Design patterns provide standardized solutions to common programming problems that can be reused in code. There are three main categories of design patterns: creational patterns that create objects, structural patterns that organize relationships between entities, and behavioral patterns that define communication between objects. Some examples included in the document are the singleton pattern to ensure only one instance, the bridge pattern to separate interfaces from implementations, and the observer pattern to notify objects of state changes.

2. Agenda
• What is Design Pattern?
• Types of Design Pattern
• Live Example

3. Design Pattern
Design Patterns provide standardized and efficient
solutions to software design and programming problems
that are re-usable in your code. Software Architects and
developers use them to build high quality robust
applications.
The authors Erich Gamma, Richard Helm, Ralph Johnson,
and John Vlissides are often referred to as the GoF, or
Gang of Four.

4. Types of Design Pattern
The GoF Design Patterns are divided into 3 categories :
Creational Patterns, Structural Patterns and Behavioral
Patterns.
• Behavioral patterns describe interactions between
objects.
• Creational patterns are used to create objects for a
suitable class that serves as a solution for a problem.
• Structural patterns form larger structures from individual
parts, generally of different classes.

5. Creational Patterns
Abstract Factory Pattern: Create instances of classes belonging to
different families
Builder Pattern: Separate representation and object construction
Factory Method Pattern: Create instances of derived classes
Prototype Pattern: Clone or copy initialized instances
Singleton Pattern: Class with only one single possible instance

6. Structural Patterns
Adapter Pattern: Match interfaces of classes with different interfaces
Bridge Pattern:: Separate implementation and object interfaces
Composite: Simple and composite objects tree
Decorator: Dynamically add responsibilities to objects
Facade: Class that represents subclasses and subsystems
Flyweight: Minimize memory usage by sharing as much data as
possible with similar objects
Proxy: Object that represents another object

7. Behavioral Patterns
Chain of Responsibility: Pass requests between command and
processing objects within a chain of objects
Command: Encapsulate a method call as an object containing all
necessary information
Interpreter: Include language elements and evaluate sentences in a
given language
Iterator: Give sequential access to elements in a collection
Mediator: Encapsulates and simplifies communication between objects

8. Behavioral Patterns continue..
Memento: Undo modifications and restore an object to its initial state
Observer: Notify dependent objects of state changes
State: Change object behavior depending on its state
Strategy: Encapsulate algorithms within a class and make them
interchangeable
Template Method: Define an algorithm skeleton and delegate algorithm
steps to subclasses so that they may be overridden
Visitor: Add new operations to classes without modifying them

9. Thank you