Design Patterns (GOF) in Java

Welcome to GOF (Gang of Four) Design Patterns implemented using Java programming. Each design pattern is explained with a problem statement, solution, steps to implement, implementation (source code), and when to use.

Design patterns provide tested, proven solutions to recurring software design challenges. They encapsulate best practices honed over the years and offer a shared lexicon for software developers. While they don't represent finished designs or code, they provide templates to solve problems in various situations.

Design Patterns(GOF)

The GOF Design Patterns are broken into three categories: 

1. Creational Patterns for the creation of objects; 
2. Structural Patterns provide relationships between objects
3. Behavioral Patterns help define how objects interact.

1. Creational Patterns

In software engineering, creational design patterns are design patterns that deal with object creation mechanisms, trying to create objects in a manner suitable to the situation. The basic form of object creation could result in design problems or added complexity to the design. Creational design patterns solve this problem by somehow controlling this object creation.

• Singleton Design Pattern

• Factory Design Pattern

• Abstract Factory Design Pattern

• Builder Design Pattern

• Prototype Design Pattern

• Object Pool Design Pattern

2. Structural Patterns

In Software Engineering, Structural Design Patterns are Design Patterns that ease the design by identifying a simple way to realize relationships between entities.

• Adapter Design Pattern

• Bridge Design Pattern

• Composite Design Pattern

• Decorator Design Pattern

• Facade Design Pattern

• Flyweight Design Pattern

• Proxy Design Pattern

3. Behavioral Patterns

In software engineering, behavioral design patterns are design patterns that identify common communication patterns between objects and realize these patterns. By doing so, these patterns increase flexibility in carrying out this communication.

• Chain of responsibility

• Command Design Pattern

• Iterator Design Pattern

• Mediator Design Pattern

• Memento Design Pattern

• Observer Design Pattern

• State Design Pattern

• Strategy Design Pattern

• Template Method Design Pattern

• Delegation Pattern