jar file problem -

When I try to run jar file from Netbeen then it works fine, but when I try to run from the command prompt I am giving it expaction thread error but when I check my Task Manager, it shows that javaw.exe is running .............. what exactly is this and Why is this error coming in command prompt?

Compile your application like this:

  & gt; ; Play javac -jar example.jar ClassName.java   
:  
  & gt; Java-eg example.jar class name