Applet compiled in version 1.5 wont run on JRE 1.4


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Thread: Applet compiled in version 1.5 wont run on JRE 1.4

  1. #1
    Join Date
    Jan 2006
    Location
    Ireland
    Posts
    35

    Applet compiled in version 1.5 wont run on JRE 1.4

    Hi,

    When I view my webpage a grey box appears where my applet should be, I get the following message from the java console...


    java.lang.UnsupportedClassVersionError: MyApplet (Unsupported major.minor version 49.0)


    I believe this problem arises when I try to run the applet (which was compiled with java version 1.5) in a browser that supports JRE version 1.4

    My question is this...

    How did Sun Micro allow this situation to arise, surely they should have ensured that version 1.5 is compatible with all previous versions

    Will future versions of internet explorer support JRE 1.5

    If I compile the program in version 1.4 can I then run the applet in all browsers (ie. both JRE version 1.4 and 1.5) ?

    Any thoughts are appreciated

  2. #2
    Join Date
    Dec 2004
    Location
    San Bernardino County, California
    Posts
    1,468
    This is not a matter of your applet being compiled with a 1.5 compiler - it is a matter of the language elements you are using in your applet. The jre which is resident on the client machine must support those language elements. If you are using 1.5 introduced features, they won't be supported on older installations of the jre.

    If you need these features, convince your users to upgrade their jre installations. If not, modify your applet so that it uses nothing introduced with 1.5.

  3. #3
    Join Date
    Jan 2006
    Location
    Ireland
    Posts
    35
    Thanks nspils,

    I shall have a look at my code and see what I need to change

  4. #4
    Join Date
    Feb 2006
    Location
    Cologne - Germany
    Posts
    271
    usually software is upcompatible and not downcompatible.
    or ever tried running a win2k specific application on a win98 machine?

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