Java different ways of creating objects

Question

Can any one tell me the difference between these two object creation

Method 1 :

Superclass ob = new Childclass();

Method 2 :

Childclass ob = new Shildclass();

What will be the difference between both objects and why.

Thanks, Vijesh

https://docs.oracle.com/javase/tutorial/java/IandI/subclasses.html — Rahul Tripathi, Mar 22 '16 at 13:51
Your Java textbook should explain. If you don’t understand its explanation, I suggest you try asking a more specific question. :-) — Ole V.V., Mar 22 '16 at 13:53

score 1 · Answer 1 · answered Mar 22 '16 at 13:47

The difference is:

Superclass a = new ChildClass();

is declared as a type Superclass instance, meaning it's limited to the members of the Superclass.

ChildClass c = new ChildClass();

is of type ChildClass and has access to all the members of both the ChildClass, and those inherited from Superclass.

Stephen C · Answer 2 · 2016-03-22T13:59:45.890

The object creations are the same. In both cases you are creating an instance of the Childclass.

The difference between those two snippets is in what you do with the object references after the object creation.

By assigning the object reference to a variable of type Superclass you are temporarily "hiding" some aspects of the Childclass-ness of the object. But the object remains an instance of Childclass, as illustrated by this:

Superclass ob = new Childclass();
System.out.println(ob.getClass());  // prints "Childclass"

Java different ways of creating objects

2 Answers2