What is the design pattern being used? [closed]

I'm learning about Design patterns in java and I can't understand which one is this and why?

I especially confuse the facade and factory design patterns.

public abstract class Ghost {
  public Ghost() { System.out.println(getClass().getName()); }
  public abstract void tick(Shell shell);
  public void tock(Shell shell) {}
}
public class A extends Ghost {
  public void tick(Shell shell) { shell.use(new C()); }
}
public class B extends Ghost {
  public void tick(Shell shell) { shell.use(new A()); }
  public void tock(Shell shell) { shell.use(new A()); }
}
public class C extends Ghost {
  public void tick(Shell shell) { shell.use(new B()); }
  public void tock(Shell shell) { shell.use(new A()); }
}
public class Shell {
  Ghost _ghost = new A();
  public void tick() { _ghost.tick(this); }
  public void tock() { _ghost.tock(this); }
  public void use(Ghost ghost) { _ghost = ghost; }
}
public class GhostInTheShell {
  public static void main(String args[]) {
    Shell shell = new Shell();
    shell.tick();
    //!2.7
    shell.tick(); shell.tock(); shell.tick();
  }
}