Java update broke a Java app?

S. Dale Morrey sdalemorrey at
Fri Nov 18 12:15:23 MST 2011

On Fri, Nov 18, 2011 at 12:14 PM, S. Dale Morrey <sdalemorrey at> wrote:
>> Yes, it is possible.  Is your wife using Windows?  Does she launch the app
>> with a shortcut, or does she just double-click on a .jar file?  When you
>> run "java --version" from a command-prompt, what version is reported (I'm
>> assuming, it will say that it is Java 6 and not 7)?
> Actually that's a good point, we both bought a couple of new Windows 7
> laptops a couple of weeks ago.  And yes she just double clicks the jar
> file.  I'll ask her the output of java --version when I get home
> tonight.
> I wonder how you set the default JVM for Win7 if it turns out to be Java 6?
> Win 7 admin isn't exactly my cup of tea.
>> Java is backward compatible, but not forward.  A Java 6 JRE doesn't know
>> how to read .class files that were compiled with a Java 7 compiler.  That
>> is the most likely explanation.
>> -Bryan
> I've always written to Java 5 or 6 and never tried 7, but I do
> remember a couple of times running a Java 5 app on a 6 machine and
> having it /puke on itself.  Seemed like the message was quite
> articulate about the issue.  On the other hand, my wife's response
> thus far is something along the lines of... "It's throwing some sort
> of error, please fix it."  Didn't really think that gave me much
> leverage to ask more detailed questions.  At least not if I want to
> eat tonight :)

That would be exactly the opposite of what I meant to write.  I meant
running a Java 6 app on a Java 5 machine.

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