Design Patterns

Design patterns are divided into three:

• Creational
• Structural
• Behavioral

The must know patterns for each category are:

• Creational: Singleton, Builder, Factory.
• Structural: Facade, Adapter.
• Behavioral: Strategy, Observer.

Must know concepts

• Abstract Factory
• Adapter
• Composite
• Decorator
• Factory Method
• Observer
• Strategy
• Template Method

Descriptions of communicating objects and classes that are customized to solve a general design problem in a particular context.

Describes simple and elegant solutions to specific problems in object-oriented software design. Implementing these patterns represents more work than doing an ad hoc solution, but you gain increased flexibility and reusability.

Each pattern has four essential elements:

• Pattern name
• Problem
• Solution
• Consequences

Reuse successful designs by basing new designs on prior experience.