Difference between Dagger and ButterKnife Android

问题:

Can anyone point out the difference between Dagger and Butterknife? I know that Butterknife is a view injection library and Dagger is a dependency injection library. But the documentation online seems a bit overhead for me. According to Butterknife documentation, you can do non-activity injections as well, which is what Dagger does? Or did I misunderstand something?

回答1:

ButterKnife is targeted to inject views only. Non-activity injection just means that you can provide your own view root to inject views from (like with manually inflated views, etc.). Dagger is a bit more complicated. It can inject anything you want as long as you specified Module - class which satisfies those dependencies (alternatively you can use constructor injection).

As a bottom line - I would say ButterKnife helps you to avoid all that boilerplate code for creating views (aka (TextView)findViewById(R.id.some_text_view);. Nothing more. Under the hood it still does all that boring code. So it is not really an injection..

Also it worth mentioning that Jake Wharton is one of the developers for both those cool libs :)

Here is some useful links:

Dagger sample project on GitHub

Dagger presentation on Devoxx (Jake Wharton)

Dagger hangout with Dagger devs

Don't have much of useful ButterKnife links. It really simple and straight forward though, so hopefully you don't need any

回答2:

Here is a link to the Buterknife documentation. It's very straightforward. However, what the documentation doesn't say but the design of Butter Knife implies is that you can also use Butter Knife in custom views. Just replace "this" with "context" or "getContext" so you determine the scope.

Link: http://jakewharton.github.io/butterknife/

I combine Butter Knife, parcelable and easyAdapter for list views in my project. Reason is less boilerplate and with parcelable faster and cleaner parceling. So if you have a lot of ListViews, I recommend this approach.

Links:

https://github.com/johncarl81/parceler

https://github.com/ribot/easy-adapter

回答3:

The difference is pretty straightforward: A butter knife is like a dagger only infinitely less sharp.
As it is pointed out in the documentation.

回答4:

@JakeWharton's answers it partially in the comment:

TL;DR: They complement each other. Use Butterknife for injecting views, Dagger for the rest.

If you use Dagger to try and inject views you're going to have a very bad time :) Try to think of Butter Knife as a means of binding views rather than injection. I only called it injection because all the RoboGuice converts were complaining about lack of "view injection" with Dagger. It's not really injection at all. Like the answer mentions, it's just a way to reduce boilerplate. Under the hood it's just calling findViewById like you would!

回答5:

ButterKnife was made to simplify registering click listeners, and to reduce the boilerplate provided by findViewById() calls.

Dagger and Dagger2 are general purpose dependency injection systems.

Ignore the text on Guice and MVVM, and read Dependency Injection and The Android Way. This pretty much answers what Dagger is meant to do and simplify.

https://spring.io/blog/2011/08/26/clean-code-in-android-applications