What is the meaning of the type of reference

Question

class Parent {
    int m;
}

class child extends Parent {
    public static void main(String args[]) {
        Parent x = new Child(); 
    }
}

What is the meaning when we say x is of type Parent? Why do we make use of such referencing while we can use Child x = new Child()?

Downvoted for lack of prior research. – GhostCat Nov 25 '17 at 20:30 — GhostCat, Nov 25 '17 at 20:30

score 0 · Answer 1 · answered Nov 25 '17 at 18:41

0

A List<Shape> can contain rectangles, circles, if those are subtypes of Shape. That's an example for why it's good.

answered Nov 25 '17 at 18:41

Törpetestű

192
10

Read about [polymorphism](https://docs.oracle.com/javase/tutorial/java/IandI/polymorphism.html) for more examples. – Törpetestű Nov 25 '17 at 18:46
I can use a list to add stuff. What can I then do if I have a Parent type reference? I can not add anything to it. – Srinath Shah Nov 25 '17 at 19:17

score 0 · Answer 2 · answered Nov 25 '17 at 20:24

Java resolve the class of an object dynamically. It means that the actual type of an object is resolved over the indicated type.

So, in your example, if Child contains an overloaded method from Parent, this method will be called first before the one inheritted from Parent.

What is the meaning of the type of reference

2 Answers2