Intent: Without violating encapsulation, capture and externalize an object's internal state so that the object can be restored to this state later.

Applicability: Use the Memento pattern when

• a snapshot of an object's state must be saved so that it can be restored to that state later, and
• a direct interface to obtaining the state would expose implementation details and break the object's encapsulation

Real world examples:

• java.util.Date

Credits

• Design Patterns: Elements of Reusable Object-Oriented Software