructs a new {@code Throwable} with the current stack trace and the |
| * specified cause. |
| * |
| * @param throwable |
| * the cause of this {@code Throwable}. |
| */ |
| public Throwable(Throwable throwable) { |
| this(); |
| this.detailMessage = throwable == null ? null : throwable.toString(); |
| cause = throwable; |
| } |
| |
| /** |
| * Records the stack trace from the point where this method has been called |
| * to this {@code Throwable}. This method is invoked by the {@code Throwable} constructors. |
| * |
| * <p>This method is public so that code (such as an RPC system) which catches |
| * a {@code Throwable} and then re-throws it can replace the construction-time stack trace |
| * with a stack trace from the location where the exception was re-thrown, by <i>calling</i> |
| * {@code fillInStackTrace}. |
| * |
| * <p>This method is non-final so that non-Java language implementations can disable VM stack |
| * traces for their language. Filling in the stack trace is relatively expensive. |
| * <i>Overriding</i> this method in the root of a language's exception hierarchy allows the |
| * language to avoid paying for something it doesn't need. |
| * |
| * @return this {@code Throwable} instance. |
| */ |
| public Throwable fillInStackTrace() { |
| // Fill in the intermediate representation |
| stackState = nativeFillInStackTrace(); |
| // Mark the full representation as empty |
| stackTrace = null; |
| return this; |
| } |
| |
| /** |
| * Returns the extra information message which was provided when this |
| * {@code Throwable} was created. Returns {@code null} if no message was |
| * provided at creation time. |
| * |
| * @return this {@code Throwable}'s detail message. |
| */ |
| public String getMessage() { |
| return detailMessage; |
| } |
| |
| /** |
| * Returns the extra information message which was provided when this |
| * {@code Throwable} was created. Returns {@code null} if no message was |
| * provided at creation time. Subclasses may override this method to return |
| * localized text for the message. Android returns the regular detail message. |
| * |
| * @return this {@code Throwable}'s localized detail message. |
| */ |
| public String getLocalizedMessage() { |
| return getMessage(); |
| } |
| |
| /** |
| * Returns the array of stack trace elements of this {@code Throwable}. Each |
| * {@code StackTraceElement} represents an entry in the call stack. The |
| * element at position 0 is the top of the stack, that is, the stack frame |
| * where this {@code Throwable} is thrown. |
| * |
| * @return a copy of the array of {@code StackTraceElement}s representing |
| * the call stack. Changes in the array obtained from this call will |
| * not change the call stack stored in this {@code Throwable}. |
| * @see #printStackTrace() |
| */ |
| public StackTraceElement[] getStackTrace() { |
| return getInternalStackTrace().clone(); |
| } |
| |
| /** |
| * Sets the array of stack trace elements. Each {@code StackTraceElement} |
| * represents an entry in the call stack. A copy of the specified array is |
| * stored in this {@code Throwable}. will be returned by {@code |
| * getStackTrace()} and printed by {@code printStackTrace()}. |
| * |
| * @param trace |
| * the new array of {@code StackTraceElement}s. A copy of the |
| * array is stored in this {@code Throwable}, so subsequent |
| * changes to {@code trace} will not change the call stack stored |
| * in this {@code Throwable}. |
| * @throws NullPointerException |
| * if any element in {@code trace} is {@code null}. |
| * @see #printStackTrace() |
| */ |
| public void setStackTrace(StackTraceElement[] trace) { |
| StackTraceElement[] newTrace = trace.clone(); |
| for (StackTraceElement element : newTrace) { |
| if (element == null) { |
| throw new NullPointerException(); |
| } |
| } |
| stackTrace = newTrace; |
| } |
| |
| /** |
| * Writes a printable representation of this {@code Throwable}'s stack trace |
| * to the {@code System.err} stream. |
| * |
| */ |
| public void printStackTrace() { |
| printStackTrace(System.err); |
| } |
| |
| /** |
| * Counts the number of duplicate stack frames, starting from the |
| * end of the stack. |
| * |
| * @param currentStack a stack to compare |
| * @param parentStack a stack to compare |
| * |
| * @return the number of duplicate stack frames. |
| */ |
| private static int countDuplicates(StackTraceElement[] currentStack, |
| StackTraceElement[] parentStack) { |
| int duplicates = 0; |
| int parentIndex = parentStack.length; |
| for (int i = currentStack.length; --i >= 0 && --parentIndex >= 0;) { |
| StackTraceElement parentFrame = parentStack[parentIndex]; |
| if (parentFrame.equals(currentStack[i])) { |
| duplicates++; |
| } else { |
| break; |
| } |
| } |
| return duplicates; |
| } |
| |
| /** |
| * Returns an array of StackTraceElement. Each StackTraceElement |
