[Java Basics] -- access to instance variables and methods after variables are transformed upwards

It is worth noting that when the subclass is transformed up, the member variable is called, that is, the instance variable is the parent class, and the member method is called as the subclass! For example:

Public Class A {int K = 3; Public void test () {system. out. println ("A") ;}} public class B extends a {int K = 90; Public void test () {system. out. println ("B");} public static void main (string [] ARGs) {A = new B (); system. out. println (. k);. test ();}}

AboveProgramOutput result:

3

B