您可以通过 Java 中的超级 class 访问子 class 变量吗

Question

Can I access my subclass variable via super class instance?

For instance I create my super class object in Main, and then I want to know the value of variable in the sub class. Is it possible to do so? Thanks.

Answer 1

No this goes against the inheritance principle. It is like asking if a previous gen device will have access to the newer features introduced in the next gen device based on this.

A subclass can access non private members of parent class but not vice versa. It doesnt make sense as the language syntax doesn't ever allow access to child from parent while the opposite is possible through methods and keywords like super.

So it is better that you rethink the way you are thinking of using inheritance abd refactor your core to meet the requirement as this certainly wont work

Answer 2

If class B extends class A and you have an A object, then you can always convert it to its subclass, B in this case. Consider the following:

A a = new A();
B b = (B)a;

afterwards, you can always reach B members via b. You can do it in an inline manner as well, via ((B)a) .