Package org.codehaus.plexus.util

Class ExceptionUtils

java.lang.Object

org.codehaus.plexus.util.ExceptionUtils

public class ExceptionUtils
extends Object

ExceptionUtils provides utilities for manipulating Throwable objects.

Since:

1.0

Author:

Daniel Rall, Dmitri Plotnikov, Stephen Colebourne

Field Summary

Fields

Modifier and Type	Field	Description
protected static String[]	CAUSE_METHOD_NAMES	The names of methods commonly used to access a wrapped exception.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	ExceptionUtils()	Constructs a new ExceptionUtils.

Method Summary

Modifier and Type	Method	Description
static void	addCauseMethodName(String methodName)	Adds to the list of method names used in the search for Throwable objects.
static Throwable	getCause(Throwable throwable)	Introspects the specified Throwable to obtain the cause.
static Throwable	getCause(Throwable throwable, String[] methodNames)	Introspects the specified Throwable to obtain the cause using a supplied array of method names.
static String	getFullStackTrace(Throwable t)	A way to get the entire nested stack-trace of an throwable.
static Throwable	getRootCause(Throwable throwable)	Walks through the exception chain to the last element -- the "root" of the tree -- using getCause(Throwable), and returns that exception.
static String[]	getRootCauseStackTrace(Throwable t)	Creates a compact stack trace for the root cause of the supplied throwable.
static String[]	getStackFrames(Throwable t)	Captures the stack trace associated with the specified Throwable object, decomposing it into a list of stack frames.
static String	getStackTrace(Throwable t)	A convenient way of extracting the stack trace from an exception.
static int	getThrowableCount(Throwable throwable)	Returns the number of Throwable objects in the exception chain.
static Throwable[]	getThrowables(Throwable throwable)	Returns the list of Throwable objects in the exception chain.
static int	indexOfThrowable(Throwable throwable, Class type)	Delegates to indexOfThrowable(Throwable, Class, int), starting the search at the beginning of the exception chain.
static int	indexOfThrowable(Throwable throwable, Class type, int fromIndex)	Returns the (zero based) index, of the first Throwable that matches the specified type in the exception chain of Throwable objects with an index greater than or equal to the specified index, or -1 if the type is not found.
static boolean	isNestedThrowable(Throwable throwable)	Whether an Throwable is considered nested or not.
static void	printRootCauseStackTrace(Throwable t)	Equivalent to printRootCauseStackTrace(t, System.err)
static void	printRootCauseStackTrace(Throwable t, PrintStream stream)	Prints a compact stack trace for the root cause of a throwable.
static void	printRootCauseStackTrace(Throwable t, PrintWriter writer)	Same as printRootCauseStackTrace(t, stream), except it takes a PrintWriter as an argument.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

CAUSE_METHOD_NAMES

protected static String[] CAUSE_METHOD_NAMES

The names of methods commonly used to access a wrapped exception.

Constructor Details

ExceptionUtils

protected ExceptionUtils()

Constructs a new ExceptionUtils. Protected to discourage instantiation.

Method Details

addCauseMethodName

public static void addCauseMethodName(String methodName)

Adds to the list of method names used in the search for Throwable objects.

Parameters:

methodName - the methodName to add to the list, null and empty strings are ignored

getCause

public static Throwable getCause(Throwable throwable)

Introspects the specified Throwable to obtain the cause.

The method searches for methods with specific names that return a Throwable object. This will pick up most wrapping exceptions, including those from JDK 1.4, and The method names can be added to using addCauseMethodName(String). The default list searched for are:

• getCause()
• getNextException()
• getTargetException()
• getException()
• getSourceException()
• getRootCause()
• getCausedByException()
• getNested()

In the absence of any such method, the object is inspected for a detail field assignable to a Throwable.

If none of the above is found, returns null.

Parameters:

throwable - The exception to introspect for a cause.

Returns:

The cause of the Throwable.

