Issue1632375

I cannot install jython_21.class on my PC (WinXP) using Java 6 ('java jython_21').

Here is the stack trace:

Exception in thread "main" java.lang.ClassFormatError: Extra bytes at the end of class file jython_21
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(Unknown Source)
        at java.security.SecureClassLoader.defineClass(Unknown Source)
        at java.net.URLClassLoader.defineClass(Unknown Source)
        at java.net.URLClassLoader.access$000(Unknown Source)
        at java.net.URLClassLoader$1.run(Unknown Source)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        at java.lang.ClassLoader.loadClassInternal(Unknown Source)

It works fine with Java 5.

This is a duplicate of 1615929, which is marked as closed/wont fix. Your options are to use an older java, or if you can tolerate pre-release code to use one of the jython 2.2 snapshots. 

A further possibility, if you must use jython 2.1 with java6, is to try installing with an older java, but then running the installed jython with java6 (you'll need to update the path in jython.bat).

This issue needs a FAQ entry, leaving it open as a reminder to write one.

- kz

Oops, sorry I didn't find the original report.

Anyway, the problem here is that the Java scripting site https://scripting.dev.java.net/ explicitly mentions Jython 2.1 as the implementation for Python scripting.

I think an entry in the FAQ would be quite urgent to help people avoid this. I for one wouldn't use a prerelease snapshot without explicitly being told so.

Actually, I am surprised that it doesn't work with Java 6. I was under the impression that one goal of Java 6 was to be more backward compatible than previous releases.

The 2.1 download listing now mentions this, so I'm closing it