Inject Koin in Java classes

Injecting Koin in Java Classes

Koin is a powerful dependency injection framework for Kotlin that can also be used with Java. This article will guide you through the process of injecting Koin into your Java classes.

Setting up Koin

1. Add Koin Dependency

First, add the Koin dependency to your project’s build.gradle file:

implementation("org.koin.core:koin-android:3.2.0")

2. Initialize Koin

In your application’s entry point, initialize Koin:

import org.koin.android.ext.koin.androidContext
import org.koin.core.context.startKoin

class MyApplication : Application() {
    override fun onCreate() {
        super.onCreate()
        startKoin {
            androidContext(this@MyApplication)
            modules(appModule)
        }
    }
}

Here, appModule is the module containing your dependencies definitions. We’ll define this module later.

Defining Dependencies in Modules

Create a separate Kotlin file for your module definitions. This example uses the appModule defined above:

import org.koin.dsl.module

val appModule = module {
    single { MyRepository() } // Define a single instance of MyRepository
}

This module defines a single instance of MyRepository using the single function. Koin will create and manage this instance automatically.

Injecting Dependencies in Java Classes

1. Add Koin’s Java Support

Make sure you have the Koin Java support dependency:

implementation("org.koin.core:koin-core-ext:3.2.0")

2. Use the Koin DSL

Import the Koin DSL and use the inject function within your Java class:

import org.koin.core.component.KoinComponent
import org.koin.core.component.inject

public class MyJavaClass {
    private val repository: MyRepository by inject()

    public void doSomething() {
        // Use repository instance
        repository.fetchData() 
    }
}

The inject function provides a delegated property to access the injected instance of MyRepository.

Benefits of Using Koin with Java

• Simplified Dependency Management: Koin handles dependency creation and injection, reducing boilerplate code.
• Testability: Koin makes unit testing easier by providing mock implementations and control over dependencies.
• Modular Architecture: Koin promotes a modular approach, allowing for cleaner code and better maintainability.

Conclusion

Koin offers a seamless way to manage dependencies in your Java classes, providing a powerful and flexible solution for dependency injection. By following these steps, you can effectively integrate Koin into your Java projects and benefit from its many advantages.