example problem : hello world, with java, compiler error

i ask my friends to try a testing contest with Hello world as the question problem. i find that every single "java" code is rejected with message "compiler-error". but no problem when they upload C code.

here is the java code :

public class hello {

public static void main(String[] args) { System.out.println("Hello world!"); }

}

here is the error message as admin :

Compilation unsuccessful

Compiling aborted after 1 seconds, compiler output: /usr/sbin/runguard: warning: timelimit exceeded (hard wall time): aborting command /usr/sbin/runguard: warning: command terminated with signal 15 /usr/sbin/runguard: warning: timelimit exceeded (soft wall time)