When casting a derived class to a parent class do you lose data?

Question

For example

public class parentClass{
     //stuff done
 }

public class derivedClass extends parentClass{
    // has data that parentClass does not
}

// some function 
public parentClass foo(parentClass myVar){
    return myVar
}

// ... later ...

{
  ...
   derivedClass dClass1 = new derivedClass();

   parentClass pClass = foo(dClass1);

   derivedClass dClass2 = (derivedClass)pClass;
 ...
}

Was data lost between dClass1 and dClass2? I am not sure, I think the answer is no. I know that if I was using doubles and ints then data IS lost, but that isn't using pointers and objects, so I wasn't sure.

Answer 1

You cant cast objects so you can't lose data. All you can do is cast the reference to an object and this doesn't alter it in any way.