引用Kotlin中特定实例的方法 [英] Reference to method of a particular instance in Kotlin

问题描述

在Java 8中，我们可以引用Class实例的方法.这是一个例子

In Java 8 we can have a reference to a method of a Class' instance. Here's an example

Function1<Integer, Object> ref = a::getItem;

a是具有方法Object getItem(int i)的类Adapter的实例.

a is an instance of the class Adapter that has the method Object getItem(int i).

我们可以在Kotlin中做同样的事情吗?我尝试了相同的语法，但没有成功.到目前为止，我只能创建一个扩展方法引用，如下所示:

Can we do the same in Kotlin? I tried the same syntax without success. So far I was only able to create an extension method reference like so:

val ref: Adapter.(Int) -> Any = Adapter::getItem

但是在这里我仍然需要Adapter的实例来调用它.我看到的另一种替代方式是定义这样的lambda:

But here I still need an instance of an Adapter to invoke it. The other alterantive I see is defining a lambda like this:

val ref: (Int) -> Any = { a.getItem(it) }

推荐答案

从Kotlin 1.1开始，您可以使用

Since Kotlin 1.1, you can use bound callable references to do that:

val f = a::getItem

list.forEach(myObject::myMethod)

早期的Kotlin版本没有此功能，并且除了这些简单的案例.

Earlier Kotlin versions don't have this feature and require you to make a lambda every time except for these simple cases.

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