Throws:

NullPointerException - if the throwable is null

getCause

public static Throwable getCause(Throwable throwable,
 String[] methodNames)

Introspects the specified Throwable to obtain the cause using a supplied array of method names.

Parameters:

throwable - The exception to introspect for a cause.

methodNames - the methods names to match

Returns:

The cause of the Throwable.

Throws:

NullPointerException - if the method names array is null or contains null

NullPointerException - if the throwable is null

getRootCause

public static Throwable getRootCause(Throwable throwable)

Walks through the exception chain to the last element -- the "root" of the tree -- using getCause(Throwable), and returns that exception.

Parameters:

throwable - the throwable to get the root cause for

Returns:

The root cause of the Throwable.

getThrowableCount

public static int getThrowableCount(Throwable throwable)

Returns the number of Throwable objects in the exception chain.

Parameters:

throwable - the exception to inspect

Returns:

The throwable count.

getThrowables

public static Throwable[] getThrowables(Throwable throwable)

Returns the list of Throwable objects in the exception chain.

Parameters:

throwable - the exception to inspect

Returns:

The list of Throwable objects.

indexOfThrowable

public static int indexOfThrowable(Throwable throwable,
 Class type)

Delegates to indexOfThrowable(Throwable, Class, int), starting the search at the beginning of the exception chain.

Parameters:

throwable - the exception to inspect

type - Class to look for

Returns:

index of the stack matching the type

See Also:

• indexOfThrowable(Throwable, Class, int)

indexOfThrowable

public static int indexOfThrowable(Throwable throwable,
 Class type,
 int fromIndex)

Returns the (zero based) index, of the first Throwable that matches the specified type in the exception chain of Throwable objects with an index greater than or equal to the specified index, or -1 if the type is not found.

Parameters:

throwable - the exception to inspect

type - Class to look for

fromIndex - the (zero based) index of the starting position in the chain to be searched

Returns:

the first occurrence of the type in the chain, or -1 if the type is not found

Throws:

IndexOutOfBoundsException - If the fromIndex argument is negative or not less than the count of Throwables in the chain.

printRootCauseStackTrace

public static void printRootCauseStackTrace(Throwable t,
 PrintStream stream)

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 method is equivalent to t.printStackTrace() for throwables that don't have nested causes.

Parameters:

t - the exception

stream - the stream

printRootCauseStackTrace

public static void printRootCauseStackTrace(Throwable t)

Equivalent to printRootCauseStackTrace(t, System.err)

Parameters:

t - the exception

printRootCauseStackTrace

public static void printRootCauseStackTrace(Throwable t,
 PrintWriter writer)

Same as printRootCauseStackTrace(t, stream), except it takes a PrintWriter as an argument.

Parameters:

t - the cause

writer - the writer

getRootCauseStackTrace

public static String[] getRootCauseStackTrace(Throwable t)

Creates a compact stack trace for the root cause of the supplied throwable. See printRootCauseStackTrace(Throwable t, PrintStream s)

Parameters:

t - the cause

Returns:

the Stack

getStackTrace

public static String getStackTrace(Throwable t)

A convenient way of extracting the stack trace from an exception.

Parameters:

t - The Throwable.

Returns:

The stack trace as generated by the exception's printStackTrace(PrintWriter) method.

getFullStackTrace

public static String getFullStackTrace(Throwable t)

A way to get the entire nested stack-trace of an throwable.

Parameters:

t - The Throwable.

Returns:

The nested stack trace, with the root cause first.

isNestedThrowable

public static boolean isNestedThrowable(Throwable throwable)

Whether an Throwable is considered nested or not.

Parameters:

throwable - The Throwable.

Returns:

boolean true/false

getStackFrames

public static String[] getStackFrames(Throwable t)

Captures the stack trace associated with the specified Throwable object, decomposing it into a list of stack frames.

Parameters:

t - The Throwable.

Returns:

An array of strings describing each stack frame.