| /* |
| * 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 org.apache.commons.lang3.exception; |
| |
| import java.io.PrintStream; |
| import java.io.PrintWriter; |
| import java.io.StringWriter; |
| import java.lang.reflect.InvocationTargetException; |
| import java.lang.reflect.Method; |
| import java.lang.reflect.UndeclaredThrowableException; |
| import java.util.ArrayList; |
| import java.util.List; |
| import java.util.Objects; |
| import java.util.StringTokenizer; |
| |
| import org.apache.commons.lang3.ArrayUtils; |
| import org.apache.commons.lang3.ClassUtils; |
| import org.apache.commons.lang3.StringUtils; |
| |
| /** |
| * Provides utilities for manipulating and examining |
| * {@code Throwable} objects. |
| * |
| * @since 1.0 |
| */ |
| public class ExceptionUtils { |
| |
| private static final int NOT_FOUND = -1; |
| |
| /** |
| * The names of methods commonly used to access a wrapped exception. |
| */ |
| // TODO: Remove in Lang 4.0 |
| private static final String[] CAUSE_METHOD_NAMES = { |
| "getCause", |
| "getNextException", |
| "getTargetException", |
| "getException", |
| "getSourceException", |
| "getRootCause", |
| "getCausedByException", |
| "getNested", |
| "getLinkedException", |
| "getNestedException", |
| "getLinkedCause", |
| "getThrowable", |
| }; |
| |
| /** |
| * Used when printing stack frames to denote the start of a |
| * wrapped exception. |
| * |
| * <p>Package private for accessibility by test suite.</p> |
| */ |
| static final String WRAPPED_MARKER = " [wrapped] "; |
| |
| /** |
| * Claims a Throwable is another Throwable type using type erasure. This |
| * hides a checked exception from the Java compiler, allowing a checked |
| * exception to be thrown without having the exception in the method's throw |
| * clause. |
| */ |
| @SuppressWarnings("unchecked") |
| private static <R, T extends Throwable> R eraseType(final Throwable throwable) throws T { |
| throw (T) throwable; |
| } |
| |
| /** |
| * Introspects the {@code Throwable} to obtain the cause. |
| * |
| * <p>The method searches for methods with specific names that return a |
| * {@code Throwable} object. This will pick up most wrapping exceptions, |
| * including those from JDK 1.4. |
| * |
| * <p>The default list searched for are:</p> |
| * <ul> |
| * <li>{@code getCause()}</li> |
| * <li>{@code getNextException()}</li> |
| * <li>{@code getTargetException()}</li> |
| * <li>{@code getException()}</li> |
| * <li>{@code getSourceException()}</li> |
| * <li>{@code getRootCause()}</li> |
| * <li>{@code getCausedByException()}</li> |
| * <li>{@code getNested()}</li> |
| * </ul> |
| * |
| * <p>If none of the above is found, returns {@code null}.</p> |
| * |
| * @param throwable the throwable to introspect for a cause, may be null |
| * @return the cause of the {@code Throwable}, |
| * {@code null} if none found or null throwable input |
| * @since 1.0 |
| * @deprecated This feature will be removed in Lang 4.0, use {@link Throwable#getCause} instead |
| */ |
| @Deprecated |
| public static Throwable getCause(final Throwable throwable) { |
| return getCause(throwable, null); |
| } |
| |
| /** |
| * Introspects the {@code Throwable} to obtain the cause. |
| * |
| * <p>A {@code null} set of method names means use the default set. |
| * A {@code null} in the set of method names will be ignored.</p> |
| * |
| * @param throwable the throwable to introspect for a cause, may be null |
| * @param methodNames the method names, null treated as default set |
| * @return the cause of the {@code Throwable}, |
| * {@code null} if none found or null throwable input |
| * @since 1.0 |
| * @deprecated This feature will be removed in Lang 4.0, use {@link Throwable#getCause} instead |
| */ |
| @Deprecated |
| public static Throwable getCause(final Throwable throwable, String[] methodNames) { |
| if (throwable == null) { |
| return null; |
| } |
| |
| if (methodNames == null) { |
| final Throwable cause = throwable.getCause(); |
| if (cause != null) { |
| return cause; |
| } |
| |
| methodNames = CAUSE_METHOD_NAMES; |
| } |
| |
| for (final String methodName : methodNames) { |
| if (methodName != null) { |
| final Throwable legacyCause = getCauseUsingMethodName(throwable, methodName); |
| if (legacyCause != null) { |
| return legacyCause; |
| } |
| } |
| } |
| |
| return null; |
| } |
| |
| /** |
| * Gets a {@code Throwable} by method name. |
| * |
| * @param throwable the exception to examine |
