什么是Kotlin函数类型的Java等效项? [英] What is java equivalent of Kotlin's Function Types?

问题描述

我在Kotlin中有代码，在Java中有测试代码.由于Kotlin和Mockito不是最好的朋友，因此我没有将测试代码迁移到Kotlin.

I have code in Kotlin and test code in Java. Since Kotlin and Mockito aren't best friends, I haven't migrated test code to Kotlin.

在Kotlin中，我具有块类型的方法.例如:

In Kotlin I have methods with block types. For example:

open fun getProductInfo(resultListener: (List<Deal>)->Unit, errorListener: (Throwable)->Unit)
{
    ...
}

现在，我想在Java测试中将此方法存根.什么是Java类型的等效项?换句话说，我应该用什么代替下面的??? s:

Now I want to stub this method in Java tests. What's the java equivalent of the types? In other words, what should I write in place of ???s below:

doAnswer(invocation -> {
    ??? resultListener = (???) invocation.getArguments()[0];
    // call back resultListener
    return null;
}).when(api).getProductInfo(any(), any());

推荐答案

来自 行动中的科特林 本书:

Kotlin标准库定义了一系列接口，分别对应于不同数量的函数参数:Function0<R>(此函数不带参数)，Function1<P1, R>(此函数带一个参数)，依此类推.每个接口都定义一个调用方法，调用该接口将执行该功能.

The Kotlin standard library defines a series of interfaces, corresponding to different numbers of function arguments: Function0<R> (this function takes no arguments), Function1<P1, R> (this function takes one argument), and so on. Each interface defines a single invoke method, and calling it will execute the function.

在这种情况下，这两个函数都是Function1实例，因为它们是带有一个参数的函数:

In this case, these two functions are both Function1 instances, since they are functions that take one parameter:

Mockito.doAnswer(invocation -> {
    Function1<List<Deal>, Unit> resultListener =
            (Function1<List<Deal>, Unit>) invocation.getArguments()[0];
    Function1<Throwable, Unit> errorListener =
            (Function1<Throwable, Unit>) invocation.getArguments()[1];

    resultListener.invoke(new ArrayList<>());

    return null;
}).when(api).getProductInfo(any(), any());

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另一方面，您可以尝试 mockito-kotlin 和Mockito的内联版本，也可以在Kotlin中编写测试.

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On another note, you could try mockito-kotlin and the inline version of Mockito to write your tests in Kotlin as well.

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