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/*
 * 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.Collections;
import java.util.List;
import java.util.Objects;
import java.util.StringTokenizer;
import java.util.function.Consumer;
import java.util.stream.Stream;

import org.apache.commons.lang3.ArrayUtils;
import org.apache.commons.lang3.ClassUtils;
import org.apache.commons.lang3.StringUtils;

/**
 * Provides utilities for manipulating and examining
 * {@link Throwable} objects.
 *
 * @since 1.0
 */
public class ExceptionUtils {

    /**
     * The names of methods commonly used to access a wrapped exception.
     */
    // TODO: Remove in Lang 4
    private static final String[] CAUSE_METHOD_NAMES = {
        "getCause",
        "getNextException",
        "getTargetException",
        "getException",
        "getSourceException",
        "getRootCause",
        "getCausedByException",
        "getNested",
        "getLinkedException",
        "getNestedException",
        "getLinkedCause",
        "getThrowable",
    };

    private static final int NOT_FOUND = -1;

    /**
     * Used when printing stack frames to denote the start of a
     * wrapped exception.
     *
     * 

Package private for accessibility by test suite.

*/ 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 eraseType(final Throwable throwable) throws T { throw (T) throwable; } /** * Performs an action for each Throwable causes of the given Throwable. *

* A throwable without cause will return a stream containing one element - the input throwable. A throwable with one cause * will return a stream containing two elements. - the input throwable and the cause throwable. A {@code null} throwable * will return a stream of count zero. *

* *

* 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. *

* @param throwable The Throwable to traverse. * @param consumer a non-interfering action to perform on the elements. * @since 3.13.0 */ public static void forEach(final Throwable throwable, final Consumer consumer) { stream(throwable).forEach(consumer); } /** * Introspects the {@link Throwable} to obtain the cause. * *

The method searches for methods with specific names that return a * {@link Throwable} object. This will pick up most wrapping exceptions, * including those from JDK 1.4. *

* *

The default list searched for are:

*
    *
  • {@code getCause()}
  • *
  • {@code getNextException()}
  • *
  • {@code getTargetException()}
  • *
  • {@code getException()}
  • *
  • {@code getSourceException()}
  • *
  • {@code getRootCause()}
  • *
  • {@code getCausedByException()}
  • *
  • {@code getNested()}
  • *
* *

If none of the above is found, returns {@code null}.

* * @param throwable the throwable to introspect for a cause, may be null * @return the cause of the {@link Throwable}, * {@code null} if none found or null throwable input * @since 1.0 * @deprecated This feature will be removed in Lang 4, use {@link Throwable#getCause} instead */ @Deprecated public static Throwable getCause(final Throwable throwable) { return getCause(throwable, null); } /** * Introspects the {@link Throwable} to obtain the cause. * *

A {@code null} set of method names means use the default set. * A {@code null} in the set of method names will be ignored.

* * @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 {@link Throwable}, * {@code null} if none found or null throwable input * @since 1.0 * @deprecated This feature will be removed in Lang 4, 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; } return Stream.of(methodNames).map(m -> getCauseUsingMethodName(throwable, m)).filter(Objects::nonNull).findFirst().orElse(null); } /** * Gets a {@link 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 private static Throwable getCauseUsingMethodName(final Throwable throwable, final String methodName) { if (methodName != null) { Method method = null; try { method = throwable.getClass().getMethod(methodName); } catch (final NoSuchMethodException | SecurityException ignored) { // exception ignored } if (method != null && Throwable.class.isAssignableFrom(method.getReturnType())) { try { return (Throwable) method.invoke(throwable); } catch (final IllegalAccessException | IllegalArgumentException | InvocationTargetException ignored) { // exception ignored } } } return null; } /** * Gets the default names used when searching for the cause of an exception. * *

This may be modified and used in the overloaded getCause(Throwable, String[]) method.

* * @return cloned array of the default method names * @since 3.0 * @deprecated This feature will be removed in Lang 4 */ @Deprecated public static String[] getDefaultCauseMethodNames() { return ArrayUtils.clone(CAUSE_METHOD_NAMES); } /** * Gets a short message summarizing the exception. *

* The message returned is of the form * {ClassNameWithoutPackage}: {ThrowableMessage} *

* * @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); return clsName + ": " + StringUtils.defaultString(th.getMessage()); } /** * Introspects the {@link Throwable} to obtain the root cause. * *

This method walks through the exception chain to the last element, * "root" of the tree, using {@link Throwable#getCause()}, and * returns that exception.

* *

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.

