CODEWITHSUNDEEP
javavariablesreference
Vikram Singh
Vikram Singh

Reputation: 124

java- reference variable and super class reference variable

public class HelloWorld
{      

     public static void main(String []args)
     {
       Horse obj1=new Horse();
       Horse obj2=obj1;
       Animal obj3;
       obj3=obj2;
       obj2.name="Mustang";
       obj3.name="Alpha";
       obj3.display();
     }
}


class Animal
{   

    String name;
    void display()
    {
        System.out.println("this is "+name);
    }
}

class Horse extends Animal
{

    String name;
    void display()
    {
        System.out.println("this is  "+name);
    }
 }

Hello,i am a beginner in java so sorry if the question is stupid. This is a simple program in which a reference variable obj2 references another reference variable obj1 of the same type. If I change the instance variable "name" they get change in both as both the reference variable are pointing to the same memory I guess. Now i made another reference variable "obj3" of type Animal which is the super class. I made it reference obj2 and now when I try to change the instance variable "name" using obj3 it doesn't work. Can anyone tell me why this happens?

Upvotes: 0

Views: 95

Answers (2)

markspace
markspace

Reputation: 11020

"I was expecting "this is Alpha" as an output but it prints "this is mustang"".

Well, you have two "buckets" named name. Depending on the type, you will access one or the other. Since the obj3 reference thinks it's an Animal, it accesses (and prints) the name from the super class, Animal. So that's why obj3 prints "this is mustang" is because it's accessing the name that is declared inside the Animal class.

Upvotes: 0

bhspencer
bhspencer

Reputation: 13560

You are defining the member String name in both the super type and the subtype. You should remove the name member from the Horse class.

Upvotes: 1

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