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Dependency injection in Android Library

I'm working on Android library that other apps will use it.
This library will not have any activity, but it will have Fragments, VM, domain etc.
So far on my apps i worked with Dagger2, and i'm not sure how it will work in library.
Anyone have experience with it? or maybe someone can recommend other library to use for that case (koin?)?
Thanks

Koin is far more easy to use. You can also get rid of annotations and their handling. Suppose we have a class name Helper and needs to be access from different locations.
Implementation Steps:
a) Add Dependency in build.gradle(app).
implementation "io.insert-koin:koin-android:3.3.0"
b) Create a class extend it with KoinComponent
class DIComponent : KoinComponent {
// Utils
val helper by inject<Helper>()
}
c) Initialize Koin by passing it modules in App class
class MainApplication : Application(){
override fun onCreate() {
super.onCreate()
startKoin{
androidLogger()
androidContext(this#MainApplication)
modules(appModule)
}
}
private val appModule = module {
single { Helper() }
}
}
d) Now, to use this class in project (activity/fragment)
class MainActivity : AppCompatActivity() {
private val diComponent = DIComponent()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
diComponent.helper.yourFunction()
}
}

Hilt injection into activity before super.onCreate()

I defined my own LayoutInflater.Factory2 class in a separate module. I want to inject it into each activity in my App, but the point is that I have to set this factory before activity's super.onCreate() method.
When I using Hilt it makes an injection right after super.onCreate(). So I have an UninitializedPropertyAccessException.
Is there any opportunity to have an injection before super.onCreate with Hilt?
Below is my example of module's di.
#Module
#InstallIn(SingletonComponent::class)
object DynamicThemeModule {
#FlowPreview
#Singleton
#Provides
fun provideDynamicThemeConfigurator(
repository: AttrRepository
): DynamicTheme<AttrInfo> {
return DynamicThemeConfigurator(repository)
}
}

You can inject the class before onCreate by using Entry Points like this.
#AndroidEntryPoint
class MainActivity: AppCompatActivity() {
#EntryPoint
#InstallIn(SingletonComponent::class)
interface DynamicThemeFactory {
fun getDynamicTheme() : DynamicTheme<AttrInfo>
}
override fun onCreate(savedInstanceState: Bundle?) {
val factory = EntryPointAccessors.fromApplication(this, DynamicThemeFactory::class.java)
val dynamicTheme = factory.getDynamicTheme()
super.onCreate(savedInstanceState)
}
}
If you need something like this a lot Id recommend creating an instance of it in the companion object of your Application class when your application starts (onCreate). That is before any of your views are created. So you don´t need to jump threw those hoops all the time, but can just access the instance that already exists. This code above won´t be available in attachBaseContext, when you need it there you have to create it in your application class I think.

Is there a way to place override function in a separate file in Kotlin?

I have a Kotlin class that is becoming very large (a couple of hundreds of lines). It's mainly because this class is the listener of several interfaces. Usually, I split my class functions with extensions (and place them in separate files). However, when I try that with override functions, Android Studio gives me this error:
"Modifier 'override' is not applicable to 'top level function'"
So, is there a workaround? How would you split a large file with many override functions? (In Swift, this is done using extensions or Partials in C#). Here is an image for reference in Android Studio and in Xcode. In Swift, we simply add "extension" and that allows us to write code as if we were writing right within the class:

Instead of having your Activity implement listener interfaces, make them into anonymous object members. I think this is usually cleaner anyway.
class MyActivity: AppCompatActivity() {
private lateinit var binding: MyActivityBinding
private val someButtonListener = OnClickListener {
binding.text = "Button clicked!"
}
override fun onCreate(savedInstanceState: Bundle) {
super.onCreate(savedInstanceState)
binding = MyActivityBinding.inflate(layoutInflater)
binding.button.onClickListener = someButtonListener
}
}
Then, you could break these out into another file by making functions that create them.
class MyActivity: AppCompatActivity() {
private lateinit var binding: MyActivityBinding
override fun onCreate(savedInstanceState: Bundle) {
super.onCreate(savedInstanceState)
binding = MyActivityBinding.inflate(layoutInflater)
binding.button.onClickListener = createSomeButtonListener(binding)
}
}
fun createSomeButtonListener(binding: MyActivityBinding) = OnClickListener {
binding.text = "Button clicked!"
}
If you need to call functions in the Activity from these listeners, you'll have to make your Activity a parameter of the function and expose those functions as public, unfortunately. It's not really proper encapsulation, but you typically don't reference Activities from other classes ever, so it's probably not a big deal for it to have some public functions.

This is my code inspired by the answer:
interface MyInterface {
fun itHappened()
}
class MyClass {
lateinit var listener: MyInterface
}
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val myObj = MyClass()
myObj.listener = anonymousListener()
myObj.listener.itHappened()
}
}
fun MainActivity.anonymousListener() = object : MyInterface {
override fun itHappened() {
Log.d("MyTag", "Clicked")
}
}

Kotlin, Dagger and Realm - DI concept problem

I'm starting this brand new project only for fun, but at the first steps I got a problem, there it goes:
I have this class "Note", it's a realm class as you can see below
#RealmClass
open class Note
#Inject constructor (#PrimaryKey var id: String,
var text: String,
var badge: NoteBadge?
) : RealmObject() {
fun getRandomNoteText(): String = "supposed to be random"
}
Then I have my Main activity class, where I already got Dagger working.
class MainActivity : AppCompatActivity() {
#Inject lateinit var note: Note
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
DaggerNoteComponent.create().inject(this)
Log.d("MAIN_ACTIVITY", note.getRandomNoteText())
Log.d("MAIN_ACTIVITY", note.badge?.getRandomBadgeText())
}
}
It got tricky in terms of concepts, the code above doesn't compile, I have to add this line to my Note class to make it work:
constructor(): this(UUID.randomUUID().toString(), "", NoteBadge()){}
However there I have NoteBadge() I'm creating an instance of NoteBadge manually, that's bad, I would like dagger did that.
I've tried sending a null value as parameter, but them I have a null NoteBadge at my MainActivity.
So do you have any idea how to fix that and make my dependency injection fully funcional? With no manual instance initializations?
EDIT -> Paste NoteComponent
#Component(modules = [NoteBadgeModule::class])
interface NoteComponent {
fun inject(activity: MainActivity)
}

add extension on Log in android (Kotlin)

I use this code to add extension for Log class android
fun Log.i2(msg:String):Unit{
Log.i("Test",msg)
}
when using in the activity
class MainActivity: AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
Log.i2("activity_main")
}
}
Log.i2 not found. What's wrong?

To achieve extension function in static class, you need to write extension of the companion object(refer this)
fun Log.Companion.i2(msg:String) {
...
}

You have created Extension function of Class Log.
Which is suppose to call by Instance of Class Log. You are trying to treat extension function as static and calling it by Class name. Which is not correct in the case

Currently, static extension methods in Kotlin is not supported without the companion object, because android.util.Log is a java class, so there is no companion object.
Instead, I recommend you to use a static function (package-level function, simply declared outside a class in a source code file):
fun logI2(msg: String) {
Log.i("Test", msg)
}
And just use it like this:
logI2("activity_main")