| * @param methodName the name of the method to find and invoke |
| * @return the wrapped exception, or {@code null} if not found |
| */ |
| // TODO: Remove in Lang 4.0 |
| private static Throwable getCauseUsingMethodName(final Throwable throwable, final String methodName) { |
| Method method = null; |
| try { |
| method = throwable.getClass().getMethod(methodName); |
| } catch (final NoSuchMethodException | SecurityException ignored) { // NOPMD |
| // exception ignored |
| } |
| |
| if (method != null && Throwable.class.isAssignableFrom(method.getReturnType())) { |
| try { |
| return (Throwable) method.invoke(throwable); |
| } catch (final IllegalAccessException | IllegalArgumentException | InvocationTargetException ignored) { // NOPMD |
| // exception ignored |
| } |
| } |
| return null; |
| } |
| |
| /** |
| * Gets the default names used when searching for the cause of an exception. |
| * |
| * <p>This may be modified and used in the overloaded getCause(Throwable, String[]) method.</p> |
| * |
| * @return cloned array of the default method names |
| * @since 3.0 |
| * @deprecated This feature will be removed in Lang 4.0 |
| */ |
| @Deprecated |
| public static String[] getDefaultCauseMethodNames() { |
| return ArrayUtils.clone(CAUSE_METHOD_NAMES); |
| } |
| |
| /** |
| * Gets a short message summarising the exception. |
| * <p> |
| * The message returned is of the form |
| * {ClassNameWithoutPackage}: {ThrowableMessage} |
| * </p> |
| * |
| * @param th the throwable to get a message for, null returns empty string |
| * @return the message, non-null |
| * @since 2.2 |
| */ |
| public static String getMessage(final Throwable th) { |
| if (th == null) { |
| return StringUtils.EMPTY; |
| } |
| final String clsName = ClassUtils.getShortClassName(th, null); |
| final String msg = th.getMessage(); |
| return clsName + ": " + StringUtils.defaultString(msg); |
| } |
| |
| /** |
| * Introspects the {@code Throwable} to obtain the root cause. |
| * |
| * <p>This method walks through the exception chain to the last element, |
| * "root" of the tree, using {@link Throwable#getCause()}, and |
| * returns that exception.</p> |
| * |
| * <p>From version 2.2, this method handles recursive cause structures |
| * that might otherwise cause infinite loops. If the throwable parameter |
| * has a cause of itself, then null will be returned. If the throwable |
| * parameter cause chain loops, the last element in the chain before the |
| * loop is returned.</p> |
| * |
| * @param throwable the throwable to get the root cause for, may be null |
| * @return the root cause of the {@code Throwable}, |
| * {@code null} if null throwable input |
| */ |
| public static Throwable getRootCause(final Throwable throwable) { |
| final List<Throwable> list = getThrowableList(throwable); |
| return list.isEmpty() ? null : list.get(list.size() - 1); |
| } |
| |
| /** |
| * Gets a short message summarising the root cause exception. |
| * <p> |
| * The message returned is of the form |
| * {ClassNameWithoutPackage}: {ThrowableMessage} |
| * </p> |
| * |
| * @param th the throwable to get a message for, null returns empty string |
| * @return the message, non-null |
| * @since 2.2 |
| */ |
| public static String getRootCauseMessage(final Throwable th) { |
| Throwable root = getRootCause(th); |
| root = root == null ? th : root; |
| return getMessage(root); |
| } |
| |
| /** |
| * Gets a compact stack trace for the root cause of the supplied |
| * {@code Throwable}. |
| * |
| * <p>The output of this method is consistent across JDK versions. |
| * It consists of the root exception followed by each of its wrapping |
| * exceptions separated by '[wrapped]'. Note that this is the opposite |
| * order to the JDK1.4 display.</p> |
| * |
| * @param throwable the throwable to examine, may be null |
| * @return an array of stack trace frames, never null |
| * @since 2.0 |
| */ |
| public static String[] getRootCauseStackTrace(final Throwable throwable) { |
| if (throwable == null) { |
| return ArrayUtils.EMPTY_STRING_ARRAY; |
| } |
| final Throwable[] throwables = getThrowables(throwable); |
| final int count = throwables.length; |
| final List<String> frames = new ArrayList<>(); |
| List<String> nextTrace = getStackFrameList(throwables[count - 1]); |
| for (int i = count; --i >= 0;) { |
| final List<String> trace = nextTrace; |
| if (i != 0) { |
| nextTrace = getStackFrameList(throwables[i - 1]); |
| removeCommonFrames(trace, nextTrace); |
| } |
| if (i == count - 1) { |
