Design principles and coding conventions in Java

Java is a widely used programming language. In order to make programs easy to maintain and expand, the Java community has developed many design principles and coding specifications. This article will introduce several of the most important design principles and coding standards.

1. Design principles

1. Single Responsibility Principle (SRP)

The Single Responsibility Principle requires that each class or method should have only one responsibility. This means that if a class or method handles too many tasks, it should be split into smaller classes or methods. This makes programs easier to understand, test, and maintain.

For example, a class that handles orders should only be responsible for processing order-related operations and should not contain code unrelated to payment, inventory, etc.

2. Open-Closed Principle (OCP)

The Open-Closed Principle emphasizes that software entities (classes, modules, functions, etc.) should be open to extensions and closed to modifications. This means that we should meet new requirements by adding new functionality rather than modifying existing code.

For example, we can use interfaces and abstract classes to implement the open and closed principle. When we need to add new functionality, we can write a new class that implements a new interface or inherits an abstract class to implement the functionality instead of modifying the original code.

3. Dependency Inversion Principle (DIP)

The Dependency Inversion Principle requires that abstraction should not depend on concrete implementation, but that concrete implementation should depend on abstraction. This means that we should not use concrete classes in our code but should use abstract classes or interfaces.

For example, if we define a business logic class, it needs to use a database operation class. We should define a database operation interface, and then write a class that implements the interface to provide data access functions, instead of directly calling the specific implementation class of the database operation in the business logic class.

2. Code specifications

1. Variable naming

Variable naming should be descriptive and easy to understand. Variable names should use camelCase and the first letter should be lowercase. For example, the variable name is customerName.

2. Class Naming

Class names should use camel case notation starting with an uppercase letter. Class names should be clear, concise, and reflect the responsibilities and functions of the class. For example, the class name is OrderService.

3. Method Naming

Method names should use camel case naming starting with a lowercase letter. Method names should be clear and concise, reflecting the function and return value of the method. For example, the method is named getOrderById.

4. Code Comments

Code comments should be descriptive and easy to understand. Comments should reveal the intent of the code but should not be overly detailed. Most of the time, good code itself is the best documentation.

5. Exception handling

Java exception handling should be as specific as possible to avoid catching all exceptions. Each exception should have clear semantics so that it can be quickly located and fixed. If you catch an exception, you should use the most specific exception handling method, such as the throws keyword.

Summary

This article introduces some design principles and coding specifications in Java. These specifications help developers build high-quality, scalable applications through clear, maintainable code.

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