无法"findViewById"；在科特林.得到错误“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

尝试类似的方法:

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

您也可以使用Kotlin Android Extensions.在此处上查看文档.
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:

• 在您的应用程序gradle.build中添加apply plugin: 'kotlin-android-extensions'
• 在您的班级中为import kotlinx.android.synthetic.main.<layout>.*添加导入，其中<layout>是布局的文件名.
• 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.

它如何工作?第一次调用recycler_view时，将完成对findViewById的调用并被缓存.

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

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