| frames.add(throwables[i].toString()); |
| } else { |
| frames.add(WRAPPED_MARKER + throwables[i].toString()); |
| } |
| frames.addAll(trace); |
| } |
| return frames.toArray(ArrayUtils.EMPTY_STRING_ARRAY); |
| } |
| |
| /** |
| * Gets a {@code List} of stack frames - the message |
| * is not included. Only the trace of the specified exception is |
| * returned, any caused by trace is stripped. |
| * |
| * <p>This works in most cases - it will only fail if the exception |
| * message contains a line that starts with: |
| * {@code " at".}</p> |
| * |
| * @param t is any throwable |
| * @return List of stack frames |
| */ |
| static List<String> getStackFrameList(final Throwable t) { |
| final String stackTrace = getStackTrace(t); |
| final String linebreak = System.lineSeparator(); |
| final StringTokenizer frames = new StringTokenizer(stackTrace, linebreak); |
| final List<String> list = new ArrayList<>(); |
| boolean traceStarted = false; |
| while (frames.hasMoreTokens()) { |
| final String token = frames.nextToken(); |
| // Determine if the line starts with <whitespace>at |
| final int at = token.indexOf("at"); |
| if (at != NOT_FOUND && token.substring(0, at).trim().isEmpty()) { |
| traceStarted = true; |
| list.add(token); |
| } else if (traceStarted) { |
| break; |
| } |
| } |
| return list; |
| } |
| |
| /** |
| * Gets an array where each element is a line from the argument. |
| * |
| * <p>The end of line is determined by the value of {@link System#lineSeparator()}.</p> |
| * |
| * @param stackTrace a stack trace String |
| * @return an array where each element is a line from the argument |
| */ |
| static String[] getStackFrames(final String stackTrace) { |
| final String linebreak = System.lineSeparator(); |
| final StringTokenizer frames = new StringTokenizer(stackTrace, linebreak); |
| final List<String> list = new ArrayList<>(); |
| while (frames.hasMoreTokens()) { |
| list.add(frames.nextToken()); |
| } |
| return list.toArray(ArrayUtils.EMPTY_STRING_ARRAY); |
| } |
| |
| /** |
| * Gets the stack trace associated with the specified |
| * {@code Throwable} object, decomposing it into a list of |
| * stack frames. |
| * |
| * <p>The result of this method vary by JDK version as this method |
| * uses {@link Throwable#printStackTrace(java.io.PrintWriter)}. |
| * On JDK1.3 and earlier, the cause exception will not be shown |
| * unless the specified throwable alters printStackTrace.</p> |
| * |
| * @param throwable the {@code Throwable} to examine, may be null |
| * @return an array of strings describing each stack frame, never null |
| */ |
| public static String[] getStackFrames(final Throwable throwable) { |
| if (throwable == null) { |
| return ArrayUtils.EMPTY_STRING_ARRAY; |
| } |
| return getStackFrames(getStackTrace(throwable)); |
| } |
| |
| /** |
| * Gets the stack trace from a Throwable as a String. |
| * |
| * <p>The result of this method vary by JDK version as this method |
| * uses {@link Throwable#printStackTrace(java.io.PrintWriter)}. |
| * On JDK1.3 and earlier, the cause exception will not be shown |
| * unless the specified throwable alters printStackTrace.</p> |
| * |
| * @param throwable the {@code Throwable} to be examined |
| * @return the stack trace as generated by the exception's |
| * {@code printStackTrace(PrintWriter)} method |
| */ |
| public static String getStackTrace(final Throwable throwable) { |
| final StringWriter sw = new StringWriter(); |
| final PrintWriter pw = new PrintWriter(sw, true); |
| throwable.printStackTrace(pw); |
| return sw.getBuffer().toString(); |
| } |
| |
| /** |
| * Gets a count of the number of {@code Throwable} objects in the |
| * exception chain. |
| * |
| * <p>A throwable without cause will return {@code 1}. |
| * A throwable with one cause will return {@code 2} and so on. |
| * A {@code null} throwable will return {@code 0}.</p> |
| * |
| * <p>From version 2.2, this method handles recursive cause structures |
| * that might otherwise cause infinite loops. The cause chain is |
| * processed until the end is reached, or until the next item in the |
| * chain is already in the result set.</p> |
| * |
| * @param throwable the throwable to inspect, may be null |
| * @return the count of throwables, zero if null input |
| */ |
| public static int getThrowableCount(final Throwable throwable) { |
| return getThrowableList(throwable).size(); |
| } |
| |
| /** |
| * Gets the list of {@code Throwable} objects in the |
