与Kotlin的Dagger 2多重绑定 [英] Dagger 2 multibindings with Kotlin

问题描述

我的Dagger 2模块中有以下代码段

I have the following snippet in my dagger 2 module

@Singleton
@Provides
@ElementsIntoSet
fun providesQueries(foo: Foo): Set<Foo>{
    val queries = LinkedHashSet<Foo>()
    queries.add(foo)
    return queries
}

我试图以这种方式注入

@Inject lateinit var foo: Set<Foo>

但是dagger显示了一个错误，该错误表明Dagger无法在没有@Provides或@Produces方法的情况下提供java.util.Set.

But dagger shows an error which says that Dagger cannot provides java.util.Set without @Provides or @Produces method.

我在Java中也做过同样的事情，而且效果很好.有人知道为什么会失败吗?

I did the same in java and it worked. Does somebody know why is it failing?

推荐答案

如Kotlin中所述

As it described in the Kotlin reference

要使Kotlin API在Java中工作，我们将Box<Super>生成为 Box<? extends Super>用于协变定义的Box(或Foo<? super Bar>用于 相反地​​定义为Foo).

To make Kotlin APIs work in Java we generate Box<Super> as Box<? extends Super> for covariantly defined Box (or Foo<? super Bar> for contravariantly defined Foo) when it appears as a parameter.

您可以使用@JvmSuppressWildcards来避免它，如下所示:

You can use @JvmSuppressWildcards for avoiding it, just as following:

@Inject lateinit var foo: Set<@JvmSuppressWildcards Foo>

这篇关于与Kotlin的Dagger 2多重绑定的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！