Flyweight Pattern

Summary

• The Flyweight pattern reduces the cost of working with large numbers of very small objects.
• The Flyweight pattern is specifically designed to be used when all the following conditions are in place:

• There is a very large number of objects (thousands) that may not fit in memory.
• Most of the state can be kept on disk or calculated at runtime.
• The remaining state can be factored into a much smaller number of objects with shared state.

Class diagram: (see Flyweight Pattern code review)

Usage

Use the Flyweight pattern when there are:

• Many objects to deal with in memory.
• Different kinds of state, which can be handled differently to achieve space savings.
• Groups of objects that share state.
• Ways of computing some of the state at runtime.