Kotlin + Dagger-为ViewModel工厂注入地图 [英] Kotlin + Dagger - inject Map for ViewModel factory

问题描述

我正在将新的Architecture Components与Dagger2一起使用，我想使用Factory类注入ViewModel. Factory类本身是可注入的.当用Java定义Factory类时，这一切都很好，但是当我将其转换为Kotlin时，Dagger2不知道如何为构造函数生成Map，而在Java中则知道如何这样做.我认为区别在于，转换后，Factory类使用的是kotlin包中的Map，而不是java.util.Map包中的Map.如何获取Dagger2为Factory构造函数生成地图?

I'm using the new Architecture Components with Dagger2 and I would like to inject my ViewModels using a Factory class. The Factory class is itself injectable. This all works well when the Factory class is defined in Java, but when I convert it to Kotlin, Dagger2 does not know how to generate the Map for the constructor, while in Java it knows how to do so. I presume the difference is that, after conversion, the Factory class uses the Map from the kotlin package, as opposed to from java.util.Map package. How can I get Dagger2 to generate the map for the Factory constructor?

这是工厂课

@ActivityScope
class MainActivityViewModelFactory @Inject
constructor(private val creators: Map<Class<out ViewModel>, Provider<ViewModel>>) : ViewModelProvider.Factory {

    override fun <T : ViewModel> create(modelClass: Class<T>): T {
        var creator: Provider<out ViewModel>? = creators[modelClass]
        if (creator == null) {
            for ((key, value) in creators) {
                if (modelClass.isAssignableFrom(key)) {
                    creator = value
                    break
                }
            }
        }
        if (creator == null) {
            throw IllegalArgumentException("unknown model class " + modelClass)
        }
        try {
            return creator.get() as T
        } catch (e: Exception) {
            throw RuntimeException(e)
        }

    }
}

这是错误

Error:java.util.Map<java.lang.Class<? extends android.arch.lifecycle.ViewModel>,? extends javax.inject.Provider<android.arch.lifecycle.ViewModel>> cannot be provided without an @Provides-annotated method.

我尝试创建一个模块来提供地图，但这没有帮助.

I tried creating a module to provide the map, but that didn't help.

@ActivityScope
@Module
class MapModule {
    @Provides
    fun provideMap(): Map<Class<out ViewModel>, Provider<ViewModel>> = mutableMapOf()
}

推荐答案

我对您的ViewModelFactory代码做了一些修改:

I modified your ViewModelFactory code a bit:

@ActivityScope
class MainActivityViewModelFactory @Inject
constructor(private val creators: Map<Class<out ViewModel>, @JvmSuppressWildcards Provider<ViewModel>>) : ViewModelProvider.Factory {

    override fun <T : ViewModel> create(modelClass: Class<T>): T {
        var creator: Provider<out ViewModel>? = creators[modelClass]
        if (creator == null) {
            for ((key, value) in creators) {
                if (modelClass.isAssignableFrom(key)) {
                    creator = value
                    break
                }
            }
        }
        if (creator == null) {
            throw IllegalArgumentException("unknown model class " + modelClass)
        }
        try {
            return creator.get() as T
        } catch (e: Exception) {
            throw RuntimeException(e)
        }

    }
}

您可以尝试这个吗? 我添加了@JvmSuppressWildcards批注.

Can you try with this? I added @JvmSuppressWildcards annotation.

有关更多信息，您可以检查: https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.jvm/-jvm-suppress-wildcards/index.html

For more information you can check: https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.jvm/-jvm-suppress-wildcards/index.html

您可以从我的仓库中找到一个实时演示: https://github.com/savepopulation/dc-tracker

You can find a live demo from my repo: https://github.com/savepopulation/dc-tracker

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