| * exception chain. |
| * |
| * <p>A throwable without cause will return a list containing |
| * one element - the input throwable. |
| * A throwable with one cause will return a list containing |
| * two elements. - the input throwable and the cause throwable. |
| * A {@code null} throwable will return a list of size zero.</p> |
| * |
| * <p>This method handles recursive cause structures that might |
| * otherwise cause infinite loops. The cause chain is processed until |
| * the end is reached, or until the next item in the chain is already |
| * in the result set.</p> |
| * |
| * @param throwable the throwable to inspect, may be null |
| * @return the list of throwables, never null |
| * @since 2.2 |
| */ |
| public static List<Throwable> getThrowableList(Throwable throwable) { |
| final List<Throwable> list = new ArrayList<>(); |
| while (throwable != null && !list.contains(throwable)) { |
| list.add(throwable); |
| throwable = throwable.getCause(); |
| } |
| return list; |
| } |
| |
| /** |
| * Gets the list of {@code Throwable} objects in the |
| * exception chain. |
| * |
| * <p>A throwable without cause will return an array containing |
| * one element - the input throwable. |
| * A throwable with one cause will return an array containing |
| * two elements. - the input throwable and the cause throwable. |
| * A {@code null} throwable will return an array of size zero.</p> |
| * |
| * <p>From version 2.2, this method handles recursive cause structures |
| * that might otherwise cause infinite loops. The cause chain is |
| * processed until the end is reached, or until the next item in the |
| * chain is already in the result set.</p> |
| * |
| * @see #getThrowableList(Throwable) |
| * @param throwable the throwable to inspect, may be null |
| * @return the array of throwables, never null |
| */ |
| public static Throwable[] getThrowables(final Throwable throwable) { |
| final List<Throwable> list = getThrowableList(throwable); |
| return list.toArray(ArrayUtils.EMPTY_THROWABLE_ARRAY); |
| } |
| |
| /** |
| * Tests if the throwable's causal chain have an immediate or wrapped exception |
| * of the given type? |
| * |
| * @param chain |
| * The root of a Throwable causal chain. |
| * @param type |
| * The exception type to test. |
| * @return true, if chain is an instance of type or is an |
| * UndeclaredThrowableException wrapping a cause. |
| * @since 3.5 |
| * @see #wrapAndThrow(Throwable) |
| */ |
| public static boolean hasCause(Throwable chain, |
| final Class<? extends Throwable> type) { |
| if (chain instanceof UndeclaredThrowableException) { |
| chain = chain.getCause(); |
| } |
| return type.isInstance(chain); |
| } |
| |
| /** |
| * Worker method for the {@code indexOfType} methods. |
| * |
| * @param throwable the throwable to inspect, may be null |
| * @param type the type to search for, subclasses match, null returns -1 |
| * @param fromIndex the (zero-based) index of the starting position, |
| * negative treated as zero, larger than chain size returns -1 |
| * @param subclass if {@code true}, compares with {@link Class#isAssignableFrom(Class)}, otherwise compares |
| * using references |
| * @return index of the {@code type} within throwables nested within the specified {@code throwable} |
| */ |
| private static int indexOf(final Throwable throwable, final Class<? extends Throwable> type, int fromIndex, final boolean subclass) { |
| if (throwable == null || type == null) { |
| return NOT_FOUND; |
| } |
| if (fromIndex < 0) { |
| fromIndex = 0; |
| } |
| final Throwable[] throwables = getThrowables(throwable); |
| if (fromIndex >= throwables.length) { |
| return NOT_FOUND; |
| } |
| if (subclass) { |
| for (int i = fromIndex; i < throwables.length; i++) { |
| if (type.isAssignableFrom(throwables[i].getClass())) { |
| return i; |
| } |
| } |
| } else { |
| for (int i = fromIndex; i < throwables.length; i++) { |
| if (type.equals(throwables[i].getClass())) { |
| return i; |
| } |
| } |
| } |
| return NOT_FOUND; |
| } |
| |
| /** |
| * Returns the (zero-based) index of the first {@code Throwable} |
| * that matches the specified class (exactly) in the exception chain. |
| * Subclasses of the specified class do not match - see |
| * {@link #indexOfType(Throwable, Class)} for the opposite. |
| * |
| * <p>A {@code null} throwable returns {@code -1}. |
| * A {@code null} type returns {@code -1}. |
| * No match in the chain returns {@code -1}.</p> |
| * |
| * @param throwable the throwable to inspect, may be null |
| * @param clazz the class to search for, subclasses do not match, null returns -1 |
| * @return the index into the throwable chain, -1 if no match or null input |
| */ |
| public static int indexOfThrowable(final Throwable throwable, final Class<? extends Throwable> clazz) { |
| return indexOf(throwable, clazz, 0, false); |
| } |
| |
| /** |
| * Returns the (zero-based) index of the first {@code Throwable} |
| * that matches the specified type in the exception chain from |
| * a specified index. |
| * Subclasses of the specified class do not match - see |
| * {@link #indexOfType(Throwable, Class, int)} for the opposite. |
| * |
| * <p>A {@code null} throwable returns {@code -1}. |
| * A {@code null} type returns {@code -1}. |
| * No match in the chain returns {@code -1}. |
| * A negative start index is treated as zero. |
| * A start index greater than the number of throwables returns {@code -1}.</p> |
| * |
| * @param throwable the throwable to inspect, may be null |
| * @param clazz the class to search for, subclasses do not match, null returns -1 |
| * @param fromIndex the (zero-based) index of the starting position, |
| * negative treated as zero, larger than chain size returns -1 |
| * @return the index into the throwable chain, -1 if no match or null input |
| */ |
| public static int indexOfThrowable(final Throwable throwable, final Class<? extends Throwable> clazz, final int fromIndex) { |
| return indexOf(throwable, clazz, fromIndex, false); |
| } |
| |
| /** |
| * Returns the (zero-based) index of the first {@code Throwable} |
| * that matches the specified class or subclass in the exception chain. |
| * Subclasses of the specified class do match - see |
| * {@link #indexOfThrowable(Throwable, Class)} for the opposite. |
| * |
| * <p>A {@code null} throwable returns {@code -1}. |
| * A {@code null} type returns {@code -1}. |
| * No match in the chain returns {@code -1}.</p> |
| * |
| * @param throwable the throwable to inspect, may be null |
| * @param type the type to search for, subclasses match, null returns -1 |
| * @return the index into the throwable chain, -1 if no match or null input |
| * @since 2.1 |
| */ |
| public static int indexOfType(final Throwable throwable, final Class<? extends Throwable> type) { |
| return indexOf(throwable, type, 0, true); |
| } |
| |
| /** |
| * Returns the (zero-based) index of the first {@code Throwable} |
| * that matches the specified type in the exception chain from |
| * a specified index. |
| * Subclasses of the specified class do match - see |
| * {@link #indexOfThrowable(Throwable, Class)} for the opposite. |
| * |
| * <p>A {@code null} throwable returns {@code -1}. |
| * A {@code null} type returns {@code -1}. |
| * No match in the chain returns {@code -1}. |
| * A negative start index is treated as zero. |
| * A start index greater than the number of throwables returns {@code -1}.</p> |
| * |
| * @param throwable the throwable to inspect, may be null |
| * @param type the type to search for, subclasses match, null returns -1 |
| * @param fromIndex the (zero-based) index of the starting position, |
| * negative treated as zero, larger than chain size returns -1 |
| * @return the index into the throwable chain, -1 if no match or null input |
| * @since 2.1 |
| */ |
| public static int indexOfType(final Throwable throwable, final Class<? extends Throwable> type, final int fromIndex) { |
| return indexOf(throwable, type, fromIndex, true); |
| } |
| |
| /** |
| * Prints a compact stack trace for the root cause of a throwable |
| * to {@code System.err}. |
| * |
| * <p>The compact stack trace starts with the root cause and prints |
| * stack frames up to the place where it was caught and wrapped. |
| * Then it prints the wrapped exception and continues with stack frames |
| * until the wrapper exception is caught and wrapped again, etc.</p> |
| * |
| * <p>The output of this method is consistent across JDK versions. |
| * Note that this is the opposite order to the JDK1.4 display.</p> |
| * |
| * <p>The method is equivalent to {@code printStackTrace} for throwables |
| * that don't have nested causes.</p> |
| * |
| * @param throwable the throwable to output |
| * @since 2.0 |
| */ |
| public static void printRootCauseStackTrace(final Throwable throwable) { |
| printRootCauseStackTrace(throwable, System.err); |
| } |
| |
| /** |
| * Prints a compact stack trace for the root cause of a throwable. |
| * |
