Constructor injection vs Field injection

Question

When injecting any services, I have two choices :

Field injection:

 @Inject 
 private MyService myService;

or Constructor injection:

private MyService myService; 

@Inject
public ClassWhereIWantToInject(MyService mySerivce){
    this.myService = myService;
}

Why is Constructor injection better than Field injection?

Answer 1

Do something like (I assume you are using spring-boot or something comparable for your CDI)

public class ClassWhereIWantToInject{

    private MyService myService; 

    @Inject
    public ClassWhereIWantToInject(MyService mySerivce){
        this.myService = myService;
    }
}

At this related question there are some valid arguments why to use injection via constructor instead of injection via field. It boils down to the advantage that you can use initialization via constructor also in non-CDI environment i.e. Unit Test, without the need to add more complex logic.