About casting objects.

Question

From what I understand, a child class inherits all the properties from its parent class and it may contains additional properties that the parent class does not have. Suppose the parent and child classes are declared as follows.
class Parent {
public void parentX() {}
class Child {
public void ChildX() {}
If I cast a child object to a parent object by doing:
Child c = new Child();
Parent p = (Parent)c;
.. and then cast it back to child class.
Child c2 = (Child)p;
I can still access c2.ChildX(). I was guessing that when you do a upcast (child->parent), the child-specific properties are lost because the parent variable was not allocated enough memory to hold the additional properties. But the above example proves otherwise. Can someone explain?

Answer 1

And casting is mostly telling the compiler what member
methods you have. Because three classes could all have
a method toString() so the compiler needs to know
which of these you mean when you put c.toString().I dont think if you have the same method for both parent and child class, casting will changes which one is called. For example, if a callme() is added as follows:
class Parent {
public void callme() { System.out.println("in parent"); }
class Child extends Parent {
public void callme() { System.out.println("in child"); }
And if you do:
Parent p = (Parent)(new Child);
p.callme();
This will print out "in child". So casting doesnt change which method is called.