org.apache.commons.lang.exception
Class NestableException

java.lang.Object
  extended by java.lang.Throwable
      extended by java.lang.Exception
          extended by 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 491651 2007-01-01 22:01:32Z ggregory $
Author:
Rafal Krzewski, Daniel 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.


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