* * @param throwable the throwable to get the root cause for, may be null * @return the root cause of the {@link Throwable}, * {@code null} if null throwable input */ public static Throwable getRootCause(final Throwable throwable) { final List list = getThrowableList(throwable); return list.isEmpty() ? null : list.get(list.size() - 1); } /** * Gets a short message summarizing the root cause exception. *

* The message returned is of the form * {ClassNameWithoutPackage}: {ThrowableMessage} *

* * @param throwable 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 throwable) { final Throwable root = getRootCause(throwable); return getMessage(root == null ? throwable : root); } /** * Gets a compact stack trace for the root cause of the supplied * {@link Throwable}. * *

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.

* * @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) { return getRootCauseStackTraceList(throwable).toArray(ArrayUtils.EMPTY_STRING_ARRAY); } /** * Gets a compact stack trace for the root cause of the supplied {@link Throwable}. * *

* 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. *

* * @param throwable the throwable to examine, may be null * @return a list of stack trace frames, never null * @since 3.13.0 */ public static List getRootCauseStackTraceList(final Throwable throwable) { if (throwable == null) { return Collections.emptyList(); } final Throwable[] throwables = getThrowables(throwable); final int count = throwables.length; final List frames = new ArrayList<>(); List nextTrace = getStackFrameList(throwables[count - 1]); for (int i = count; --i >= 0;) { final List 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; } /** * Gets a {@link List} of stack frames - the message * is not included. Only the trace of the specified exception is * returned, any caused by trace is stripped. * *

This works in most cases - it will only fail if the exception * message contains a line that starts with: * {@code "   at".}

* * @param throwable is any throwable * @return List of stack frames */ static List getStackFrameList(final Throwable throwable) { final String stackTrace = getStackTrace(throwable); final String linebreak = System.lineSeparator(); final StringTokenizer frames = new StringTokenizer(stackTrace, linebreak); final List list = new ArrayList<>(); boolean traceStarted = false; while (frames.hasMoreTokens()) { final String token = frames.nextToken(); // Determine if the line starts with 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. * *

The end of line is determined by the value of {@link System#lineSeparator()}.

* * @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 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 * {@link Throwable} object, decomposing it into a list of * stack frames. * *

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.

* * @param throwable the {@link 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. * *

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.

* * @param throwable the {@link Throwable} to be examined, may be null * @return the stack trace as generated by the exception's * {@code printStackTrace(PrintWriter)} method, or an empty String if {@code null} input */ public static String getStackTrace(final Throwable throwable) { if (throwable == null) { return StringUtils.EMPTY; } final StringWriter sw = new StringWriter(); throwable.printStackTrace(new PrintWriter(sw, true)); return sw.toString(); } /** * Gets a count of the number of {@link Throwable} objects in the * exception chain. * *

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}.

* *

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.

* * @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 {@link Throwable} objects in the * exception chain. * *

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.

* *

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.

* * @param throwable the throwable to inspect, may be null * @return the list of throwables, never null * @since 2.2 */ public static List getThrowableList(Throwable throwable) { final List list = new ArrayList<>(); while (throwable != null && !list.contains(throwable)) { list.add(throwable); throwable = throwable.getCause(); } return list; } /** * Gets the list of {@link Throwable} objects in the * exception chain. * *

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.

* *

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.

* * @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) { return getThrowableList(throwable).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 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 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 {@link 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. * *

A {@code null} throwable returns {@code -1}. * A {@code null} type returns {@code -1}. * No match in the chain returns {@code -1}.

* * @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 clazz) { return indexOf(throwable, clazz, 0, false); } /** * Returns the (zero-based) index of the first {@link 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. * *

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}.

* * @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 clazz, final int fromIndex) { return indexOf(throwable, clazz, fromIndex, false); } /** * Returns the (zero-based) index of the first {@link 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. * *

A {@code null} throwable returns {@code -1}. * A {@code null} type returns {@code -1}. * No match in the chain returns {@code -1}.

* * @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 type) { return indexOf(throwable, type, 0, true); } /** * Returns the (zero-based) index of the first {@link 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. * *

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}.

* * @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 type, final int fromIndex) { return indexOf(throwable, type, fromIndex, true); } /** * Checks if a throwable represents a checked exception * * @param throwable * The throwable to check. * @return True if the given Throwable is a checked exception. * @since 3.13.0 */ public static boolean isChecked(final Throwable throwable) { return throwable != null && !(throwable instanceof Error) && !(throwable instanceof RuntimeException); } /** * Checks if a throwable represents an unchecked exception * * @param throwable * The throwable to check. * @return True if the given Throwable is an unchecked exception. * @since 3.13.0 */ public static boolean isUnchecked(final Throwable throwable) { return throwable != null && (throwable instanceof Error || throwable instanceof RuntimeException); } /** * Prints a compact stack trace for the root cause of a throwable * to {@code System.err}. * *

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.

