Java-based polymorphism

3 classA {4      Public voidfun1 () {5System.out.println ("A--->public fun1 ()");6     }7      Public voidfun2 () {8           This. FUN1 ();9     }Ten }; One classBextendsa{ A      Public voidfun1 () { -System.out.println ("B---->public void fun1 ()"); -     } the      Public voidFun3 () { -SYSTEM.OUT.PRINTLN ("B------>public void Fun3 ()"); -     } - }; +  -  Public classPolDemo1 { +         Public Static voidMain (string[] args) { Ab b =NewB ();//instantiating an object atA a=b;//Upward Transformation Relationship - a.fun1 (); - A.fun2 ();
A.fun3 (); There is no error -            } -}；

Output:

B---->public void fun1 ()
B---->public void fun1 ()

Method overrides, the upward transformation first executes the overriding method, then executes the parent class;

Java-based polymorphism