In which cases is it better to use setters for dependency injection in your code?

Setter dependencies (setter injection) are better to use when:

• The dependency is not mandatory for the correct operation of the object, and it can be set later.
• There is a need to change the dependency during the object's lifecycle.
• The object is created without all dependencies, and they are added after creation (for example, during configuration).

Example: if you have a class that can work with different logger implementations, and you want to be able to change the logger without recreating the object, then setters are more suitable than a constructor.

public class Service {
    private Logger logger;

    public void setLogger(Logger logger) {
        this.logger = logger;
    }

    public void doWork() {
        if (logger != null) {
            logger.log("Work started");
        }
        // ...
    }
}