Kotlin等同于Java`？延伸`

问题描述

我正在尝试将模块类（匕首）转换为kotlin文件，但是在尝试构建kotlin转换后的代码时会遇到此问题。

@Binds方法的参数类型必须可分配给返回类型

这是我要解决的问题。

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

Java代码：（Java代码正常工作！）

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

这是.class文件的外观

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
}

不太确定我在这里缺少什么。

解决方法

这实际上是一个已知问题，发生在Kotlin的突出类型上。在匕首的github issue中有报道。

作为解决该问题的变通办法，github问题和this文章建议使用@JvmSuppressWildcards来抑制由编译器创建的警告。

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