Design Patterns are nothing but documented and tested solutions for recurring problems in a given context. So, in simple words, we can say that the Design Patterns are reusable solutions to the problems that as a developer we encounter in our day to day programming. Design Patterns are basically used to solve the problems of object generation and integration.

The Design Pattern is not a silver bullet. Let us understand what it means. While developing your project you know your project requirement better. We have many design patterns. Take the design pattern as a reference and see does the design pattern does really solve your project problem. If yes, then only use the design pattern.

Do not overdo design patterns. One thing you need to remember is that the design patterns are for projects and projects are not for patterns. I saw many developers are enforcing the design pattern into their project which makes the project messy. So, use only when it required.

Types of Design Patterns

Gang of Four categorized the Design Pattern into three main categories based on the three problem area of software architecture. They are as follows.

Creational Design Pattern

Structural Design Pattern

Behavioral Design Pattern

Creational Design Patterns:

If you have a huge project with a lot of classes, a lot of classes mean you are going to deal with a lot of objects. So you need to create different objects (like new Customer(), new product(), new invoice(), etc.). If these objects creations are scattered on the client code, then it leads to lots of complicated logic at the client code. If the object creations are not centralized then it leads to very complicated code. The Creational Design pattern centralized the object creation logic.

As the name says these design patterns deal with object creation and initialization. Creational design pattern gives the programmer more flexibility in deciding which objects need to be created for a given case. Examples of Creational design patterns category: Singleton, Factory, Builder, Prototype, Fluent Interface, Factory Method, and Abstract Factory.

Structural Design Patterns:

Sometimes you need to change the structure of a class or you can say the relationship between the classes but you don’t want the project to be affected. For example, if you have a customer and product class and the product class is used inside the customer class making one to many relationships. Tomorrow, as the project proceeds, the customer wants to keep away the product class as they want to use the product and customer class independently. This is a structural change and you don’t want this structural change to affect your project. This is where the Structural Design Pattern helps us. In simple words, this pattern focuses on the decoupling interface, implementation of classes, and its objects. Examples of Structural design patterns category: Adapter, Facade, Decorator, Composite, Proxy, Flyweight, and Bridge Design Pattern.

Behavioral Design Patterns:

Sometimes you want to change the behavior of a class and again you want it to affect other classes of the project. For example, you have an Invoice class which currently applying taxes as 18%. Tomorrow if you have to add another extra tax. That means you are changing the behavior of a class. To solve such type of Behavioral issues Behavioral Design Pattern comes into the picture.