ContextedException

public class org.apache.commons.lang3.exception.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)

See also:

ContextedRuntimeException

Since:

3.0

Constructors

ContextedException()	Instantiates ContextedException without message or cause.
ContextedException(String)	Instantiates ContextedException with message, but without cause.
ContextedException(String, Throwable)	Instantiates ContextedException with cause and message.
ContextedException(String, Throwable, ExceptionContext)	Instantiates ContextedException with cause, message, and ExceptionContext.
ContextedException(Throwable)	Instantiates ContextedException with cause, but without message.

public ContextedException()

Instantiates ContextedException without message or cause.

The context information is stored using a default implementation.

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

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

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

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

Methods

addContextValue(String, Object)	Adds information helpful to a developer in diagnosing and correcting the problem.
getContextEntries()	Gets the full list of label-value pairs defined in the contextual data.
getContextLabels()	Gets the full set of labels defined in the contextual data.
getContextValues(String)	Gets all the contextual data values associated with the label.
getFirstContextValue(String)	Gets the first available contextual data value associated with the label.
getFormattedExceptionMessage(String)	Gets the contextualized error message based on a base message.
getMessage()	Gets the message explaining the exception, including the contextual data.
getRawMessage()	Gets the message explaining the exception without the contextual data.
setContextValue(String, Object)	Sets information helpful to a developer in diagnosing and correcting the problem.

@Override 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.

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

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

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

Returns:

The list of pairs, not null

@Override public Set<String> getContextLabels()

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

Returns:

The set of labels, not null

@Override public List<Object> getContextValues(String label)

Gets all the contextual data values associated with the label.

Parameters:

label – The label to get the contextual values for, may be null

Returns:

The contextual values associated with the label, never null

@Override public Object getFirstContextValue(String label)

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

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

@Override 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.

Parameters:

baseMessage – The base exception message without context information appended

Returns:

The exception message with context information appended, not null

@Override public String getMessage()

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

See also:

Throwable#getMessage()

Returns:

The message, never null

public String getRawMessage()

Gets the message explaining the exception without the contextual data.

See also:

Throwable#getMessage()

Returns:

The message

Since:

3.0.1

@Override 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.

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