Help ... Solve Clas Formatter error ...

Question

dear all ,
any body know about class formatter error ..
After i installed jdk1.6 in my system
my java programs are not working now .
If i run any program class formatter error throws .....
For example
class t {
public static void main(String args[]) {
System.out.println("testing");
After i compiled the sample programs
when i run the program ...
$ java t
Exception in thread "main" java.lang.ClassFormatError: t (unrecognized class file version)
at java.lang.VMClassLoader.defineClass(libgcj.so.7rh)
at java.lang.ClassLoader.defineClass(libgcj.so.7rh)
at java.security.SecureClassLoader.defineClass(libgcj.so.7rh)
at java.net.URLClassLoader.findClass(libgcj.so.7rh)
at gnu.gcj.runtime.SystemClassLoader.findClass(libgcj.so.7rh)
at java.lang.ClassLoader.loadClass(libgcj.so.7rh)
at java.lang.ClassLoader.loadClass(libgcj.so.7rh)
at gnu.java.lang.MainThread.run(libgcj.so.7rh)
The above error throws ..
not only this sample program.. I run any example in the java demos also not working
Any body know please help immediately ................

Answer 1

you did this
I just upgrade my jdk 1.5.0_09 to 1.6.0 and when you run java -version, you can see that it is not the sun jdk but the gnu libgcj...
$ java -version
java version "1.4.2"
gij (GNU libgcj) version 4.1.1 20070105 (Red Hat
4.1.1-51)i don't know how the libgcj works because i removed it.
if you wanna remove it, do:
sudo apt-get remove <gnu_libgcj> (i don't know exactly the name!)
and after install the sun sdk...
don't forget to set the classpath of java if it is not done during the install... (look into your .bashrc)
try an
sudo apt-cache search sun
with the result...
sudo apt-get install <sun_jdk> (i don't know exactly the name!)
when everthing is done, do:
vi t.java
in the t.java file, write:
class t{
        public static void main(String[] arg){
                System.out.println("t class");
}after, do a
javac t.java
and
java t
everything should work !