Obtaining a class object class what way?

The first way: the object obtained by the class itself
       Class classname = this .getClass ();  

the second way: by acquiring parent class object instance of a subclass of
        Sub sub = new Sub (); Class clazz = sub.getClass () ;
       class parentClass clazz.getSuperclass = ();

third way: by class name (class full path) is added .class get the object         class forClass = ** ** ClassName.class; (classes in the package. .class plus path)




the fourth embodiment: the object acquired by the string class name class forName = Class.forName ( "** ** className.."); such as: class = forName the Class.forName ( " com.itheima.Sub ");  in this way it is used in the jdbc.