| * <p>The compact stack trace starts with the root cause and prints |
| * stack frames up to the place where it was caught and wrapped. |
| * Then it prints the wrapped exception and continues with stack frames |
| * until the wrapper exception is caught and wrapped again, etc.</p> |
| * |
| * <p>The output of this method is consistent across JDK versions. |
| * Note that this is the opposite order to the JDK1.4 display.</p> |
| * |
| * <p>The method is equivalent to {@code printStackTrace} for throwables |
| * that don't have nested causes.</p> |
| * |
| * @param throwable the throwable to output, may be null |
| * @param printStream the stream to output to, may not be null |
| * @throws NullPointerException if the printStream is {@code null} |
| * @since 2.0 |
| */ |
| @SuppressWarnings("resource") |
| public static void printRootCauseStackTrace(final Throwable throwable, final PrintStream printStream) { |
| if (throwable == null) { |
| return; |
| } |
| Objects.requireNonNull(printStream, "printStream"); |
| final String[] trace = getRootCauseStackTrace(throwable); |
| for (final String element : trace) { |
| printStream.println(element); |
| } |
| printStream.flush(); |
| } |
| |
| /** |
| * Prints a compact stack trace for the root cause of a throwable. |
| * |
| * <p>The compact stack trace starts with the root cause and prints |
| * stack frames up to the place where it was caught and wrapped. |
| * Then it prints the wrapped exception and continues with stack frames |
| * until the wrapper exception is caught and wrapped again, etc.</p> |
| * |
| * <p>The output of this method is consistent across JDK versions. |
| * Note that this is the opposite order to the JDK1.4 display.</p> |
| * |
| * <p>The method is equivalent to {@code printStackTrace} for throwables |
| * that don't have nested causes.</p> |
| * |
| * @param throwable the throwable to output, may be null |
| * @param printWriter the writer to output to, may not be null |
| * @throws NullPointerException if the printWriter is {@code null} |
| * @since 2.0 |
| */ |
| @SuppressWarnings("resource") |
| public static void printRootCauseStackTrace(final Throwable throwable, final PrintWriter printWriter) { |
| if (throwable == null) { |
| return; |
| } |
| Objects.requireNonNull(printWriter, "printWriter"); |
| final String[] trace = getRootCauseStackTrace(throwable); |
| for (final String element : trace) { |
| printWriter.println(element); |
| } |
| printWriter.flush(); |
| } |
| |
| /** |
| * Removes common frames from the cause trace given the two stack traces. |
| * |
| * @param causeFrames stack trace of a cause throwable |
| * @param wrapperFrames stack trace of a wrapper throwable |
| * @throws IllegalArgumentException if either argument is null |
| * @since 2.0 |
| */ |
| public static void removeCommonFrames(final List<String> causeFrames, final List<String> wrapperFrames) { |
| if (causeFrames == null || wrapperFrames == null) { |
| throw new IllegalArgumentException("The List must not be null"); |
| } |
| int causeFrameIndex = causeFrames.size() - 1; |
| int wrapperFrameIndex = wrapperFrames.size() - 1; |
| while (causeFrameIndex >= 0 && wrapperFrameIndex >= 0) { |
| // Remove the frame from the cause trace if it is the same |
| // as in the wrapper trace |
| final String causeFrame = causeFrames.get(causeFrameIndex); |
| final String wrapperFrame = wrapperFrames.get(wrapperFrameIndex); |
| if (causeFrame.equals(wrapperFrame)) { |
| causeFrames.remove(causeFrameIndex); |
| } |
| causeFrameIndex--; |
| wrapperFrameIndex--; |
| } |
| } |
| |
| /** |
| * Throws a checked exception without adding the exception to the throws |
| * clause of the calling method. This method prevents throws clause |
| * pollution and reduces the clutter of "Caused by" exceptions in the |
| * stacktrace. |
| * <p> |
| * The use of this technique may be controversial, but exceedingly useful to |
| * library developers. |
| * </p> |
| * <pre> |
| * public int propagateExample { // note that there is no throws clause |
| * try { |
| * return invocation(); // throws IOException |
| * } catch (Exception e) { |
| * return ExceptionUtils.rethrow(e); // propagates a checked exception |
| * } |
| * } |
| * </pre> |
| * <p> |
| * This is an alternative to the more conservative approach of wrapping the |
| * checked exception in a RuntimeException: |
| * </p> |
| * <pre> |
| * public int wrapExample { // note that there is no throws clause |
| * try { |
