Java: Upcasting and Dynamic Dispatch

It restricts calls to superclass methods. Frame the concept in practical terms so you can explain it during interview discussion.

Upcasting an object restricts method calls to those defined in the superclass, even if the actual object is a subclass with additional methods. This means that while you can call overridden methods, you cannot call subclass-specific methods without downcasting. For example, a `Product` reference to a `Book` object can call `display()` if overridden but not any new methods defined in `Book`.