Javadoc changes, with better description of trace methods
git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/lang/trunk@366617 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Stephen Colebourne
parent
de9d22e2ba
commit
dcb7dded14
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@ -1,5 +1,5 @@
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/*
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* Copyright 2002-2005 The Apache Software Foundation.
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* Copyright 2002-2006 The Apache Software Foundation.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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@ -29,13 +29,13 @@
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import java.util.StringTokenizer;
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import org.apache.commons.lang.ArrayUtils;
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import org.apache.commons.lang.NullArgumentException;
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import org.apache.commons.lang.StringUtils;
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import org.apache.commons.lang.SystemUtils;
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import org.apache.commons.lang.NullArgumentException;
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/**
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* <p>Provides utilities for manipulating and examining
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<code>Throwable</code> objects.</p>
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* <code>Throwable</code> objects.</p>
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*
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* @author <a href="mailto:dlr@finemaltcoding.com">Daniel Rall</a>
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* @author Dmitri Plotnikov
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@ -74,16 +74,12 @@ public class ExceptionUtils {
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};
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/**
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* <p>
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* The Method object for Java 1.4 getCause.
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* </p>
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* <p>The Method object for Java 1.4 getCause.</p>
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*/
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private static final Method THROWABLE_CAUSE_METHOD;
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/**
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* <p>
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* The Method object for Java 1.4 initCause.
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* </p>
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* <p>The Method object for Java 1.4 initCause.</p>
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*/
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private static final Method THROWABLE_INITCAUSE_METHOD;
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@ -149,16 +145,12 @@ public static void removeCauseMethodName(String methodName) {
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}
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/**
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* <p>
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* Sets the cause of a <code>Throwable</code> using introspection, allowing source code compatibility between
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* pre-1.4 and post-1.4 Java releases.
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* </p>
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*
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* <p>
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* The typical use of this method is inside a constructor as in the following example:
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* </p>
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*
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* <p>
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* <p>Sets the cause of a <code>Throwable</code> using introspection, allowing
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* source code compatibility between pre-1.4 and post-1.4 Java releases.</p>
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*
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* <p>The typical use of this method is inside a constructor as in
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* the following example:</p>
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*
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* <pre>
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* import org.apache.commons.lang.exception.ExceptionUtils;
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*
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@ -167,20 +159,16 @@ public static void removeCauseMethodName(String methodName) {
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* public MyException(String msg) {
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* super(msg);
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* }
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*
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*
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* public MyException(String msg, Throwable cause) {
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* super(msg);
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* ExceptionUtils.setCause(this, cause);
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* }
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*
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* }
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* }
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* </pre>
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* </p>
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*
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* @param target
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* the target <code>Throwable</code>
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* @param cause
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* the <code>Throwable</code> to set in the target
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*
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* @param target the target <code>Throwable</code>
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* @param cause the <code>Throwable</code> to set in the target
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* @return a <code>true</code> if the target has been modified
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* @since 2.2
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*/
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@ -225,6 +213,7 @@ private static String[] toArray(List list) {
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/**
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* Returns {@link #CAUSE_METHOD_NAMES} as a List.
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*
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* @return {@link #CAUSE_METHOD_NAMES} as a List.
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*/
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private static ArrayList getCauseMethodNameList() {
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@ -246,7 +235,7 @@ public static boolean isCauseMethodName(String methodName) {
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/**
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* <p>Introspects the <code>Throwable</code> to obtain the cause.</p>
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*
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*
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* <p>The method searches for methods with specific names that return a
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* <code>Throwable</code> object. This will pick up most wrapping exceptions,
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* including those from JDK 1.4, and
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@ -267,7 +256,7 @@ public static boolean isCauseMethodName(String methodName) {
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*
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* <p>In the absence of any such method, the object is inspected for a
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* <code>detail</code> field assignable to a <code>Throwable</code>.</p>
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*
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*
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* <p>If none of the above is found, returns <code>null</code>.</p>
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*
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* @param throwable the throwable to introspect for a cause, may be null
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@ -281,13 +270,13 @@ public static Throwable getCause(Throwable throwable) {
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/**
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* <p>Introspects the <code>Throwable</code> to obtain the cause.</p>
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*
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*
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* <ol>
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* <li>Try known exception types.</li>
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* <li>Try the supplied array of method names.</li>
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* <li>Try the field 'detail'.</li>
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* </ol>
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*
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*
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* <p>A <code>null</code> set of method names means use the default set.
