i m using window xp and
jdk1.6.0.
i set environment variables as follow
user variables i creat new and in variable name "classpath" and in variable value .;C:\Program Files\Java\jdk1.6.0\bin;.;C:\World
after that i edit system variable as follow
i edit variable "path"
in variable value I append "C:\Program Files\Java\jdk1.6.0\bin" right side so now system variable is"%SystemRoot%\system32;%SystemRoot%;%SystemRoot%\System32\Wbem;C:\Program Files\Java\jdk1.6.0\bin"
After all this I restart p.c.
now i make program and save in c:\world
my program"HelloWorld.java" is as given below

package world;

class HelloWorld
{
public static void main(String a[])
{System.out.println("hello ji kya haal hai");
 }
}

After that in command prompt i run following command:

C:\>set CLASSPATH=.;C:\;

C:\>set CLASSPATH // see what we have in CLSSPATH
CLASSPATH=.;C:\;

C:\>cd world

C:\world\javac HelloWorld.java

C:\world>java world.HelloWorld

Exception in thread "main" java.lang.UnsupportedClassVersion:Bed version n
umber in .class file 
world/HelloWorld)
        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$1(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)

so plz help me

Edited 3 Years Ago by Reverend Jim: Fixed formatting

Hallo

I'm not sure that this is the answer, but be sure to validate that you are compiling to the right version and that your a running with that version of the JRE otherwise your will the get an error as the one you describe.

Hope that helps.

Regards

Per

I don't see a reason to set the CLASSPATH, JAVA is absolutely happy to run just on PATH setup.
Your CLASSPATH seting are strange .;C:\Program Files\Java\jdk1.6.0\bin;.;C:\World What is purpose of that extra semicolon and dot which I marked with red?
And why did you set this CLASSPATH when after restart you change it to C:\>set CLASSPATH=.;C:\;

Make shure to put semicolon on the end of string in PATH %SystemRoot%\system32;%SystemRoot%;%SystemRoot%\System32\Wbem;C:\Program Files\Java\jdk1.6.0\bin; I had bad experience with this missing semicolon while working with MySQL

Edited 3 Years Ago by mike_2000_17: Fixed formatting

most likely an old java.exe, javaw.exe, and possibly javaws.exe got left behind somewhere in the windows installation directory or a subdirectory.
Find and remove those.
Also remove the new JDK and reinstall to a directory with no spaces in it, as it doesn't particularly like that.

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