layout	title	folder	permalink	categories	tags
pattern	Memento	memento	/patterns/memento/	Behavioral	Gang of Four

Also known as

Token

Intent

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

Class diagram

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