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* A <code>null</code> in the set of method names will be ignored.</p>
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*
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@ -325,7 +314,7 @@ public static Throwable getCause(Throwable throwable, String[] methodNames) {
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/**
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* <p>Introspects the <code>Throwable</code> to obtain the root cause.</p>
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*
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*
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* <p>This method walks through the exception chain to the last element,
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* "root" of the tree, using {@link #getCause(Throwable)}, and
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* returns that exception.</p>
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@ -369,7 +358,7 @@ private static Throwable getCauseUsingWellKnownTypes(Throwable throwable) {
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/**
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* <p>Finds a <code>Throwable</code> by method name.</p>
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*
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*
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* @param throwable the exception to examine
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* @param methodName the name of the method to find and invoke
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* @return the wrapped exception, or <code>null</code> if not found
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@ -400,7 +389,7 @@ private static Throwable getCauseUsingMethodName(Throwable throwable, String met
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/**
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* <p>Finds a <code>Throwable</code> by field name.</p>
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*
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*
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* @param throwable the exception to examine
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* @param fieldName the name of the attribute to examine
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* @return the wrapped exception, or <code>null</code> if not found
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@ -430,9 +419,9 @@ private static Throwable getCauseUsingFieldName(Throwable throwable, String fiel
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//-----------------------------------------------------------------------
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/**
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* <p>Checks if the Throwable class has a <code>getCause</code> method.</p>
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*
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*
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* <p>This is true for JDK 1.4 and above.</p>
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*
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*
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* @return true if Throwable is nestable
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* @since 2.0
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*/
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@ -442,7 +431,7 @@ public static boolean isThrowableNested() {
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/**
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* <p>Checks whether this <code>Throwable</code> class can store a cause.</p>
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*
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*
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* <p>This method does <b>not</b> check whether it actually does store a cause.<p>
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*
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* @param throwable the <code>Throwable</code> to examine, may be null
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@ -496,11 +485,11 @@ public static boolean isNestedThrowable(Throwable throwable) {
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/**
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* <p>Counts the number of <code>Throwable</code> objects in the
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* exception chain.</p>
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*
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*
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* <p>A throwable without cause will return <code>1</code>.
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* A throwable with one cause will return <code>2</code> and so on.
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* A <code>null</code> throwable will return <code>0</code>.</p>
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*
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*
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* @param throwable the throwable to inspect, may be null
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* @return the count of throwables, zero if null input
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*/
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@ -516,7 +505,7 @@ public static int getThrowableCount(Throwable throwable) {
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/**
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* <p>Returns the list of <code>Throwable</code> objects in the
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* exception chain.</p>
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*
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*
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* <p>A throwable without cause will return an array containing
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* one element - the input throwable.
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* A throwable with one cause will return an array containing
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@ -541,7 +530,7 @@ public static Throwable[] getThrowables(Throwable throwable) {
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* that matches the specified class (exactly) in the exception chain.
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* Subclasses of the specified class do not match - see
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* {@link #indexOfType(Throwable, Class)} for the opposite.</p>
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*
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*
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* <p>A <code>null</code> throwable returns <code>-1</code>.
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* A <code>null</code> type returns <code>-1</code>.
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* No match in the chain returns <code>-1</code>.</p>
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@ -560,7 +549,7 @@ public static int indexOfThrowable(Throwable throwable, Class clazz) {
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* a specified index.
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* Subclasses of the specified class do not match - see
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* {@link #indexOfType(Throwable, Class, int)} for the opposite.</p>
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*
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*
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* <p>A <code>null</code> throwable returns <code>-1</code>.
