Dependency Injection with setter injection ?

[Raza Mohd]

hi All,

I am new to Spring . I was going through An article on spring injection dependency. I read following thing.

in case of Constructor Injection the dependencies are handed over at the time of object instantiation of the dependent objects whereas In case of Setter/Mutator Injection the dependencies are injected after the dependent object has already been created

If i have a Interface IUserService . Code is like that.

public class DetailAction extends ActionSupport
{

private IUserService  userService;

public IUserService getUserService() {
		return userService;
	}

	public void setUserService(IUserService userService) {
		this.userService = userService;
	}

public String  getDetails() {
		log.info("called [.... getDetails]");
		userLst = userService.findUser();
		log.info("List of users"+userLst.size());
		return "success";
		
	}
}

then please make me clear that is userService is a dependent component??
And let me know that who create the dependent object In context of following article.

[David Newton]

Spring handles object instantiation for either constructor or setter injection.

[Raza Mohd]

ok So, is userService in my case is the dependent component?

and does Spring first creates the object then injects the dependency for the dependent object?

[David Newton]

Raza Mohd wrote:ok So, is userService in my case is the dependent component?

I don't know what that term means in this context.

and does Spring first creates the object then injects the dependency for the dependent object?

What do you think?

[Raza Mohd]

I think it first creates the object !
as we are calling a method findUser() without instantiating UserService class with implements IUserService.
how can a method be called without object.

it clears that Spring container manages the object instntiation .