Java Design Patterns

Java Design Patterns

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Java Design Patterns

Pattern Name Meaning Examples in Java API

Factory One class that makes up instances for you, controlled by subclasses getInstance(in Calendar, Format, Local...);
socket constructor;
RMI InitialContext

Iterator Loop over all elements in a collection (or container), visiting each element only once. Iterator;
(or Enumeration for pre Java 2)

Singleton Only one instance may exist for a given class. java.awt.Toolkit

Memento Capture and externalize an object's state for later reconstruction. Serializing and object.

Command Encapsulate requests, allowing queues of requests, undoable operations, etc. java.awt.Command

Model-View-Controller Model represents data; View is what user user sees; Controller responds to user request. Observer/Observable;

Pattern Name	Meaning	Examples in Java API
Factory	One class that makes up instances for you, controlled by subclasses	getInstance(in Calendar, Format, Local...); socket constructor; RMI InitialContext
Iterator	Loop over all elements in a collection (or container), visiting each element only once.	Iterator; (or Enumeration for pre Java 2)
Singleton	Only one instance may exist for a given class.	java.awt.Toolkit
Memento	Capture and externalize an object's state for later reconstruction.	Serializing and object.
Command	Encapsulate requests, allowing queues of requests, undoable operations, etc.	java.awt.Command
Model-View-Controller	Model represents data; View is what user user sees; Controller responds to user request.	Observer/Observable;