将lambda存储在Kotlin中的变量中 [英] Store lambda in a variable in kotlin

问题描述

我开始使用Kotlin在Android中进行开发，但是lambdas出现问题.我有一个函数可以在我的视图中设置一个侦听器，如下所示:

I'm starting developing in Android with kotlin and I have a problem with lambdas. I have a function to set a listener in my view, this looks like this:

fun setListener(listener: () -> Unit) {
}

问题是作为lambda传递的代码将不会在setListener函数中执行，它将在代码的另一部分(特别是在选择微调器的项目时)执行，因此我必须保存"或将此lambda存储"到变量/属性中，以便我可以在需要时执行它.关于如何做的任何想法?

The problem is that the code passed as lambda won't be executed in setListener function, it will be executed in another part of my code (specifically when an item of a spinner is selected) so I have to "save" or "store" this lambda into a variable/property so that I'm able to execute it when needed. Any idea about how to do it?

我已经做到了:

private var listener: (() -> Unit)? = null

fun setListener(listener: () -> Unit) {
    this.listener = listener
}

有更好的方法吗?谢谢

推荐答案

以下是您的操作方法:

class Foo {
    private var listener: () -> Unit = {}
    fun setListener(listener: () -> Unit) {
        this.listener = listener
    }
}

但是，在Kotlin中不建议手动编写二传手.相反，您可以将自己的媒体资源公开:

However, manually writing setters is discouraged in Kotlin. Instead, you can just make your property public:

class Foo {
    var listener: () -> Unit = {}
}

作为参考，这里是关于属性的文档，其中包含许多示例.

For reference, here are the docs about properties with lots of examples.

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