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* A <code>null</code> type returns <code>-1</code>.
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* No match in the chain returns <code>-1</code>.
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@ -583,7 +572,7 @@ public static int indexOfThrowable(Throwable throwable, Class clazz, int fromInd
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* that matches the specified class or subclass in the exception chain.
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* Subclasses of the specified class do match - see
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* {@link #indexOfThrowable(Throwable, Class)} for the opposite.</p>
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*
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*
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* <p>A <code>null</code> throwable returns <code>-1</code>.
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* A <code>null</code> type returns <code>-1</code>.
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* No match in the chain returns <code>-1</code>.</p>
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@ -603,7 +592,7 @@ public static int indexOfType(Throwable throwable, Class type) {
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* a specified index.
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* Subclasses of the specified class do match - see
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* {@link #indexOfThrowable(Throwable, Class)} for the opposite.</p>
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*
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*
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* <p>A <code>null</code> throwable returns <code>-1</code>.
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* A <code>null</code> type returns <code>-1</code>.
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* No match in the chain returns <code>-1</code>.
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@ -623,7 +612,7 @@ public static int indexOfType(Throwable throwable, Class type, int fromIndex) {
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/**
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* <p>Worker method for the <code>indexOfType</code> methods.</p>
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*
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*
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* @param throwable the throwable to inspect, may be null
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* @param type the type to search for, subclasses match, null returns -1
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* @param fromIndex the (zero based) index of the starting position,
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@ -663,15 +652,18 @@ private static int indexOf(Throwable throwable, Class type, int fromIndex, boole
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/**
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* <p>Prints a compact stack trace for the root cause of a throwable
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* to <code>System.err</code>.</p>
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*
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*
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* <p>The compact stack trace starts with the root cause and prints
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* stack frames up to the place where it was caught and wrapped.
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* Then it prints the wrapped exception and continues with stack frames
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* until the wrapper exception is caught and wrapped again, etc.</p>
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*
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* <p>The output of this method is consistent across JDK versions.
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* Note that this is the opposite order to the JDK1.4 display.</p>
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*
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* <p>The method is equivalent to <code>printStackTrace</code> for throwables
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* that don't have nested causes.</p>
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*
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*
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* @param throwable the throwable to output
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* @since 2.0
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*/
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@ -687,9 +679,12 @@ public static void printRootCauseStackTrace(Throwable throwable) {
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* Then it prints the wrapped exception and continues with stack frames
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* until the wrapper exception is caught and wrapped again, etc.</p>
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*
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* <p>The output of this method is consistent across JDK versions.
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* Note that this is the opposite order to the JDK1.4 display.</p>
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*
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* <p>The method is equivalent to <code>printStackTrace</code> for throwables
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* that don't have nested causes.</p>
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*
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*
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* @param throwable the throwable to output, may be null
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* @param stream the stream to output to, may not be null
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* @throws IllegalArgumentException if the stream is <code>null</code>
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@ -717,9 +712,12 @@ public static void printRootCauseStackTrace(Throwable throwable, PrintStream str
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* Then it prints the wrapped exception and continues with stack frames
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* until the wrapper exception is caught and wrapped again, etc.</p>
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*
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* <p>The output of this method is consistent across JDK versions.
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* Note that this is the opposite order to the JDK1.4 display.</p>
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*
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* <p>The method is equivalent to <code>printStackTrace</code> for throwables
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* that don't have nested causes.</p>
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*
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*
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* @param throwable the throwable to output, may be null
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* @param writer the writer to output to, may not be null
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* @throws IllegalArgumentException if the writer is <code>null</code>
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@ -743,7 +741,12 @@ public static void printRootCauseStackTrace(Throwable throwable, PrintWriter wri
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/**
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* <p>Creates a compact stack trace for the root cause of the supplied
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* <code>Throwable</code>.</p>
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*
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*
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* <p>The output of this method is consistent across JDK versions.
