@Autowiring doubt

[akkyy21]

If we Autowire a particular attribute of the class?

would it be considered as a Constructor dependency or a Setter dependency?

[Marten Deinum]

It depends where you put @Autowired...

1. Put it on a constructor argument then it is a constructor dependency
2. Put it on a method a 'setter' dependency
3. Put it on the field neither of the 2 because now reflection is used to inject the dependencies..

[akkyy21]

Thanks.
So, is my understanding right now?

Autowiring has no relation to Injecting dependencies.

Autowiring is a mechanism that enables connecting classes together.
Dependencies are used to set values in the variables of the classes.

[Marten Deinum]

No.. Autowiring has everything to do with injecting dependencies... Connecting classes together IS dependency injection...

[akkyy21]

Thanks again for the response.

So,..

Setter injection mapping :-

<bean id="user" class="com.User" >
<property name="name" value="Eswar" />
<property name="age" value="24"/>
<property name="country" value="India"/>
</bean>

Constructor injection mapping :-

<bean id="user" class="com..User" >
<constructor-arg type="int" value="24"/>
<constructor-arg type="java.lang.String" value="India"/>
</bean>

So, since the mapping is different for both, ideally mapping tells what kind of injection-dependency is followed.
Then I don't understand, how would placing of @Autowiring indicate what kind of mapping is done.

[Marten Deinum]

Then I don't understand, how would placing of @Autowiring indicate what kind of mapping is done.

Have you actually READ my post??

It depends where you put @Autowired...

1. Put it on a constructor argument then it is a constructor dependency
2. Put it on a method a 'setter' dependency
3. Put it on the field neither of the 2 because now reflection is used to inject the dependencies..

public class Foo1 {
  public Foo(@Autowired Bar bar) {}
}

public class Foo2 {
  @Autowired
  public void setBar(Bar bar) {}
}

public class Foo3 {

 @Autowired
 private Bar bar;
}

[akkyy21]

Thanks.

I am still a bit confused as to, why @Autowired will be used, if one can set the dependency without it too.
Anyway, that part, I think I should read the documentation more carefully.

Thanks a ton for the examples and explanation. appreciate it

[Marten Deinum]

If you don't use xml to configure your application you need a way to tell what to inject where... This is the case when you use component-scanning (auto detecting of beans and automatically wire the dependencies, hence the name @Autowire )...