无法“findViewById"在科特林.获取错误“类型推断失败" [英] Not able to "findViewById" in Kotlin. Getting error "Type inference failed"

问题描述

当我尝试通过 id 查找 RecycleView 时出现以下错误.

I am getting the following error when I try to find a RecycleView by id.

错误:-类型推断失败:没有足够的信息来推断参数 T

Error:- Type inference failed: Not enough information to infer parameter T

代码:

class FirstRecycleViewExample : AppCompatActivity() {
    val data = arrayListOf<String>()
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.first_recycleview)

        val recycler_view =  findViewById(R.id.recycler_view) as RecyclerView ///IN THIS LINE I AM GETTING THE ERROR

        data.add("First Data")
        data.add("Second Data")
        data.add("Third Data")
        data.add("Forth Data")
        data.add("Fifth Data")

        //creating our adapter
        val adapter = CustomRecycleAdapter(data)

        //now adding the adapter to recyclerview
        recycler_view.adapter = adapter
    }
}

推荐答案

尝试类似:

val recyclerView = findViewById<RecyclerView>(R.id.recycler_view)

您也可以为此使用 Kotlin Android 扩展.在此处查看文档.
有了它，您可以直接在代码中调用 recycler_view.

You can use Kotlin Android Extensions too for that. Check the doc here.
With it, you can call recycler_view directly in your code.

Kotlin Android 扩展:

• 在你的应用 gradle.build 中添加 apply plugin: 'kotlin-android-extensions'
• 在您的课程中为 import kotlinx.android.synthetic.main..* 添加 import，其中 是您的布局的文件名.
• 就是这样，您可以直接在代码中调用 recycler_view.

• In your app gradle.build add apply plugin: 'kotlin-android-extensions'
• In your class add import for import kotlinx.android.synthetic.main.<layout>.* where <layout> is the filename of your layout.
• That's it, you can call recycler_view directly in your code.

它是如何工作的?第一次调用 recycler_view 时，会调用 findViewById 并缓存.

How does it work? The first time that you call recycler_view, a call to findViewById is done and cached.

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