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* It consists of the root exception followed by each of its wrapping
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* exceptions separated by '[wrapped]'. Note that this is the opposite
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* order to the JDK1.4 display.</p>
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*
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* @param throwable the throwable to examine, may be null
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* @return an array of stack trace frames, never null
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* @since 2.0
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@ -776,7 +779,7 @@ public static String[] getRootCauseStackTrace(Throwable throwable) {
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/**
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* <p>Removes common frames from the cause trace given the two stack traces.</p>
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*
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*
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* @param causeFrames stack trace of a cause throwable
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* @param wrapperFrames stack trace of a wrapper throwable
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* @throws IllegalArgumentException if either argument is null
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@ -805,6 +808,11 @@ public static void removeCommonFrames(List causeFrames, List wrapperFrames) {
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/**
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* <p>Gets the stack trace from a Throwable as a String.</p>
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*
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* <p>The result of this method vary by JDK version as this method
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* uses {@link Throwable#printStackTrace(java.io.PrintWriter)}.
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* On JDK1.3 and earlier, the cause exception will not be shown
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* unless the specified throwable alters printStackTrace.</p>
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*
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* @param throwable the <code>Throwable</code> to be examined
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* @return the stack trace as generated by the exception's
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* <code>printStackTrace(PrintWriter)</code> method
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@ -819,6 +827,9 @@ public static String getStackTrace(Throwable throwable) {
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/**
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* <p>A way to get the entire nested stack-trace of an throwable.</p>
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*
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* <p>The result of this method is highly dependent on the JDK version
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* and whether the exceptions override printStackTrace or not.</p>
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*
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* @param throwable the <code>Throwable</code> to be examined
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* @return the nested stack trace, with the root cause first
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* @since 2.0
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@ -842,6 +853,11 @@ public static String getFullStackTrace(Throwable throwable) {
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* <code>Throwable</code> object, decomposing it into a list of
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* stack frames.</p>
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*
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* <p>The result of this method vary by JDK version as this method
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* uses {@link Throwable#printStackTrace(java.io.PrintWriter)}.
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* On JDK1.3 and earlier, the cause exception will not be shown
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* unless the specified throwable alters printStackTrace.</p>
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*
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* @param throwable the <code>Throwable</code> to examine, may be null
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* @return an array of strings describing each stack frame, never null
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*/
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@ -853,21 +869,16 @@ public static String[] getStackFrames(Throwable throwable) {
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}
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/**
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* <p>
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* Returns an array where each element is a line from the argument.
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* </p>
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* <p>
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* The end of line is determined by the value of {@link SystemUtils#LINE_SEPARATOR}.
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* </p>
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*
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* <p>
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* Functionality shared between the <code>getStackFrames(Throwable)</code> methods of this and the
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* {@link org.apache.commons.lang.exception.NestableDelegate} classes.
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* </p>
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*
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* @param stackTrace
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* A stack trace String.
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* @return an array where each element is a line from the argument.
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* <p>Returns an array where each element is a line from the argument.</p>
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*
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* <p>The end of line is determined by the value of {@link SystemUtils#LINE_SEPARATOR}.</p>
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*
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* <p>Functionality shared between the
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* <code>getStackFrames(Throwable)</code> methods of this and the
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* {@link org.apache.commons.lang.exception.NestableDelegate} classes.</p>
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*
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* @param stackTrace a stack trace String
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* @return an array where each element is a line from the argument
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*/
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static String[] getStackFrames(String stackTrace) {
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String linebreak = SystemUtils.LINE_SEPARATOR;
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@ -881,7 +892,8 @@ static String[] getStackFrames(String stackTrace) {
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/**
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* <p>Produces a <code>List</code> of stack frames - the message
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* is not included.</p>
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* is not included. Only the trace of the specified exception is
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* returned, any caused by trace is stripped.</p>
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*
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* <p>This works in most cases - it will only fail if the exception
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* message contains a line that starts with:
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@ -909,5 +921,5 @@ static List getStackFrameList(Throwable t) {
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}
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return list;
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}
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}
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