Inject Koin (dependency injection) in Java classes

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koin dependency injection android

I'm trying to replace Dagger 2 to Koin in my current project and I don't want to rewrite some classes in Kotlin to use it.

Is possible to inject with Koin in java classes?

In Kotlin is just

// Inject MyPresenter
val presenter : MyPresenter by inject()

Thanks

Yes it is Possible. Just sync project with this gradle file

implementation "org.koin:koin-java:$koin_version"

In your java class

 // Inject MyPresenter
 replace //val presenter : MyPresenter by inject()

   with  private Lazy<MyPresenter> presenter = inject(MyPresenter.class);

and get presenter method inside Java class like

presenter.getValue().sayHello() 

insert-koin.io · a smart Kotlin dependency injection framework, In this tutorial, you'll get to know Koin, one of the most popular new frameworks In order to inject dependencies in other class types, you must do it through the databaseBuilder(androidContext(), AppDatabase::class.java,  Dependency injection (DI) is the concept in which objects get other required objects from outside. DI can be implemented in any programming language. The general concept behind dependency injection is called Inversion of Control. A Java class has a dependency on another class, if it uses an instance of this class.

A class or file can either have .kt extension means Kotlin, or have .java extension means Java. You can't write a file or class in both the languages simultaneously.

But your Java and Kotlin files can talk with each other, i.e you can a Java class with a variable and access that variable in your Kotlin file or vice-versa.

So you can inject a Kotlin class reference and use that in your Java class and Vice-versa.

This might help: https://kotlinlang.org/docs/tutorials/mixing-java-kotlin-intellij.html

I hope that clears the doubt.

Dependency Injection With Koin, Suppose we have two classes, the Class A and Class B, when the class Koin is a pragmatic lightweight dependency injection framework for Kotlin are going to declare all the dependencies that will be injected in another  Koin is a pragmatic lightweight dependency injection framework for Kotlin developers to whom we will give the responsibility to instantiate the different objects of our application.

It is, make sure you import in gradle the koin for java library and use above answers.

Gradle:

implementation "org.koin:koin-java:2.0.1"

Dependency Injection with Koin - The Startup, Dependency Injection, or DI, is a design pattern/technique as old as time itsel. As the name says we'll inject that dependency somehow into the object. Let's say you have a repository class in your app that you can use to access Dagger2 is written in Java, Koin is purely kotlin so it looks more natural  Classes using field injection tend to become harder to maintain When you use the field injection pattern, and want to further add dependencies to your class you only need to make a field, slap an @Autowired or @Inject annotation on it and you’re good to go.

Android Dependency Injection with Koin, Koin is a lightweight dependency injection framework, that uses Kotlin's DSLs to function), you get access to functions like get, inject, getKoin, viewModel, etc. single or factory dependency definitions as java classes inside java packages. One limitation when using Koin is that you can only inject dependencies in Activity classes out of the box. In order to inject dependencies in other class types, you must do it through the corresponding constructors. To solve this problem, Koin allows classes to conform to the KoinComponent interface, so that injections are possible on non-Activity classes. You will see an example of this later on. Getting Started

Koin - Simple Android DI, Here our SomeHelper class will also need the @Inject constructor, but inside of a Koin module so that it can be provided for injection: Java. I have a piece of code which I want to refactor into a dependency injection style. It currently looks like this: class MyService { public void A(Account account, String someparam1, int someparam2) { AccountHandler myHandler = new AccountHandler(account); // Do something with AccountHandler

A brief look at Koin on Android, Many experienced Java Developers are familiar with Dagger, some may have Koin is a lightweight dependency injection framework written purely in Kotlin that class MainActivity : AppCompatActivity() { // Lazy injected  Let’s have a look at the more familiar pattern of injecting Java objects/beans like services into activities. DI with Dagger. Dagger is a light-weight dependency injection library that comes with support for Java’s JSR-330 annotations like @Inject or @Singleton. The creation of object instances that need to be injected at runtime are

Comments
  • I am pretty sure that this is possible. Both Java and Kotlin run on the JVM and thus should be interoperable.
  • Yeah, they work. But I would like to know how can I access inject using Koin framework.
  • This might help you...github.com/Ekito/koin/issues/81
  • Excellent, @keshavAggarwal This is what I need gist.github.com/fredy-mederos/b74e8c2f2ca2f0f5d5910bcb694cbdbf
  • Hey, Is your problem solved?
  • Hey @pawan soni, could you clarify which imports you are using for inject and Lazy? is it import static org.koin.core.KoinComponentKt.inject; and import kotlin.Lazy; ?
  • kotlin.Lazy and org.koin.java.KoinJavaComponent.inject