| * return invocation(); // throws IOException |
| * } catch (Error e) { |
| * throw e; |
| * } catch (RuntimeException e) { |
| * throw e; // wraps a checked exception |
| * } catch (Exception e) { |
| * throw new UndeclaredThrowableException(e); // wraps a checked exception |
| * } |
| * } |
| * </pre> |
| * <p> |
| * One downside to using this approach is that the java compiler will not |
| * allow invoking code to specify a checked exception in a catch clause |
| * unless there is some code path within the try block that has invoked a |
| * method declared with that checked exception. If the invoking site wishes |
| * to catch the shaded checked exception, it must either invoke the shaded |
| * code through a method re-declaring the desired checked exception, or |
| * catch Exception and use the instanceof operator. Either of these |
| * techniques are required when interacting with non-java jvm code such as |
| * Jython, Scala, or Groovy, since these languages do not consider any |
| * exceptions as checked. |
| * </p> |
| * |
| * @param throwable |
| * The throwable to rethrow. |
| * @param <R> The type of the returned value. |
| * @return Never actually returned, this generic type matches any type |
| * which the calling site requires. "Returning" the results of this |
| * method, as done in the propagateExample above, will satisfy the |
| * java compiler requirement that all code paths return a value. |
| * @since 3.5 |
| * @see #wrapAndThrow(Throwable) |
| */ |
| public static <R> R rethrow(final Throwable throwable) { |
| // claim that the typeErasure invocation throws a RuntimeException |
| return ExceptionUtils.<R, RuntimeException>eraseType(throwable); |
| } |
| |
| /** |
| * Worker method for the {@code throwableOfType} methods. |
| * |
| * @param <T> the type of Throwable you are searching. |
| * @param throwable the throwable to inspect, may be null |
| * @param type the type to search, subclasses match, null returns null |
| * @param fromIndex the (zero-based) index of the starting position, |
| * negative treated as zero, larger than chain size returns null |
| * @param subclass if {@code true}, compares with {@link Class#isAssignableFrom(Class)}, otherwise compares |
| * using references |
| * @return throwable of the {@code type} within throwables nested within the specified {@code throwable} |
| */ |
| private static <T extends Throwable> T throwableOf(final Throwable throwable, final Class<T> type, int fromIndex, final boolean subclass) { |
| if (throwable == null || type == null) { |
| return null; |
| } |
| if (fromIndex < 0) { |
| fromIndex = 0; |
| } |
| final Throwable[] throwables = getThrowables(throwable); |
| if (fromIndex >= throwables.length) { |
| return null; |
| } |
| if (subclass) { |
| for (int i = fromIndex; i < throwables.length; i++) { |
| if (type.isAssignableFrom(throwables[i].getClass())) { |
| return type.cast(throwables[i]); |
| } |
| } |
| } else { |
| for (int i = fromIndex; i < throwables.length; i++) { |
| if (type.equals(throwables[i].getClass())) { |
| return type.cast(throwables[i]); |
| } |
| } |
| } |
| return null; |
| } |
| |
| /** |
| * Returns the first {@code Throwable} |
| * that matches the specified class (exactly) in the exception chain. |
| * Subclasses of the specified class do not match - see |
| * {@link #throwableOfType(Throwable, Class)} for the opposite. |
| * |
| * <p>A {@code null} throwable returns {@code null}. |
| * A {@code null} type returns {@code null}. |
| * No match in the chain returns {@code null}.</p> |
| * |
| * @param <T> the type of Throwable you are searching. |
| * @param throwable the throwable to inspect, may be null |
| * @param clazz the class to search for, subclasses do not match, null returns null |
| * @return the first matching throwable from the throwable chain, null if no match or null input |
| * @since 3.10 |
| */ |
| public static <T extends Throwable> T throwableOfThrowable(final Throwable throwable, final Class<T> clazz) { |
| return throwableOf(throwable, clazz, 0, false); |
| } |
| |
| /** |
| * Returns the first {@code Throwable} |
| * that matches the specified type in the exception chain from |
| * a specified index. |
| * Subclasses of the specified class do not match - see |
| * {@link #throwableOfType(Throwable, Class, int)} for the opposite. |
| * |
| * <p>A {@code null} throwable returns {@code null}. |
| * A {@code null} type returns {@code null}. |
| * No match in the chain returns {@code null}. |
