org.apache.commons.lang.exception
Class NestableException

java.lang.Object
  java.lang.Throwable
      java.lang.Exception
          org.apache.commons.lang.exception.NestableException

All Implemented Interfaces:

Serializable, Nestable

public class NestableException
extends Exception
implements Nestable

The base class of all exceptions which can contain other exceptions. It is intended to ease the debugging by carrying on the information about the exception which was caught and provoked throwing the current exception. Catching and rethrowing may occur multiple times, and provided that all exceptions except the first one are descendants of NestedException, when the exception is finally printed out using any of the printStackTrace() methods, the stack trace will contain the information about all exceptions thrown and caught on the way.

Running the following program

  1 import org.apache.commons.lang.exception.NestableException;
  2
  3 public class Test {
  4     public static void main( String[] args ) {
  5         try {
  6             a();
  7         } catch(Exception e) {
  8             e.printStackTrace();
  9         }
 10      }
 11
 12      public static void a() throws Exception {
 13          try {
 14              b();
 15          } catch(Exception e) {
 16              throw new NestableException("foo", e);
 17          }
 18      }
 19
 20      public static void b() throws Exception {
 21          try {
 22              c();
 23          } catch(Exception e) {
 24              throw new NestableException("bar", e);
 25          }
 26      }
 27
 28      public static void c() throws Exception {
 29          throw new Exception("baz");
 30      }
 31 }
 

Yields the following stack trace:

 org.apache.commons.lang.exception.NestableException: foo
         at Test.a(Test.java:16)
         at Test.main(Test.java:6)
 Caused by: org.apache.commons.lang.exception.NestableException: bar
         at Test.b(Test.java:24)
         at Test.a(Test.java:14)
         ... 1 more
 Caused by: java.lang.Exception: baz
         at Test.c(Test.java:29)
         at Test.b(Test.java:22)
         ... 2 more
 

Since:

1.0

Version:

$Id: NestableException.java 512889 2007-02-28 18:18:20Z dlr $

Author:

Rafal Krzewski, Daniel L. Rall, Kasper Nielsen, Steven Caswell

See Also:

Serialized Form

Field Summary

protected NestableDelegate

delegate The helper instance which contains much of the code which we delegate to.

Constructor Summary

NestableException()
Constructs a new NestableException without specified detail message.

NestableException(String msg)
Constructs a new NestableException with specified detail message.

NestableException(String msg, Throwable cause)
Constructs a new NestableException with specified detail message and nested Throwable.

NestableException(Throwable cause)
Constructs a new NestableException with specified nested Throwable.

Method Summary

Throwable	getCause() Returns the reference to the exception or error that caused the exception implementing the Nestable to be thrown.
String	getMessage() Returns the detail message string of this throwable.
String	getMessage(int index) Returns the error message of the Throwable in the chain of Throwables at the specified index, numbered from 0.
String[]	getMessages() Returns the error message of this and any nested Throwables in an array of Strings, one element for each message.
Throwable	getThrowable(int index) Returns the Throwable in the chain of Throwables at the specified index, numbered from 0.
int	getThrowableCount() Returns the number of nested Throwables represented by this Nestable, including this Nestable.
Throwable[]	getThrowables() Returns this Nestable and any nested Throwables in an array of Throwables, one element for each Throwable.
int	indexOfThrowable(Class type) Returns the index, numbered from 0, of the first occurrence of the specified type, or a subclass, in the chain of Throwables.
int	indexOfThrowable(Class type, int fromIndex) Returns the index, numbered from 0, of the first Throwable that matches the specified type, or a subclass, in the chain of Throwables with an index greater than or equal to the specified index.
void	printPartialStackTrace(PrintWriter out) Prints the stack trace for this exception only--root cause not included--using the provided writer.
void	printStackTrace()
void	printStackTrace(PrintStream out) Prints the stack trace of this exception to the specified print stream.
void	printStackTrace(PrintWriter out) Prints the stack trace of this exception to the specified print writer.

Methods inherited from class java.lang.Throwable

fillInStackTrace, getLocalizedMessage, getStackTrace, initCause, setStackTrace, toString

Methods inherited from class java.lang.Object

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

Field Detail

delegate

protected NestableDelegate delegate

The helper instance which contains much of the code which we delegate to.

Constructor Detail

NestableException

public NestableException()

Constructs a new NestableException without specified detail message.

NestableException

public NestableException(String msg)

Constructs a new NestableException with specified detail message.

Parameters:

msg - The error message.

NestableException

public NestableException(Throwable cause)

Constructs a new NestableException with specified nested Throwable.