| * represents a entry on the stack. |
| * |
| * @return an array of StackTraceElement representing the stack |
| */ |
| private StackTraceElement[] getInternalStackTrace() { |
| if (stackTrace == null) { |
| stackTrace = nativeGetStackTrace(stackState); |
| stackState = null; // Clean up intermediate representation |
| } |
| return stackTrace; |
| } |
| |
| /** |
| * Writes a printable representation of this {@code Throwable}'s stack trace |
| * to the specified print stream. If the {@code Throwable} contains a |
| * {@link #getCause() cause}, the method will be invoked recursively for |
| * the nested {@code Throwable}. |
| * |
| * @param err |
| * the stream to write the stack trace on. |
| */ |
| public void printStackTrace(PrintStream err) { |
| err.println(toString()); |
| // Don't use getStackTrace() as it calls clone() |
| // Get stackTrace, in case stackTrace is reassigned |
| StackTraceElement[] stack = getInternalStackTrace(); |
| if (stack != null) { |
| for (StackTraceElement element : stack) { |
| err.println("\tat " + element); |
| } |
| } |
| |
| StackTraceElement[] parentStack = stack; |
| Throwable throwable = getCause(); |
| while (throwable != null) { |
| err.print("Caused by: "); |
| err.println(throwable); |
| StackTraceElement[] currentStack = throwable.getInternalStackTrace(); |
| int duplicates = countDuplicates(currentStack, parentStack); |
| for (int i = 0; i < currentStack.length - duplicates; i++) { |
| err.println("\tat " + currentStack[i]); |
| } |
| if (duplicates > 0) { |
| err.println("\t... " + duplicates + " more"); |
| } |
| parentStack = currentStack; |
| throwable = throwable.getCause(); |
| } |
| } |
| |
| /** |
| * Writes a printable representation of this {@code Throwable}'s stack trace |
| * to the specified print writer. If the {@code Throwable} contains a |
| * {@link #getCause() cause}, the method will be invoked recursively for the |
| * nested {@code Throwable}. |
| * |
| * @param err |
| * the writer to write the stack trace on. |
| */ |
| public void printStackTrace(PrintWriter err) { |
| err.println(toString()); |
| // Don't use getStackTrace() as it calls clone() |
| // Get stackTrace, in case stackTrace is reassigned |
| StackTraceElement[] stack = getInternalStackTrace(); |
| if (stack != null) { |
| for (StackTraceElement element : stack) { |
| err.println("\tat " + element); |
| } |
| } |
| |
| StackTraceElement[] parentStack = stack; |
| Throwable throwable = getCause(); |
| while (throwable != null) { |
| err.print("Caused by: "); |
| err.println(throwable); |
| StackTraceElement[] currentStack = throwable.getInternalStackTrace(); |
| int duplicates = countDuplicates(currentStack, parentStack); |
| for (int i = 0; i < currentStack.length - duplicates; i++) { |
| err.println("\tat " + currentStack[i]); |
| } |
| if (duplicates > 0) { |
| err.println("\t... " + duplicates + " more"); |
| } |
| parentStack = currentStack; |
| throwable = throwable.getCause(); |
| } |
| } |
| |
| @Override |
| public String toString() { |
| String msg = getLocalizedMessage(); |
| String name = getClass().getName(); |
| if (msg == null) { |
| return name; |
| } |
| return name + ": " + msg; |
| } |
| |
| /** |
| * Initializes the cause of this {@code Throwable}. The cause can only be |
| * initialized once. |
| * |
| * @param throwable |
| * the cause of this {@code Throwable}. |
| * @return this {@code Throwable} instance. |
| * @throws IllegalArgumentException |
| * if {@code Throwable} is this object. |
| * @throws IllegalStateException |
| * if the cause has already been initialized. |
| */ |
| public Throwable initCause(Throwable throwable) { |
| if (cause == this) { |
| if (throwable != this) { |
| cause = throwable; |
| return this; |
| } |
| throw new IllegalArgumentException("Cause cannot be the receiver"); |
| } |
| throw new IllegalStateException("Cause already initialized"); |
| } |
| |
| /** |
| * Returns the cause of this {@code Throwable}, or {@code null} if there is |
| * no cause. |
| * |
| * @return Throwable this {@code Throwable}'s cause. |
| */ |
| public Throwable getCause() { |
| if (cause == this) { |
| return null; |
| } |
| return cause; |
| } |
| |
| private void writeObject(ObjectOutputStream s) throws IOException { |
| // ensure the stackTrace field is initialized |
| getInternalStackTrace(); |
| s.defaultWriteObject(); |
| } |
| |
| /* |
| * Creates a compact, VM-specific collection of goodies, suitable for |
| * storing in the "stackState" field, based on the current thread's |
| * call stack. |
| */ |
| private static native Object nativeFillInStackTrace(); |
| |
| /* |
| * Creates an array of StackTraceElement objects from the data held |
| * in "stackState". |
| */ |
| private static native StackTraceElement[] nativeGetStackTrace(Object stackState); |
| } |