What is dependency injection and can you give me some examples?

What is dependency injection and can you give me some examples?

Dependency injection is a design pattern used in software development to achieve Inversion of Control. It allows a class to receive its dependencies from an external source rather than creating them itself. For example, in a web application, instead of a service class creating its own database connection, it can receive the connection as a parameter.

Can you explain how it improves code maintainability?

Certainly! Dependency injection improves code maintainability by reducing coupling between classes. This means that changes in one class are less likely to require changes in others, making the code easier to test and modify.

What are some common frameworks that use dependency injection?

Some common frameworks that utilize dependency injection include Spring for Java, Angular for TypeScript, and .NET Core for C#. These frameworks provide built-in support for managing dependencies.

Can you give me a simple code example?

Sure! Here's a simple example in Java:

class DatabaseService {
    public void connect() { /* connection logic */ }
}

class UserService {
    private DatabaseService dbService;

    public UserService(DatabaseService dbService) {
        this.dbService = dbService;
    }
}

// In a main method or configuration class:
DatabaseService dbService = new DatabaseService();
UserService userService = new UserService(dbService);