Structural-Design-Patterns-Note.txt

					Structural
	-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*
	
		=> This design patterns is all about Class and Object composition i.e. 
		How do you want structure the software component.
		
		=> These design patterns are about organizing different classes and objects to form larger structures and provide new functionality.
			

1. Proxy - An object representing another object

		Example: checkbook leaf, credit card, debit card are the proxy for Money and a customer representative to order a product.

		java.rmi.*, the whole API actually.

2. Composite - Gives a unified interface to a leaf and composite.

		Example: File System in Operating Systems, Directories are composite and files are leaves. 
		System call Open is a single interface for both composite and leaf.

3. Decorator - Gives additional feature to leaf, while giving unified interface.
	
		Example: 
			-> Adding discounts on an order 
			-> Gun is a deadly weapon on its own. 
			But you can apply certain "decorations" to make it more accurate, silent and devastating.

		All subclasses of java.io.InputStream, OutputStream, Reader, and Writer have a constructor taking an instance of the same type.

4. Facade - Simplifies multiple complex components with single interface
	
		Example: Control Panel

		javax.faces.context.ExternalContext, which internally uses ServletContext, HttpSession, HttpServletRequest, HttpServletResponse, et

5. Adapter - Provides different interface for an interface.

		Example: Power Adapters

		java.util.Arrays#asList()
		
6. Flyweight - A fine-grained instance used for efficient sharing
		
		Example : Dial tone

		java.lang.Integer#valueOf(int) (also on Boolean, Byte, Character, Short and Long)