Koin how to inject outside of Android activity / appcompatactivity

**[Koin][1]** is a new, lightweight library for DI and can be used in Android as well as in standalone kotlin apps.

Usually you inject dependencies like this:

class SplashScreenActivity : Activity() {

val sampleClass : SampleClass by inject()

override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
}
}

with the `inject()` method.

But what about injecting stuff in places where Activity context is not available i.e. **outside of an Activity**?


[1]:

[To see links please register here]

There is the `KoinComponent` which comes to the rescue. In any class you can simply:

class SampleClass : KoinComponent {

val a : A? by inject()
val b : B? by inject()
}

Extending `KoinComponent` gives you access to `inject()` method.

Remember that usually it's enough to inject stuff the usual way:

class SampleClass(val a : A?, val b: B?)

Koin provides a solution for this using the `KoinComponent` interface. For example, if you need to get some dependencies in your repository then you can simply implement the KoinComponent interface. It gives you access to various Koin features such as `get()` and `inject()`. Use KoinComponent only when you can't rewrite the constructor to accept dependencies as constructor parameters.

```
class MyRepository: Repository(), KoinComponent {
private val myService by inject<MyService>()
}
```

**Constructor injection is better than this approach.**

For example, the same thing can be achieved by:

```
class MyRepository(private val service: MyService): Repository() {
...
}
```
And you can add the definition for instantiating this class in a koin module:

```
val serviceModule = module {
...

factory { MyService() }
}
val repositoryModule = module {
...

factory { MyRepository(get<MyService>()) }
}
```

If you don't want to implement any interfaces then just take a look at how [`KoinComponent.inject()`][1] is implemented and do something similar yourself:

val foo by lazy { KoinPlatformTools.defaultContext().get().get<FooClass>() }

[1]:

[To see links please register here]