* *

The output of this method is consistent across JDK versions. * Note that this is the opposite order to the JDK1.4 display.

* *

The method is equivalent to {@code printStackTrace} for throwables * that don't have nested causes.

* * @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. * *

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.

* *

The output of this method is consistent across JDK versions. * Note that this is the opposite order to the JDK1.4 display.

* *

The method is equivalent to {@code printStackTrace} for throwables * that don't have nested causes.

* * @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"); getRootCauseStackTraceList(throwable).forEach(printStream::println); printStream.flush(); } /** * Prints a compact stack trace for the root cause of a throwable. * *

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.

* *

The output of this method is consistent across JDK versions. * Note that this is the opposite order to the JDK1.4 display.

* *

The method is equivalent to {@code printStackTrace} for throwables * that don't have nested causes.

* * @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"); getRootCauseStackTraceList(throwable).forEach(printWriter::println); 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 NullPointerException if either argument is null * @since 2.0 */ public static void removeCommonFrames(final List causeFrames, final List wrapperFrames) { Objects.requireNonNull(causeFrames, "causeFrames"); Objects.requireNonNull(wrapperFrames, "wrapperFrames"); 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. *

* The use of this technique may be controversial, but exceedingly useful to * library developers. *

*
     *  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
     *      }
     *  }
     * 
*

* This is an alternative to the more conservative approach of wrapping the * checked exception in a RuntimeException: *

*
     *  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
     *      }
     *  }
     * 
*

* 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. *

* * @param throwable * The throwable to rethrow. * @param 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 rethrow(final Throwable throwable) { // claim that the typeErasure invocation throws a RuntimeException return ExceptionUtils.eraseType(throwable); } /** * Streams causes of a Throwable. *

* A throwable without cause will return a stream containing one element - the input throwable. A throwable with one cause * will return a stream containing two elements. - the input throwable and the cause throwable. A {@code null} throwable * will return a stream of count zero. *

* *

* 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. *

* * @param throwable The Throwable to traverse * @return A new Stream of Throwable causes. * @since 3.13.0 */ public static Stream stream(final Throwable throwable) { // No point building a custom Iterable as it would keep track of visited elements to avoid infinite loops return getThrowableList(throwable).stream(); } /** * Worker method for the {@code throwableOfType} methods. * * @param 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 throwableOf(final Throwable throwable, final Class 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 {@link 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. * *

A {@code null} throwable returns {@code null}. * A {@code null} type returns {@code null}. * No match in the chain returns {@code null}.

* * @param 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 throwableOfThrowable(final Throwable throwable, final Class clazz) { return throwableOf(throwable, clazz, 0, false); } /** * Returns the first {@link 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. * *

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}.

* * @param 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 throwableOfThrowable(final Throwable throwable, final Class clazz, final int fromIndex) { return throwableOf(throwable, clazz, fromIndex, false); } /** * Returns the throwable of the first {@link 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. * *

A {@code null} throwable returns {@code null}. * A {@code null} type returns {@code null}. * No match in the chain returns {@code null}.

* * @param 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 throwableOfType(final Throwable throwable, final Class type) { return throwableOf(throwable, type, 0, true); } /** * Returns the first {@link 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. * *

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}.

* * @param 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 throwableOfType(final Throwable throwable, final Class type, final int fromIndex) { return throwableOf(throwable, type, fromIndex, true); } /** * Tests whether the cause of the specified {@link Throwable} * should be thrown and does it if necessary. * * @param The Throwable type. * @param throwable the throwable to test and throw or return. * @return the given throwable. * @since 3.13.0 */ public static T throwUnchecked(final T throwable) { if (throwable instanceof RuntimeException) { throw (RuntimeException) throwable; } if (throwable instanceof Error) { throw (Error) throwable; } return throwable; } /** * 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. *

* 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. *

* * @param throwable * The throwable to rethrow. * @param 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 wrapAndThrow(final Throwable throwable) { throw new UndeclaredThrowableException(throwUnchecked(throwable)); } /** * Public constructor allows an instance of {@link ExceptionUtils} to be created, although that is not * normally necessary. * * @deprecated Will be private in 3.0. */ @Deprecated public ExceptionUtils() { } }




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