README.md

THE ITERATOR AND COMPOSITE PATTERNS

Well-Managed Collections

1. The Iterator Pattern

1.1. The Problem

Objectville Diner and Objectville Pancake House is merging into one business, so they need to integrate their two menu implementations. However, a slight problem occurs.

The Objectville Diner uses an Array to store the menu items, while the Objectville Pancake House stores their menu items in an ArrayList. Neither of them is willing to change their implementations because they have too much code that depends on those implementations.

How would you help them to solve this problem?

1.2. The Definition of Iterator Pattern

The Iterator Pattern provides a way to access the elements of an aggregate object sequentially without exposing its underlying representation.

1.3. Demo Diagram

2. The Composite Pattern

2.1. The Problem

Come back to the above menus. They want to make their menus more flexible to contain even sub-menus, not only menu items. See the picture below for a demonstration. How will you structure their code to meet this requirement?

2.2. The Definition of Composite Pattern

The Composite Pattern allows you to compose objects into tree structures to represent part-whole hierarchies. Composite lets clients treat individual objects and compositions of objects uniformly.

2.3. Demo Diagram