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?
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
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
#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!
The difference is pretty straightforward: A butter knife is like a dagger only infinitely less sharp.
As it is pointed out in the documentation.
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
Related
The idea behind dagger-android is to reduce the boilerplate needed to inject objects. To be even more specific, the idea is to reduce that boilerplate code in Fragments, Activities or any other Android framework classes that are instantiated by the OS.link
So, here as i made the bold text, what are the boilerplate code in android and how dagger2 reduce it?
I think you got it wrong Dagger does not meant to remove boiler plate code (It does in a way but it certainly not build for that purpose). That's what a library serve it perform the all the heavy lifting and provide us easier ways to implement the feature .
The feature dagger provide is Dependency Inversion principle its the D from SOLID principle .
Dagger is a Dependency injection framework which takes care of providing dependencies which the scopes provided its annotation base so its runtime safe. Its maintains a Dependency Graph of whole application the dependency we provides in our modules and inject them as they needed . That's all it does So yeah now you do not have to create objects in Activity/Fragment if you inject them if that's what you call boiler plate then you won't need it anymore . But IMO its not a boiler plate . Dependency Inversion principle Also make it easier to write code in TDD fashion.
You can build your own DI module if u don't want to use Dagger but why?
I saw this question, but it was from the point of testability.
In my case, I see Dagger as an additional complexity for code (create #Provides methods, inject methods, remember all the right annotations). Should I still use Dagger if I just want to inject singletons like SharedPrefUtils? Is it really faster for this case?
Dagger was not made for creating Singletons and if creating a singleton is the reason you want to add Dagger to your project, then its an overkill. Dagger is a dependency injection framework that helps make the process of providing and injecting dependencies easier in a complex project. The #Singleton would help you ensure that only a single instance of a class is created when satisfying your dependencies it is not an alternative to the Kotlin object, they could even be used together. So like other answers and comments suggest if you have a small project and you could use simple design patterns like Singleton, Factory, and Abstract factory pattern.
Dagger is a dependency injection framework. For very simple applications, you can go with manual injection which will save you time because dagger can be difficult to set up and work with from the beginning. However, if you are planning on a production application which has a very long life span and will contain multiple UIs and multiple classes, then you are definitely going to need a dependency injection framework or strategy along the line.
There is an alternative for Kotlin which is Koin. Koin works more like a Service Locator and is easier to set up than Dagger but I will prefer dagger because it has survived the test of time.
It is up to you whether you want to use automatic dependency injection or manual injection so in the end you weigh your options and see what best fits your use case.
I'm reading about Dependency Injections and found 2 libs that get my attention, AndroidAnnotations and Dagger 2. What I saw is that AA has a lot of functionalities including DI, but most of the developers are using Dagger 2 for DI.
I was wondering what is the diference between DI with AA and DI with Dagger 2? If I use AA it means I don't need Dagger 2?
I couldn't find much information for DI with AA and comparison with other libraries.
Any info would help a lot.
I do not think AA and Dagger can be compared.
Dagger is a general dependency injection library, with lots of capabilities. It is designed to run on Android as well, but it does not need Android, it can be applied on pure Java projects. It has lots of dependency injection features for a fully code-generation based dependency injector.
AndroidAnnotations is an annotation-based framework for Android. It does have a limited dependency injection module (which is only a small subset of AA), however that is not its main feature. It adds annotation based, boilerplate removing APIs for lots of thing for Android, which are used in every project and normally require an awful lot of unnecessary code, like view and resource injection, event handling, instance state restoration, threading, etc. You can see all the use cases of AA here.
Dagger and AA can coexist, actually it really makes sense to use the sophisticated dep injection from Dagger and the lot of features of AA together (i do in all of my projects).
Disclaimer: i am an AndroidAnnotations developer.
recently I have created one sample application by implementing Dagger 2 and Android Architectural Components (Room and Viewmodel) which can help you understand dependency injection using dagger library along with MVVM architecture.
Here is the github project link
I have heard there two major dependency injection libraries used in android one is roboguice and the other one is ButterKnife the main difference between them is roboguice is run time and buttter knife is compile time,so i am confused which has better performance on application wheather its run time or compile,if any idea throws your thoughts here.
Butter Knife will always be faster because it's based on code generation rather than reflection.
However, you can't call what it does dependency injection. It's just view lookup. It could potentially be called view binding as well. The fact that it refers to itself as "view injection" (note the quotes) is a tongue-in-cheek joke.
I've been using Roboguice for 3 months and I think it's a really close approximation of what Spring framework does (using injection). Roboguice is really powerful and lets you inject views, Interfaces and classes (even with the app/activity context if you need it).
Even, If you are worried about Roboguice performance, they've launched Roboblender which helps to improve significantly Roboguice performance.
You may find Roboguice documentation in the following Github link
Butterknife does not seem to me a dependency injection library. Rather than I can call it a view library which makes binding easier, reduces findViewById(...) statements. There is an article comparing these two libraries http://java.dzone.com/articles/dependency-injection-roboguice
I am evaluating Dependency Injection (DI) frameworks for an Android app. The top contenders are: Dagger (with Butter Knife) and Android Annotations. I understand that Dagger and ButterKnife are from the same source- square and they complement each other. Here're are the key matrices that I am looking for:
Ease of use (our build is based on Gradle and we use Android Studio IDE)
Testing support (we use Robotium for functional testing and RoboLectric for unit testing)
Performance (DI frameworks use reflection, which one is faster?)
