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 list of context label-value pairs. 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)
          .addContextValue("Account Number", accountNumber)
          .addContextValue("Amount Posted", amountPosted)
          .addContextValue("Previous Balance", previousBalance)
   }
 }
 

or improve diagnose data at a higher level:

   try {
     ...
   } catch (ContextedException e) {
     throw e.setContextValue("Transaction Id", transactionId);
   } catch (Exception e) {
     if (e instanceof ExceptionContext) {
       e.setContextValue("Transaction Id", transactionId);
     }
     throw e;
   }
 }
 

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:
  [1:Account Number=null]
  [2:Amount Posted=100.00]
  [3:Previous Balance=-2.17]
  [4:Transaction Id=94ef1d15-d443-46c4-822b-637f26244899]

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

Since:

3.0

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	addContextValue(String label, Object value) Adds information helpful to a developer in diagnosing and correcting the problem.
List<Pair<String,Object>>	getContextEntries() Retrieves the full list of label-value pairs defined in the contextual data.
Set<String>	getContextLabels() Retrieves the full set of labels defined in the contextual data.
List<Object>	getContextValues(String label) Retrieves all the contextual data values associated with the label.
Object	getFirstContextValue(String label) Retrieves the first available contextual data value associated with the label.
String	getFormattedExceptionMessage(String baseMessage) Gets the contextualized error message based on a base message.
String	getMessage() Provides the message explaining the exception, including the contextual data.
ContextedException	setContextValue(String label, Object value) Sets 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

addContextValue

public ContextedException addContextValue(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. Different values can be added with the same label multiple times.

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

Specified by:

addContextValue 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, not null

setContextValue

public ContextedException setContextValue(String label,
                                          Object value)

Sets 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. Any existing values with the same labels are removed before the new one is added.

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

Specified by:

setContextValue 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, not null

getContextValues

public List<Object> getContextValues(String label)

Retrieves all the contextual data values associated with the label.

Specified by:

getContextValues in interface ExceptionContext

Parameters:

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

Returns:

the contextual values associated with the label, never null

getFirstContextValue

public Object getFirstContextValue(String label)

Retrieves the first available contextual data value associated with the label.

Specified by:

getFirstContextValue in interface ExceptionContext

Parameters:

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

Returns:

the first contextual value associated with the label, may be null

getContextEntries

public List<Pair<String,Object>> getContextEntries()

Retrieves the full list of label-value pairs defined in the contextual data.

Specified by:

getContextEntries in interface ExceptionContext

Returns:

the list of pairs, not null

getContextLabels

public Set<String> getContextLabels()

Retrieves the full set of labels defined in the contextual data.

Specified by:

getContextLabels in interface ExceptionContext

Returns:

the set of labels, not 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)

Gets the contextualized error message based on a base message. This will add the context label-value pairs to the message.

Specified by:

getFormattedExceptionMessage in interface ExceptionContext

Parameters:

baseMessage - the base exception message without context information appended

Returns:

the exception message with context information appended, not null