为什么不能匕首处理这些kotlin仿制药？

我和Dagger有一些奇怪的kotlin泛型问题,我有点固定,但解决方案并不合理.

这是匕首类:

@Module class P5Module {
    @Provides fun pool(): RecyclerView.RecycledViewPool = RecyclerView.RecycledViewPool()
    @Provides
    fun adapters(fusion: P5FusionAdapter, personas: P5ListAdapter, skills: P5SkillsAdapter, info: InfoAdapter)
            : List = listOf(fusion, personas, skills, info)
}

@ActivityScope
@Subcomponent(modules = arrayOf(P5Module::class)) interface P5Component {
    fun adapter(): PageableAdapter
}

interface Pageable {
    fun manager(ctx: Context): LayoutManager
    fun attach()
    fun adapter(): Adapter<*>
}

class PageableAdapter
@Inject constructor(val pageables: List, val pool: RecyclerView.RecycledViewPool) :PagerAdapter()

当我构建时,我在顶级组件中得到了这个kapt错误:

e: C:\Users\daykm\StudioProjects\P5Executioner\app\build\tmp\kapt3\stubs\appDebug\com\daykm\p5executioner\AppComponent.java:17: error: [com.daykm.p5executioner.main.P5Component.adapter()] java.util.List cannot be provided without an @Provides-annotated method.
e: 

e: public abstract interface AppComponent {
e:                 ^
e:       java.util.List is injected at
e:           com.daykm.p5executioner.view.PageableAdapter.(pageables, …)
e:       com.daykm.p5executioner.view.PageableAdapter is provided at
e:           com.daykm.p5executioner.main.P5Component.adapter()
e: java.lang.IllegalStateException: failed to analyze: org.jetbrains.kotlin.kapt3.diagnostic.KaptError: Error while annotation processing

我看了一下生成的存根:

@javax.inject.Inject()
public PageableAdapter(@org.jetbrains.annotations.NotNull()
java.util.List pageables, @org.jetbrains.annotations.NotNull()
android.support.v7.widget.RecyclerView.RecycledViewPool pool) {
    super();
}

@org.jetbrains.annotations.NotNull()
@dagger.Provides()
public final java.util.List adapters(@org.jetbrains.annotations.NotNull()

显然不匹配,因为当我像这样修改匕首类时:

@Module class P5Module {
    @Provides fun pool(): RecyclerView.RecycledViewPool = RecyclerView.RecycledViewPool()
    @Provides
    fun adapters(fusion: P5FusionAdapter, personas: P5ListAdapter, skills: P5SkillsAdapter, info: InfoAdapter)
            : List<*> = listOf(fusion, personas, skills, info)
}

@ActivityScope
@Subcomponent(modules = arrayOf(P5Module::class)) interface P5Component {
    fun adapter(): PageableAdapter
}

interface Pageable {
    fun manager(ctx: Context): LayoutManager
    fun attach()
    fun adapter(): Adapter<*>
}

class PageableAdapter
@Inject constructor(val pageables: List<*>, val pool: RecyclerView.RecycledViewPool) :PagerAdapter()

问题消失了.我是否因为协方差和逆变而陷入一些奇怪的翻译问题？我宁愿不强迫下游演员.

Kotlin 默认List转换为Java中的协方差List.匕首不喜欢那样.

要解决此问题,您可以切换到MutableList哪个是不变的,也可以写入List<@JvmSuppressWildcards E>.