Inject context with Hilt: this field leaks a context object

Question

I'm using Hilt to inject context and other dependencies into my HomeViewModel class; Everything is working properly but I'm getting this warning. How can I prevent from leakings?

This is my HomeFragment (where I inject and use the HomeViewModel class):

@AndroidEntryPoint
class HomeFragment : Fragment() {

private val viewModel: HomeViewModel by viewModels()

....

}

This is the warning:

class HomeViewModel @ViewModelInject constructor(
    @ApplicationContext val context: Context,
    private val locationAPI: LocationAPI,
    private val imagesAPI: ImagesAPI
) :
    ViewModel() {
...
}

I'm using:

//Hilt DI
implementation "com.google.dagger:hilt-android:2.30.1-alpha"
kapt "com.google.dagger:hilt-android-compiler:2.30.1-alpha"
implementation "androidx.hilt:hilt-lifecycle-viewmodel:1.0.0-alpha02"
kapt "androidx.hilt:hilt-compiler:1.0.0-alpha02"

Thanks!

-- Edited, as suggested, after the first given answer:

The Home Fragment now is:

@HiltViewModel
class DetailsViewModel @Inject constructor(
    @ApplicationContext val context: Context,
    private val locationDetailsAPI: LocationAPI) :
    ViewModel() {
...

}

Dependencies updated to:

//Hilt DI
implementation "com.google.dagger:hilt-android:2.31-alpha"
kapt "com.google.dagger:hilt-android-compiler:2.30.1-alpha"
implementation "androidx.hilt:hilt-lifecycle-viewmodel:1.0.0-alpha03"
kapt "androidx.hilt:hilt-compiler:1.0.0-alpha03"

And I'm still getting this leaking error.

Any ideias?

Answer 1

I don't get this warning, and I inject a context the same way.

Try updating to 2.31.2-alpha for hilt and 1.0.0-alpha03 for hilt-androidx

There are a few breaking changes. You will need to annotate your view models with @HiltViewModel, use @Inject instead of @ViewModelInject. And you will need to replace any references to ApplicationComponent with SingletonComponent.

Answer 2

After I faced that warning

I decided to profile memory to be guaranteed that the approach causes a memory leak, but what I found is quite interesting

yeah, there is no leak it's just a warning so don't care about it anymore, happy coding ;)

Answer 3

Your Kotlin plugin version is 1.4.30-release-Studio4.1-1?

If so, downgrade kotlin plugin version.

In 1.4.30-release-Studio4.1-1 version,

if viewmodel has context as instance variable, it causes warning.

Answer 4

Inject application instead:

@Inject constructor(private val application: Application)

Then you can get the app context like this:

application.applicationContext

Answer 5

I had the same problem after updating Hilt dependencies.

It's right to use @HiltViewModel with @Inject before the constructor.

Regarding the leak due to the Context, just remove it from the ViewModel constructor, and pass the Context as method parameter of your functions, like this:

@HiltViewModel
class HomeViewModel @Inject constructor(
    private val locationDetailsAPI: LocationAPI,
    private val imagesAPI: ImagesAPI
) : ViewModel() { 

    fun getImages(context: Context) {
        // do something
    }
}

Answer 6

it should be safe here, There isn't really a leak here in the context constructor, it is just the lint check doesn't know that is the application context, and not some other context. and I think I think it'd be safe to suppress that warning too. to inspect the memory memory usage with Memory Profiler, read this documentation: https://developer.android.com/studio/profile/memory-profiler