This is because the className
value which you are passing as argument forforName(String className)
method is not found or doesn’t exists, or you a re passing the wrong value as the class name. Here is also a link which could help you.
1. https://docs.oracle.com/javase/7/docs/api/java/lang/ClassNotFoundException.html
2. https://docs.oracle.com/javase/7/docs/api/java/lang/Class.html#forName(java.lang.String)
Update
Module not specified
According to the snapshot you have provided this problem is because you have not determined the app module of your project, so I suggest you to choose the app module from configuration. For example: