Best practices for design patterns to improve code maintainability

Best practices improve code maintainability through design patterns, including: 1. Dependency injection: Injecting dependencies improves testability and reduces coupling. 2. Single responsibility principle: a class is only responsible for one task, improving code readability, maintainability, and scalability. 3. Interface isolation principle: The interface only defines necessary operations to reduce coupling and facilitate maintenance and expansion. 4. Liskov substitution principle: Replacing a base class with a derived class does not affect behavior and enhances flexibility and maintainability. 5. Factory pattern: Separate the responsibility for creating objects and creating classes to improve maintainability and flexibility.

Best practices for design patterns to improve code maintainability

Design patterns are reusable programming solutions , can be applied in different scenarios, aiming to improve the maintainability, readability and reusability of code. Here are some best practices to improve code maintainability:

Dependency Injection (DI)

• Description: Insert dependencies Inject into the class instead of hardcoding.
• Advantages: Improve testability, reduce coupling, and facilitate maintenance and expansion.

Single Responsibility Principle (SRP)

• Description: A class is only responsible for completing a single task.
• Advantages: The code is easier to understand, maintain and expand, and errors are easier to locate.

Interface Isolation Principle (ISP)

• Description: The interface only defines operations that the client really needs.
• Advantages: Reduce coupling, making the code easier to maintain and expand.

Liskov Substitution Principle (LSP)

• Description: A derived class should be able to replace its base class without vandalism.
• Advantages: Improve flexibility and facilitate maintenance and expansion.

Factory Pattern

• Description: The responsibility for creating objects is separated from the class that actually creates them.
• Advantages: Improve the maintainability and flexibility of the code, making it easier to add new types.

Practical case

Consider the following code:

class Customer {
  private int id;
  private String name;
  private OrderService orderService;

  public Customer(int id, String name) {
    this.id = id;
    this.name = name;
    this.orderService = new OrderService();
  }

  public void placeOrder() {
    orderService.placeOrder();
  }
}

Question: This class violates SRP because it Responsible for managing customer information and placing orders.

Solution: App DI:

class Customer {
  private int id;
  private String name;
  private OrderService orderService;

  public Customer(int id, String name, OrderService orderService) {
    this.id = id;
    this.name = name;
    this.orderService = orderService;
  }

  public void placeOrder() {
    orderService.placeOrder();
  }
}

We improved testability by injecting OrderService into the Customer class , reducing the degree of coupling and making the code easier to maintain.

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