| * A negative start index is treated as zero. |
| * A start index greater than the number of throwables returns {@code null}.</p> |
| * |
| * @param <T> the type of Throwable you are searching. |
| * @param throwable the throwable to inspect, may be null |
| * @param clazz the class to search for, subclasses do not match, null returns null |
| * @param fromIndex the (zero-based) index of the starting position, |
| * negative treated as zero, larger than chain size returns null |
| * @return the first matching throwable from the throwable chain, null if no match or null input |
| * @since 3.10 |
| */ |
| public static <T extends Throwable> T throwableOfThrowable(final Throwable throwable, final Class<T> clazz, final int fromIndex) { |
| return throwableOf(throwable, clazz, fromIndex, false); |
| } |
| |
| /** |
| * Returns the throwable of the first {@code Throwable} |
| * that matches the specified class or subclass in the exception chain. |
| * Subclasses of the specified class do match - see |
| * {@link #throwableOfThrowable(Throwable, Class)} for the opposite. |
| * |
| * <p>A {@code null} throwable returns {@code null}. |
| * A {@code null} type returns {@code null}. |
| * No match in the chain returns {@code null}.</p> |
| * |
| * @param <T> the type of Throwable you are searching. |
| * @param throwable the throwable to inspect, may be null |
| * @param type the type to search for, subclasses match, null returns null |
| * @return the first matching throwable from the throwable chain, null if no match or null input |
| * @since 3.10 |
| */ |
| public static <T extends Throwable> T throwableOfType(final Throwable throwable, final Class<T> type) { |
| return throwableOf(throwable, type, 0, true); |
| } |
| |
| /** |
| * Returns the first {@code Throwable} |
| * that matches the specified type in the exception chain from |
| * a specified index. |
| * Subclasses of the specified class do match - see |
| * {@link #throwableOfThrowable(Throwable, Class)} for the opposite. |
| * |
| * <p>A {@code null} throwable returns {@code null}. |
| * A {@code null} type returns {@code null}. |
| * No match in the chain returns {@code null}. |
| * A negative start index is treated as zero. |
| * A start index greater than the number of throwables returns {@code null}.</p> |
| * |
| * @param <T> the type of Throwable you are searching. |
| * @param throwable the throwable to inspect, may be null |
| * @param type the type to search for, subclasses match, null returns null |
| * @param fromIndex the (zero-based) index of the starting position, |
| * negative treated as zero, larger than chain size returns null |
| * @return the first matching throwable from the throwable chain, null if no match or null input |
| * @since 3.10 |
| */ |
| public static <T extends Throwable> T throwableOfType(final Throwable throwable, final Class<T> type, final int fromIndex) { |
| return throwableOf(throwable, type, fromIndex, true); |
| } |
| |
| /** |
| * Throws a checked exception without adding the exception to the throws |
| * clause of the calling method. For checked exceptions, this method throws |
| * an UndeclaredThrowableException wrapping the checked exception. For |
| * Errors and RuntimeExceptions, the original exception is rethrown. |
| * <p> |
| * The downside to using this approach is that invoking code which needs to |
| * handle specific checked exceptions must sniff up the exception chain to |
| * determine if the caught exception was caused by the checked exception. |
| * </p> |
| * |
| * @param throwable |
| * The throwable to rethrow. |
| * @param <R> The type of the returned value. |
| * @return Never actually returned, this generic type matches any type |
| * which the calling site requires. "Returning" the results of this |
| * method will satisfy the java compiler requirement that all code |
| * paths return a value. |
| * @since 3.5 |
| * @see #rethrow(Throwable) |
| * @see #hasCause(Throwable, Class) |
| */ |
| public static <R> R wrapAndThrow(final Throwable throwable) { |
| if (throwable instanceof RuntimeException) { |
| throw (RuntimeException) throwable; |
| } |
| if (throwable instanceof Error) { |
| throw (Error) throwable; |
| } |
| throw new UndeclaredThrowableException(throwable); |
| } |
| |
| /** |
| * Public constructor allows an instance of {@code ExceptionUtils} to be created, although that is not |
| * normally necessary. |
| */ |
| public ExceptionUtils() { |
| } |
| } |