AndroidAnnotations
uses compile time annotation processing. It generates a sub class with an underscore apppended to the original name (MyActivity_ generated from MyActivity). So to have it work you always have to use the generated class for references instead of your original class.
It has a very rich feature set, see the list of available annotations.
Butterknife
uses also compile time annotation processing, but it generates finder classes which are used by a central class (ButterKnife). This means that you can use your original class for referencing, but you have to call the injection manually. A copy from the ButterKnife introduction:
#Override public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.simple_activity);
ButterKnife.inject(this);
// TODO Use "injected" views...
}
The feature set is not so rich, ButterKnife supports view injection (AndroidAnnotations equivalent would be #ViewByIdand #ViewsById) and some event binding (for a complete list see the namespace directory here, just count the OnXXX event annotations).
Dagger
is a DI implementation for Android, similar to Guice. It also uses compile time annotation processing and generates object graphs which you use for manually injection. You distinguish between application object graph and scoped object graphs for injecting e.g. in activities. Here you see an Application.onCreate example:
#Override public void onCreate() {
super.onCreate();
objectGraph = ObjectGraph.create(getModules().toArray());
objectGraph.inject(this);
// use injected classes
}
I found it is harder to start with dagger, but this might be only my experience. However see some videos here for a better start: 1, 2
From the feature set point of view I would say that Dagger implements functionalities which could be compared to AndroidAnnotation's #EBean and #Bean functionality.
Summary
If you are comparing ease of use, testing support and performance I can't find much difference between using AndroidAnnotation and ButterKnife+Dagger. Differences are in the programming model (use classes with _ instead of using the original ones and call the injection manually) and in the feature set.
AndroidAnnotation gives you a full list of functionalities, but ties you to certain libraries. For example if you use it's rest api you have to use Spring Android. You also have annotations for features like OrmLite (#OrmLiteDao) regardless if you use OrmLite or not.
At the end it is a matter of taste, at least in my opinion.
Here is the Nice article in Dzone blog.
We to need to compare the features of each, such as :
Minimum Jars required
ActionBarSherlock compatibility
Injection for click listeners
POJO injection
Performance
Only Pojo Injection missing in butterknife! So looks like Butterknife is the winner!
Source
Google does ask specifically not to use dependency injection.
But by reading their request they seem to be referring more to the Guice and reflection based DI library's. Libraries such as android annotation use no reflection instead employing compile time generated code, while butterknife and dagger uses a small amount of reflection optimised for android but are supposedly slightly more powerful than android annotation. It really depends on the project and how much of a performance hit you are willing to take. In my opinion just using butterknife is sufficient to speed up code development by itself. If you need slightly more use android annotation and lastly if you are willing to take a slight performance hit due to reflection the best option without absolutely destroying performance with a powerhouse Guice based reflection use dagger + butterknife.
You should give a try at Toothpick.
Toothpick is (per the README):
pure java
fast, it doesn't use reflection but annotation processing
simple, flexible, extensible & powerful, robust & tested
thread safe
documented & Open Source
scope safe : it enforces leak free apps
test oriented : it makes tests easier
it works very well with Android or any other context based framework (such as web containers)
It can even be faster than Dagger 2 in most cases, and it's much simpler.
Note: Yes, I am one of the authors.
Use Android Annotations or Butterknife to ease your coding. But don't go for Roboguice! Roboguice forces your activies, fragments to extend to roboguice classes. Not fun, at all!
Dagger 2 is a much better option. You can use it along with Android Annotations if you'd like. I would just use Android Annotations for a simple app, but these days is good to work more with Dagger.
Seems like Google chooses dagger, as they are developing it jointly with Square, who created it.
Concerning Butterknife and Dagger themselves, there is the SO question difference-between-dagger-and-butterknife-android which clarifies how they complement each other.
The reddit-thread mentioned by #ChrLipp has someone who used all three on the same project, speaks highly of dagger+butterknife but also gives AndroidAnnotations its place:
For dependency injection, butterknife is used for Views, Dagger is
used for all objects and is highly recommended and Android Annotations
creates more of a framework for developing Android instead of
injecting objects into your classes so each library are quite
different from each other. Dagger is equivalent to Guice but is much
much faster. Dagger is more powerful then ButterKnife and Android
Annotations as it injects all objects rather than ButterKnife and
Android Annotations which only inject a certain set of objects.
Dagger can be a pain to setup and configure but is well worth it once
you have it done. But then again, because these are all quite
different from each other, it all depends on what your needs are for
the project.
Also, speaking of each one being quite different, in your project you
can use ButterKnife, Android Annotations and Dagger all in the same
project if you really want to. They each have the same idea but do
something different so you could use them all.
Eventually if you use one of the three, you'll have a hard time transitioning to Android's databinding. That's what's fastest if you need to consider performance:
https://developer.android.com/tools/data-binding/guide.html