CODEWITHSUNDEEP
java
Đặng Võ
Đặng Võ

Reputation: 23

Is there different between this two ways of creating an object

I just have learned java. I'm fiding the different between this both ways of creating an object

public class A {
}
public class B extends A {
}
public static void main(String[] args){
       A object = new B();
       B object = new B();
}

Upvotes: 2

Views: 74

Answers (1)

Innovation
Innovation

Reputation: 1524

Lets understand it with the example below.

  1. In class A we added a getMethodofA(). So creating reference variable as A or B does not matter. As A is super class getMethodofA() will be available for both the objects of Type A or Type B

  2. In class B we added a getMethodofB(). So creating reference variable as A or B matters. If you create object with reference variable as A, then only getMethodofA() will be available. While If you create object with reference variable B both the methods will be visible getMethodofA() and getMethodofB()

    public class A {

     public void getMethodofA(){
         System.out.println("I am method A")
     }

}

public class B extends A {
     public void getMethodofB(){
        System.out.println("I am method B")
    }
}

public static void main(String[] args){
    A objectA = new B();
    objectA.getMethodofA();//No error
    objectA.getMethodofB();//Compile time error

    B objectB = new B();
    objectB.getMethodofA();//No error
    objectB.getMethodofB();//No error
}

Upvotes: 2

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