Private attributes are not private

Question

Please consider the following....
// this is a class by someone else.
class A{
  private Integer secretPinNumber =
    new Integer(100);
// and I write this class
class B extends A{
  // there is a method in here but I won't tell
  // you what it is yet.
//When we extend something, the private attributes
// of the extended object are hidden, right?
// Not if you so this.....
// Sneaky method in class B
public Integer stealPINNumber(){
  // cast myself as my super object and since then
  // we are of the same object type, I have access
  // to all private stuff in the super object.
  return ((A)me).secretPinNumber;
// And keep in mind that if I get the OBJECT PINNumber,
// I can change it and the changes will show up in class A.Is this s security hole?
If I have the spec's and code for someone elses class, can I extend it, manipulate it, and become a hacker?
Am I stupid and everyone knows this and I am late to the party?
Thoughts?

Answer 1

The answer to my question is,
I am stupid. I don't pay attention to the details.
For clarification I did the following...
class superclass{
  private Integer PIN = new Integer(100);
  // this is the part in my code that I forgot.
  protected Integer getSecretPin(){
    return PIN;
class sub{
  sub me;
  public sub(){
    me = this;
  // Sneaky stuff
  public Integer getPIN(){
    return
      ((superclass)me).getSecretPin();
}I was tracking down a bug and was writing some output debugging and THOUGHT that I had stumbled on a security thing. On further inspection into the superclass code I had really accessed a protected method. My compiler ignored the casting.
Thanks to all for "Looking into it."
Peace