org.apache.commons.lang3.exception
Class ContextedException

java.lang.Object
  java.lang.Throwable
      java.lang.Exception
          org.apache.commons.lang3.exception.ContextedException

All Implemented Interfaces:

Serializable, ExceptionContext

public class ContextedException
extends Exception
implements ExceptionContext

An exception that provides an easy and safe way to add contextual information.

An exception trace itself is often insufficient to provide rapid diagnosis of the issue. Frequently what is needed is a select few pieces of local contextual data. Providing this data is tricky however, due to concerns over formatting and nulls.

The contexted exception approach allows the exception to be created together with a map of context values. This additional information is automatically included in the message and printed stack trace.

An unchecked version of this exception is provided by ContextedRuntimeException.

To use this class write code as follows:

   try {
     ...
   } catch (Exception e) {
     throw new ContextedException("Error posting account transaction", e)
          .addValue("accountNumber", accountNumber)
          .addValue("amountPosted", amountPosted)
          .addValue("previousBalance", previousBalance)
   }
 }
 

The output in a printStacktrace() (which often is written to a log) would look something like the following:

 org.apache.commons.lang3.exception.ContextedException: java.lang.Exception: Error posting account transaction
  Exception Context:
  [accountNumber=null]
  [amountPosted=100.00]
  [previousBalance=-2.17]

  ---------------------------------
  at org.apache.commons.lang3.exception.ContextedExceptionTest.testAddValue(ContextedExceptionTest.java:88)
  ..... (rest of trace)
 

Since:

3.0

Author:

Apache Software Foundation, D. Ashmore

See Also:

ContextedRuntimeException, Serialized Form

Constructor Summary

ContextedException()
Instantiates ContextedException without message or cause.

ContextedException(String message)
Instantiates ContextedException with message, but without cause.

ContextedException(String message, Throwable cause)
Instantiates ContextedException with cause and message.

ContextedException(String message, Throwable cause, ExceptionContext context)
Instantiates ContextedException with cause, message, and ExceptionContext.

ContextedException(Throwable cause)
Instantiates ContextedException with cause, but without message.

Method Summary

ContextedException	addValue(String label, Object value) Adds information helpful to a developer in diagnosing and correcting the problem.
String	getFormattedExceptionMessage(String baseMessage) Implementors provide the given base message with context label/value item information appended.
Set<String>	getLabelSet() Retrieves the labels defined in the contextual data.
String	getMessage() Provides the message explaining the exception, including the contextual data.
Object	getValue(String label) Retrieves a contextual data value associated with the label.
ContextedException	replaceValue(String label, Object value) Replaces information helpful to a developer in diagnosing and correcting the problem.

Methods inherited from class java.lang.Throwable

fillInStackTrace, getCause, getLocalizedMessage, getStackTrace, initCause, printStackTrace, printStackTrace, printStackTrace, setStackTrace, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

ContextedException

public ContextedException()

Instantiates ContextedException without message or cause.

The context information is stored using a default implementation.

ContextedException

public ContextedException(String message)

Instantiates ContextedException with message, but without cause.

The context information is stored using a default implementation.

Parameters:

message - the exception message, may be null

ContextedException

public ContextedException(Throwable cause)

Instantiates ContextedException with cause, but without message.

The context information is stored using a default implementation.

Parameters:

cause - the underlying cause of the exception, may be null

ContextedException

public ContextedException(String message,
                          Throwable cause)

Instantiates ContextedException with cause and message.

The context information is stored using a default implementation.

Parameters:

message - the exception message, may be null

cause - the underlying cause of the exception, may be null

ContextedException

public ContextedException(String message,
                          Throwable cause,
                          ExceptionContext context)

Instantiates ContextedException with cause, message, and ExceptionContext.

Parameters:

message - the exception message, may be null

cause - the underlying cause of the exception, may be null

context - the context used to store the additional information, null uses default implementation

Method Detail

addValue

public ContextedException addValue(String label,
                                   Object value)

Adds information helpful to a developer in diagnosing and correcting the problem. For the information to be meaningful, the value passed should have a reasonable toString() implementation. If the added label is already available, the label is appended with an index.

Note: This exception is only serializable if the object added is serializable.

Specified by:

addValue in interface ExceptionContext

Parameters:

label - a textual label associated with information, null not recommended

value - information needed to understand exception, may be null

Returns:

this, for method chaining

replaceValue

public ContextedException replaceValue(String label,
                                       Object value)

Replaces information helpful to a developer in diagnosing and correcting the problem. For the information to be meaningful, the value passed should have a reasonable toString() implementation. If the replaced label does not yet exist, it is simply added.

Note: This exception is only serializable if the object added is serializable.

Specified by:

replaceValue in interface ExceptionContext

Parameters:

label - a textual label associated with information, null not recommended

value - information needed to understand exception, may be null

Returns:

this, for method chaining

getValue

public Object getValue(String label)

Retrieves a contextual data value associated with the label.

Specified by:

getValue in interface ExceptionContext

Parameters:

label - the label to get the contextual value for, may be null

Returns:

the contextual value associated with the label, may be null

getLabelSet

public Set<String> getLabelSet()

Retrieves the labels defined in the contextual data.

Specified by:

getLabelSet in interface ExceptionContext

Returns:

the set of labels, never null

getMessage

public String getMessage()

Provides the message explaining the exception, including the contextual data.

Overrides:

getMessage in class Throwable

Returns:

the message, never null

See Also:

Throwable.getMessage()

getFormattedExceptionMessage

public String getFormattedExceptionMessage(String baseMessage)

Implementors provide the given base message with context label/value item information appended.

Specified by:

getFormattedExceptionMessage in interface ExceptionContext

Parameters:

baseMessage - the base exception message without context information appended

Returns:

the exception message with context information appended, never null