What are Design Patterns

A design pattern is a reusable solution to a commonly occurring problem in software design. It represents a general, proven approach that can be applied to various situations to address specific design challenges.

The design patterns are language independent strategies for solving common object-oriented design problems.

Design patterns are an essential tool for software development that can help programmers write more organized, efficient, and reusable code.

They are like pre-made templates for solving common problems that arise in software development, offering a standardized and proven solution for each problem. By using design patterns, programmers can save time, reduce the risk of bugs, and improve the overall quality of their code.

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They are usually divided into categories such as creational, structural, and behavioral patterns, each with its own unique set of solutions.

By learning design patterns in Java, developers can deepen their understanding of object-oriented concepts and improve their ability to design and implement complex software.

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Why learn Design Patterns

When you make a design, you should know the names of some common solutions. Learning design patterns is good for people to communicate each other effectively.

SUN suggests GOF (Gang of Four—four pioneer guys who wrote a book named
“Design Patterns”- Elements of Reusable Object-Oriented Software), so we use that book as our guide to describe solutions.

Design patterns are an essential tool for software development that can help programmers write more organized, efficient, and reusable code.

They are like pre-made templates for solving common problems that arise in software development, offering a standardized and proven solution for each problem. By using design patterns, programmers can save time, reduce the risk of bugs, and improve the overall quality of their code.

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Categories of Design Patterns

Design patterns are generally categorized into three main types:

1. Creational Patterns: These patterns are used to create objects and classes in a way that is suitable for a particular situation. Creational design patterns provide solution to instantiate an object in the best possible way for specific situations.

• Singleton Pattern
• Factory Pattern
• Abstract Factory Pattern
• Builder Pattern
• Prototype Pattern

2. Structural Patterns: These patterns are used to arrange classes and objects to form larger structures. Structural patterns provide different ways to create a class
structure, for example using inheritance and composition to create a large object from
small objects.

• Adapter Pattern
• Composite Pattern
• Proxy Pattern
• Flyweight Pattern
• Facade Pattern
• Bridge Pattern
• Decorator Pattern

3. Behavioral Patterns: These patterns are used to describe the ways in which objects interact and communicate with each other. Behavioral patterns provide solution for the better interaction between objects and how to provide lose coupling and flexibility to extend easily.

• Template Method Pattern
• Mediator Pattern
• Chain of Responsibility Pattern
• Observer Pattern
• Strategy Pattern
• Command Pattern
• State Pattern
• Visitor Pattern
• Iterator Pattern
• Interpreter Pattern
• Memento Pattern

These categorizations are a useful way to understand the different types of design patterns and their intended uses.