org.apache.commons.io.input

Class TaggedReader

  • All Implemented Interfaces:
    Closeable, AutoCloseable, Readable

    public class TaggedReader
    extends ProxyReader
    A reader decorator that tags potential exceptions so that the reader that caused the exception can easily be identified. This is done by using the TaggedIOException class to wrap all thrown IOExceptions. See below for an example of using this class.
     TaggedReader reader = new TaggedReader(...);
     try {
         // Processing that may throw an IOException either from this reader
         // or from some other IO activity like temporary files, etc.
         processReader(reader);
     } catch (IOException e) {
         if (reader.isCauseOf(e)) {
             // The exception was caused by this reader.
             // Use e.getCause() to get the original exception.
         } else {
             // The exception was caused by something else.
         }
     }
     

    Alternatively, the throwIfCauseOf(Throwable) method can be used to let higher levels of code handle the exception caused by this reader while other processing errors are being taken care of at this lower level.

     TaggedReader reader = new TaggedReader(...);
     try {
         processReader(reader);
     } catch (IOException e) {
         reader.throwIfCauseOf(e);
         // ... or process the exception that was caused by something else
     }
     
    Since:
    2.7
    See Also:
    TaggedIOException
    • Constructor Detail

      • TaggedReader

        public TaggedReader(Reader proxy)
        Creates a tagging decorator for the given reader.
        Parameters:
        proxy - reader to be decorated
    • Method Detail

      • isCauseOf

        public boolean isCauseOf(Throwable exception)
        Tests if the given exception was caused by this reader.
        Parameters:
        exception - an exception
        Returns:
        true if the exception was thrown by this reader, false otherwise
      • throwIfCauseOf

        public void throwIfCauseOf(Throwable throwable)
                            throws IOException
        Re-throws the original exception thrown by this reader. This method first checks whether the given exception is a TaggedIOException wrapper created by this decorator, and then unwraps and throws the original wrapped exception. Returns normally if the exception was not thrown by this reader.
        Parameters:
        throwable - an exception
        Throws:
        IOException - original exception, if any, thrown by this reader

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