Question

我在RecyclerView中遇到Fragment的问题。在MainActivity中，我有一个TabLayout和一个ViewPager。我想在第一个标签中显示RecyclerView，但仍然出现以下错误：

E / RecyclerView：未连接适配器；跳过布局

我尝试将回收站适配器初始化移至OnViewCreated，但没有结果。

这是我的片段代码：

override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {

        listOfGreetings?.add(0, GreetingModel("Greeting 1", R.drawable.ic_launcher_background))
        listOfGreetings?.add(1, GreetingModel("Greeting 2", R.drawable.greeting_1))
        listOfGreetings?.add(2, GreetingModel("Greeting 3", R.drawable.greeting_1))
        listOfGreetings?.add(3, GreetingModel("Greeting 4", R.drawable.greeting_1))
        listOfGreetings?.add(4, GreetingModel("Greeting 5", R.drawable.greeting_1))
        listOfGreetings?.add(5, GreetingModel("Greeting 6", R.drawable.greeting_1))
        listOfGreetings?.add(6, GreetingModel("Greeting 7", R.drawable.greeting_1))
        listOfGreetings?.add(7, GreetingModel("Greeting 8", R.drawable.greeting_1))


        val recyclerView = container?.findViewById<RecyclerView>(R.id.recyclerView)
        val manager = LinearLayoutManager(activity)



        recyclerView?.setHasFixedSize(true)
        recyclerView?.layoutManager = manager



        recyclerView?.adapter = greetingAdapter

        return inflater.inflate(R.layout.fragment_category, container, false)

    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        greetingAdapter = GreetingAdapter(activity!!, listOfGreetings!!.toList())
    }

这是XML：

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
             xmlns:tools="http://schemas.android.com/tools"
             android:layout_width="match_parent"
             android:layout_height="match_parent" xmlns:app="http://schemas.android.com/apk/res-auto"
             tools:context=".CategoryFragment">

    <androidx.recyclerview.widget.RecyclerView
            android:id="@+id/recyclerView"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_marginTop="3dp"
            />

</FrameLayout>

Answer 1

您看到此错误消息是因为?.中的安全调用recyclerView?.adapter = greetingAdapter将返回null，所以它不会被执行，因为您是在视图{{1 }}，因此可以解决该问题：创建一个具有膨胀视图值的变量，然后使用它从中获取视图并返回它，就像这样：

inflater.inflate(R.layout.fragment_category, container, false)

此外，您在代码中过度使用了安全呼叫运算符override fun onCreateView( inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle? ): View? { listOfGreetings?.add(0, GreetingModel("Greeting 1", R.drawable.ic_launcher_background)) listOfGreetings?.add(1, GreetingModel("Greeting 2", R.drawable.greeting_1)) listOfGreetings?.add(2, GreetingModel("Greeting 3", R.drawable.greeting_1)) listOfGreetings?.add(3, GreetingModel("Greeting 4", R.drawable.greeting_1)) listOfGreetings?.add(4, GreetingModel("Greeting 5", R.drawable.greeting_1)) listOfGreetings?.add(5, GreetingModel("Greeting 6", R.drawable.greeting_1)) listOfGreetings?.add(6, GreetingModel("Greeting 7", R.drawable.greeting_1)) listOfGreetings?.add(7, GreetingModel("Greeting 8", R.drawable.greeting_1)) //This varaible will holds a reference to the inflated view. val view = inflater.inflate(R.layout.fragment_category, container, false) //Get the recyclerView from the inflated view. val recyclerView = view.findViewById<RecyclerView>(R.id.recyclerView) val manager = LinearLayoutManager(activity) //No need to the safe call ?. here because recyclerView won't be null. recyclerView.setHasFixedSize(true) recyclerView.layoutManager = manager recyclerView.adapter = greetingAdapter return view }。 ?.可以变得更加简单，您可以在安全调用中将listGreetings用于对象apply()，

listGreeting

这将检查如果listOfGreetings?.apply { add(0, GreetingModel("Greeting 1", R.drawable.ic_launcher_background)) add(1, GreetingModel("Greeting 2", R.drawable.greeting_1)) add(2, GreetingModel("Greeting 3", R.drawable.greeting_1)) add(3, GreetingModel("Greeting 4", R.drawable.greeting_1)) add(4, GreetingModel("Greeting 5", R.drawable.greeting_1)) add(5, GreetingModel("Greeting 6", R.drawable.greeting_1)) add(6, GreetingModel("Greeting 7", R.drawable.greeting_1)) add(7, GreetingModel("Greeting 8", R.drawable.greeting_1)) }不等于null，将执行listGreetings块中的代码：

apply

E / RecyclerView：未连接适配器，跳过布局

1 个答案: