Why Should I Use Constructor Injection?

https://reflectoring.io/constructor-injection/

Types of Spring @Autowired

 We can implement dependency injection with:

https://www.baeldung.com/properties-with-spring

https://reflectoring.io/constructor-injection/

• constructor-based injection

@Component
class Sandwich {

  private Topping toppings;
  private Bread breadType;

  @Autowired
  Sandwich(Topping toppings, Bread breadType) {
    this.toppings = toppings;
    this.breadType = breadType;
  }

}

setter-based injection

@Component
class Cookie {

  private Topping toppings;

  @Autowired
  void setTopping(Topping toppings) {
    this.toppings = toppings;
  }
}

field-based injection.
@Component
class Pizza {

  @Autowired
  private Topping toppings;
}

Spring Bean: Is autowired attribute initialised before constructor?

https://stackoverflow.com/questions/26230493/spring-bean-is-autowired-attribute-initialised-before-constructor

1. First Constructor is called
2. Then Spring Bean is initialized