Java update broke a Java app?

Bryan Sant bryan.sant at gmail.com
Fri Nov 18 11:03:11 MST 2011


On Fri, Nov 18, 2011 at 8:33 AM, S. Dale Morrey <sdalemorrey at gmail.com>wrote:

> Hi Everyone,
>
> I've got a question, I'm hoping someone with experience on the Java
> self-update mechanism might have an answer for.
>
> My wife uses a custom Java app for her job which involves writing ad-copy.
> The app interfaces directly to a NoSQL db and allows her to translate
> the engrish (piss poor chinese translations) product descriptions
> contained in her company's database into actual english.
>
> Last night about 11pm, her system performed an auto-update for Java,
> this morning the app won't launch for her anymore.
> What's odd is that it's working here just fine.
>
> The app is written in Java 7.
> I only have 7 installed and she has 6 & 7, but otherwise we have
> identical systems.
>
> Is it possible that the java update could have changed her default JVM
> back to Java 6?
> If so is there any way to prevent that sort of behavior in the future?
>
> Thanks in advance!
>

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)?

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


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