Parameters:

cause - the exception or error that caused this exception to be thrown

NestableException

public NestableException(String msg,
                         Throwable cause)

Constructs a new NestableException with specified detail message and nested Throwable.

Parameters:

msg - the error message

cause - the exception or error that caused this exception to be thrown

Method Detail

getCause

public Throwable getCause()

Returns the reference to the exception or error that caused the exception implementing the Nestable to be thrown.

Specified by:

getCause in interface Nestable

Overrides:

getCause in class Throwable

Returns:

throwable that caused the original exception

getMessage

public String getMessage()

Returns the detail message string of this throwable. If it was created with a null message, returns the following: (cause==null ? null : cause.toString()).

Specified by:

getMessage in interface Nestable

Overrides:

getMessage in class Throwable

Returns:

String message string of the throwable

getMessage

public String getMessage(int index)

Returns the error message of the Throwable in the chain of Throwables at the specified index, numbered from 0.

Specified by:

getMessage in interface Nestable

Parameters:

index - the index of the Throwable in the chain of Throwables

Returns:

the error message, or null if the Throwable at the specified index in the chain does not contain a message

getMessages

public String[] getMessages()

Returns the error message of this and any nested Throwables in an array of Strings, one element for each message. Any Throwable not containing a message is represented in the array by a null. This has the effect of cause the length of the returned array to be equal to the result of the Nestable.getThrowableCount() operation.

Specified by:

getMessages in interface Nestable

Returns:

the error messages

getThrowable

public Throwable getThrowable(int index)

Returns the Throwable in the chain of Throwables at the specified index, numbered from 0.

Specified by:

getThrowable in interface Nestable

Parameters:

index - the index, numbered from 0, of the Throwable in the chain of Throwables

Returns:

the Throwable

getThrowableCount

public int getThrowableCount()

Returns the number of nested Throwables represented by this Nestable, including this Nestable.

Specified by:

getThrowableCount in interface Nestable

Returns:

the throwable count

getThrowables

public Throwable[] getThrowables()

Returns this Nestable and any nested Throwables in an array of Throwables, one element for each Throwable.

Specified by:

getThrowables in interface Nestable

Returns:

the Throwables

indexOfThrowable

public int indexOfThrowable(Class type)

Returns the index, numbered from 0, of the first occurrence of the specified type, or a subclass, in the chain of Throwables. The method returns -1 if the specified type is not found in the chain.

NOTE: From v2.1, we have clarified the Nestable interface such that this method matches subclasses. If you want to NOT match subclasses, please use ExceptionUtils.indexOfThrowable(Throwable, Class) (which is avaiable in all versions of lang).

Specified by:

indexOfThrowable in interface Nestable

Parameters:

type - the type to find, subclasses match, null returns -1

Returns:

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

indexOfThrowable

public int indexOfThrowable(Class type,
                            int fromIndex)

Returns the index, numbered from 0, of the first Throwable that matches the specified type, or a subclass, in the chain of Throwables with an index greater than or equal to the specified index. The method returns -1 if the specified type is not found in the chain.

NOTE: From v2.1, we have clarified the Nestable interface such that this method matches subclasses. If you want to NOT match subclasses, please use ExceptionUtils.indexOfThrowable(Throwable, Class, int) (which is avaiable in all versions of lang).

Specified by:

indexOfThrowable in interface Nestable

Parameters:

type - the type to find, subclasses match, null returns -1

fromIndex - the index, numbered from 0, of the starting position in the chain to be searched

Returns:

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

printStackTrace

public void printStackTrace()

Overrides:

printStackTrace in class Throwable

printStackTrace

public void printStackTrace(PrintStream out)

Prints the stack trace of this exception to the specified print stream. Includes information from the exception, if any, which caused this exception.

Specified by:

printStackTrace in interface Nestable

Overrides:

printStackTrace in class Throwable

Parameters:

out - PrintStream to use for output.

printStackTrace

public void printStackTrace(PrintWriter out)

Prints the stack trace of this exception to the specified print writer. Includes information from the exception, if any, which caused this exception.

Specified by:

printStackTrace in interface Nestable

Overrides:

printStackTrace in class Throwable

Parameters:

out - PrintWriter to use for output.

printPartialStackTrace

public final void printPartialStackTrace(PrintWriter out)

Prints the stack trace for this exception only--root cause not included--using the provided writer. Used by NestableDelegate to write individual stack traces to a buffer. The implementation of this method should call super.printStackTrace(out); in most cases.

Specified by:

printPartialStackTrace in interface Nestable

Parameters:

out - The writer to use.