Memento Design Pattern

The Memento design pattern provides a way to store previous states of an Object easily. It has 3 main classes: 1. Memento: The basic object that is stored in different states.  2. Originator: Sets and Gets values from the currently targeted Memento. Creates new Mementos and assigns current values to them.  3. Caretaker: Holds an ArrayList that contains all previous versions of the Memento. It can store and retrieve stored Mementos.