org.apache.commons.io
Class TaggedIOException

java.lang.Object
  extended by java.lang.Throwable
      extended by java.lang.Exception
          extended by java.io.IOException
              extended by org.apache.commons.io.IOExceptionWithCause
                  extended by org.apache.commons.io.TaggedIOException
All Implemented Interfaces:
Serializable

public class TaggedIOException
extends IOExceptionWithCause

An IOException decorator that adds a serializable tag to the wrapped exception. Both the tag and the original exception can be used to determine further processing when this exception is caught.

Since:
2.0
See Also:
Serialized Form

Constructor Summary
TaggedIOException(IOException original, Serializable tag)
          Creates a tagged wrapper for the given exception.
 
Method Summary
 IOException getCause()
          Returns the wrapped exception.
 Serializable getTag()
          Returns the serializable tag object.
static boolean isTaggedWith(Throwable throwable, Object tag)
          Checks whether the given throwable is tagged with the given tag.
static void throwCauseIfTaggedWith(Throwable throwable, Object tag)
          Throws the original IOException if the given throwable is a TaggedIOException decorator the given tag.
 
Methods inherited from class java.lang.Throwable
fillInStackTrace, getLocalizedMessage, getMessage, 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

TaggedIOException

public TaggedIOException(IOException original,
                         Serializable tag)
Creates a tagged wrapper for the given exception.

Parameters:
original - the exception to be tagged
tag - tag of this exception
Method Detail

isTaggedWith

public static boolean isTaggedWith(Throwable throwable,
                                   Object tag)
Checks whether the given throwable is tagged with the given tag.

This check can only succeed if the throwable is a TaggedIOException and the tag is Serializable, but the argument types are intentionally more generic to make it easier to use this method without type casts.

A typical use for this method is in a catch block to determine how a caught exception should be handled:

 Serializable tag = ...;
 try {
     ...;
 } catch (Throwable t) {
     if (TaggedIOExcepton.isTaggedWith(t, tag)) {
         // special processing for tagged exception
     } else {
         // handling of other kinds of exceptions
     }
 }
 

Parameters:
throwable - The Throwable object to check
tag - tag object
Returns:
true if the throwable has the specified tag, otherwise false

throwCauseIfTaggedWith

public static void throwCauseIfTaggedWith(Throwable throwable,
                                          Object tag)
                                   throws IOException
Throws the original IOException if the given throwable is a TaggedIOException decorator the given tag. Does nothing if the given throwable is of a different type or if it is tagged with some other tag.

This method is typically used in a catch block to selectively rethrow tagged exceptions.

 Serializable tag = ...;
 try {
     ...;
 } catch (Throwable t) {
     TaggedIOExcepton.throwCauseIfTagged(t, tag);
     // handle other kinds of exceptions
 }
 

Parameters:
throwable - an exception
tag - tag object
Throws:
IOException - original exception from the tagged decorator, if any

getTag

public Serializable getTag()
Returns the serializable tag object.

Returns:
tag object

getCause

public IOException getCause()
Returns the wrapped exception. The only difference to the overridden Throwable.getCause() method is the narrower return type.

Overrides:
getCause in class Throwable
Returns:
wrapped exception


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