Everything You Need to Know About Builder Design Pattern

What is design pattern

A design pattern in software engineering is a general, reusable solution to a commonly occurring problem within a given context in software design. It is a template or blueprint that can be applied to solve a specific problem in various situations.

There are several reasons why software developers use design patterns:

Provide Best Practices: They encapsulate the knowledge and experience of seasoned developers, offering a way to follow established design principles.
Improve Code Reusability: By using a proven pattern, you can avoid re-inventing the wheel and adapt the solution to your specific needs.
Enhance Code Maintainability: Well-designed patterns often make code easier to understand and modify, which is important for future maintenance.
Facilitate Communication: Design patterns provide a common language among developers, making it easier to discuss and collaborate on code design.

Key Points

Understanding the problems
1. Too many parameters
1. Telescopic constructors
1. Immutability
1. Order of initialization

Details:

I. Constructor with long parameter

A Java class called PollutionEntry with a long constructor taking country, state, city, place, average, max, min and pollution

II. Telescopic Constructor

A Pizza class with four overloaded constructors, annotated with the questions which constructor to use and which order to maintain

III. Immutability

A slide titled Painting on Canvas, explaining that the canvas size and margin should be unchangeable

A slide titled Network Config, explaining that timeout, cache size and retry settings should be immutable

A slide titled Notification config, explaining that title, subtitle, icon, vibration and ringtone should be fixed after object creation

IV. Order of Initialization

A slide titled Painting on canvas, explaining that size, background colour and margin are set before other objects are painted

A slide titled Document Builder, explaining that the title section is set before the rest of the content

What we will support:

Complex and large number of parameters

Optional parameters

Immutable parameters

Order of initialization

The memorization of the order is not necessary for user

Builder Object:

Kotlin code calling NetworkRequest.Builder with chained addHeader, addQueryParams, setRequestBody and setHttpMethod calls before build

Builder Pattern Implementation

The NetworkRequest class with a private constructor and a nested Builder class exposing the chained setter methods

Builder Pattern In Project

A dependency injection module providing a configured OkHttpClient and a Retrofit instance, each assembled with a builder

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