相当于Java的Kotlin？扩展`

Question

我试图将模块类(Dagger)转换为kotlin文件，但在构建kotlin转换代码时却面临这个问题。

@Binds方法的参数类型必须分配给返回类型

这就是我想要解决的问题。

@Binds
@IntoMap
@ClassKey(EnterEmailFragment::class)
abstract fun bindsEnterEmailInjector(injector: EnterEmailInjector): ScreenInjector<in Fragment, out Any>

Java代码：(Java代码运行良好！)

@Binds
@IntoMap
@ClassKey(EnterEmailFragment.class)
abstract ScreenInjector<? extends Fragment, ? extends Object> bindsEnterEmailInjector(EnterEmailInjector injector);

这就是.class文件的样子

public abstract class com.gojek.driver.ulysses.email.di.EmailScreenFactoryModule {
  public static final com.gojek.driver.ulysses.email.di.EmailScreenFactoryModule$Companion Companion;

  public abstract com.gojek.driver.base.ScreenInjector<androidx.fragment.app.Fragment, java.lang.Object> bindsEnterEmailInjector(com.gojek.driver.ulysses.email.di.EnterEmailInjector);

  public com.gojek.driver.ulysses.email.di.EmailScreenFactoryModule();
    Code:
       0: aload_0
       1: invokespecial #16                 // Method java/lang/Object."<init>":()V
       4: return

  static {};
    Code:
       0: new           #42                 // class com/gojek/driver/ulysses/email/di/EmailScreenFactoryModule$Companion
       3: dup
       4: aconst_null
       5: invokespecial #49                 // Method com/gojek/driver/ulysses/email/di/EmailScreenFactoryModule$Companion."<init>":(Lkotlin/jvm/internal/DefaultConstructorMarker;)V
       8: putstatic     #40                 // Field Companion:Lcom/gojek/driver/ulysses/email/di/EmailScreenFactoryModule$Companion;
      11: return

  public static final com.gojek.driver.ulysses.email.di.EnterEmailInjector providesEnterEmailInjector(com.gojek.driver.ulysses.driver.DriverProfileUsecase);
    Code:
       0: getstatic     #40                 // Field Companion:Lcom/gojek/driver/ulysses/email/di/EmailScreenFactoryModule$Companion;
       3: aload_0
       4: invokevirtual #44                 // Method com/gojek/driver/ulysses/email/di/EmailScreenFactoryModule$Companion.providesEnterEmailInjector:(Lcom/gojek/driver/ulysses/driver/DriverProfileUsecase;)Lcom/gojek/driver/ulysses/email/di/EnterEmailInjector;
       7: areturn
}

不太确定我在这里错过了什么。

Answer 1

这实际上是一个已知的问题，发生在Kotlin的投影类型上。这在匕首的github问题中有报道。

为了解决这个问题，github问题和这文章建议使用@JvmSuppressWildcards来抑制编译器创建的警告。

@Binds
@IntoMap
@ClassKey(EnterEmailFragment::class)
abstract fun bindsEnterEmailInjector(injector: EnterEmailInjector)
    : ScreenInjector<out @JvmSuppressWildcards Fragment, out @JvmSuppressWildcards Any>