A DESCRIPTION OF THE REQUEST :
The Javadoc should specify the information content of the text returned by
getMessage() for IOException and its subclasses. This will make it easier
to write portable / future-proof applications.

(Note: I'm not suggesting that applications should depend on the layout of
the messages; e.g. by attempting to parse out information. That should be
supported by adding extra getters on some IOExceptions; e.g. a getFileName()
method on FileNotFoundException or a getNetworkAddress() method on
java.net.ConnectException.)



JUSTIFICATION :
Consider the following:

    new FileReader(".") ->
            FileNotFoundException(". (Is a directory)")
    new FileReader("nonesuch") ->
            FileNotFoundException("nonsuch (No such file or directory)")

  From this, I can intuit that, on JDK 1.4.2 a FileNotFoundException message string
will contain the offending file name and an OS-specific message saying why the
open failed. And hence, I code my application to do something like this:

     catch (FileNotFoundException ex) {
        System.err.println("Cannot open the config file: " + ex..getMessage());
     }

But will this give me a reasonable looking error message on JDK 1.1, or JDK 6.0,
or ... a Classpath-based VM? I have no way of knowing, because the Javadoc
for FileNotFoundException (and/or FileReader) do not say what the message
text contains.

What alternatives do I have? Well maybe I could use File.exists(), etc to try to
reverse engineer the reason for the exception. But will that cover everything?
I doubt it. For example, the File API does not give me enough information to
know that the 'file' I tried to open is a symbolic link loop. Even if it does, thats
a lot of code I have to include in my application to make it portable.