"jar cvf classes.jar classes.class" is not correct?

I use "jar cvf Test.jar Test.class" to build the jar file.
but when I use java -jar Test.jar ,Some error occured!
(I am now in the director where the jar file locate.)
the error info is :"Failed to load Main-Class manifest attribute from Test.jar "
help please. I cann't resove it!

What part of the test is this on?

Hi Paul Stevens:
Thanks for your responses first.
the Test.java is very simple.
public class Test{
public static void main(String[] args){
System.out.println("hello,world");
}
}

Hi Dragon,
I'm going to move this over to Other Java API. This forum is only for questions directly relating to the SCJP exam.
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Jane Griscti
Sun Certified Programmer for the Java� 2 Platform