如何在 Fragment 中使用 Spinner？

我在里面添加override fun onCreateView了这段代码：

 val array = arrayOf("Option 1", "Option 2", "Option 3")
    
            spinner = view?.findViewById<Spinner>(R.id.spinner)
            spinner?.adapter = ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, array)
    
            spinner?.onItemSelectedListener = object : AdapterView.OnItemSelectedListener{
                override fun onItemSelected(p0: AdapterView<*>?, p1: View?, p2: Int, p3: Long) {
                    //  result?.text = array.get(p2)
    
                    when(p2) {
                       // 0 -> result?.text = array.get(0)
                      //  1 -> result?.text = array.get(1)
                      //  2 -> result?.text = array.get(2)
                    }
                }
    
    
                override fun onNothingSelected(p0: AdapterView<*>?) {
                    // result?.text = array.get(0)
                }
    
            }

ArrayAdapter红色下划线

一切MainActivity正常。请告诉我如何制作它，以便片段内的所有内容也正常工作。

xml片段：

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    tools:context=".presentation.ExchangeRateFragment">

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <androidx.constraintlayout.widget.ConstraintLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <androidx.appcompat.widget.AppCompatSpinner
                android:id="@+id/spinner"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                tools:ignore="MissingConstraints" />

            <LinearLayout
                xmlns:android="http://schemas.android.com/apk/res/android"
                xmlns:tools="http://schemas.android.com/tools"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:orientation="horizontal"
                tools:ignore="MissingConstraints,RedundantNamespace">

            <androidx.appcompat.widget.AppCompatButton
                android:id="@+id/sortAlphabetAscending"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                app:layout_constraintTop_toTopOf="parent"
                android:layout_weight="1"
                android:layout_marginTop = "30dp"
                android:padding="20dp"
                android:background="@color/black"
                android:textColor="@color/white"
                android:text="@string/sortASC" />

            <androidx.appcompat.widget.AppCompatButton
                android:id="@+id/sortAlphabetDescending"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                app:layout_constraintTop_toTopOf="parent"
                android:layout_weight="1"
                android:layout_marginTop = "30dp"
                android:padding="20dp"
                android:background="@color/black"
                android:textColor="@color/white"
                android:text="@string/sortDESC" />

                <androidx.appcompat.widget.AppCompatButton
                    android:id="@+id/sortNumberAscending"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    app:layout_constraintTop_toTopOf="parent"
                    android:layout_weight="1"
                    android:layout_marginTop = "30dp"
                    android:padding="20dp"
                    android:background="@color/black"
                    android:textColor="@color/white"
                    android:text="@string/sortNumberASC" />

                <androidx.appcompat.widget.AppCompatButton
                    android:id="@+id/sortNumberDescending"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    app:layout_constraintTop_toTopOf="parent"
                    android:layout_weight="1"
                    android:layout_marginTop = "30dp"
                    android:padding="20dp"
                    android:background="@color/black"
                    android:textColor="@color/white"
                    android:text="@string/sortNumberDESC" />


            </LinearLayout>

            <androidx.recyclerview.widget.RecyclerView
                android:id="@+id/exchangeRateRV"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                app:layout_constraintTop_toTopOf="parent"
                app:layout_constraintStart_toStartOf="parent"
                android:layout_marginTop="90dp"
                app:layout_constraintTop_toBottomOf="@id/spinner"/>

        </androidx.constraintlayout.widget.ConstraintLayout>

    </FrameLayout>

</layout>

方法onCreateView：

    private var binding: FragmentExchangeRateBinding? = null
    private var exchangeRateAdapter : ExchangeRateAdapter? = null
    private val exchangeRateViewModel : ExchangeRateViewModel? by viewModel()
    private val favouriteViewModel: FavouriteViewModel by viewModel()
    private var spinner : Spinner? = null

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

        binding = DataBindingUtil.inflate(inflater, R.layout.fragment_exchange_rate, container, false)

        initRecyclerExchangeRate()
        loadExchangeRate()

        binding?.sortAlphabetAscending?.setOnClickListener {

            exchangeRateViewModel?.getSortCurrencyAlphabetAscending?.observe(
                viewLifecycleOwner, Observer {
                    exchangeRateAdapter?.setList(it)
                    exchangeRateAdapter?.notifyDataSetChanged()
                }
            )
        }

        binding?.sortAlphabetDescending?.setOnClickListener {

            exchangeRateViewModel?.getSortCurrencyAlphabetDescending?.observe(
                viewLifecycleOwner, Observer {
                    exchangeRateAdapter?.setList(it)
                    exchangeRateAdapter?.notifyDataSetChanged()
                }
            )

        }

        binding?.sortNumberAscending?.setOnClickListener {

            exchangeRateViewModel?.getSortCurrencyNumberAscending?.observe(
                viewLifecycleOwner, Observer {
                    exchangeRateAdapter?.setList(it)
                    exchangeRateAdapter?.notifyDataSetChanged()
                }
            )

        }

        binding?.sortNumberDescending?.setOnClickListener {

            exchangeRateViewModel?.getSortCurrencyNumberDescending?.observe(
                viewLifecycleOwner, Observer {
                    exchangeRateAdapter?.setList(it)
                    exchangeRateAdapter?.notifyDataSetChanged()
                }
            )

        }

        val array = arrayOf("Option 1", "Option 2", "Option 3")

        val rootView = inflater.inflate(R.layout.fragment_exchange_rate, container, false)
        spinner = rootView.findViewById<Spinner>(R.id.spinner)

      //  spinner = view?.findViewById<Spinner>(R.id.spinner)
        
        spinner?.adapter =  ArrayAdapter<String>(requireContext(), android.R.layout.simple_list_item_1, array)
        
       // spinner?.adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item)

/*        ArrayAdapter.createFromResource(
            activity?.applicationContext!!,
            R.array.currency_array,
            android.R.layout.simple_spinner_item
        ).also { adapter ->
            // Specify the layout to use when the list of choices appears
            adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item)
            // Apply the adapter to the spinner
            spinner?.adapter = adapter
        }*/

        spinner?.onItemSelectedListener = object : AdapterView.OnItemSelectedListener{
            override fun onItemSelected(p0: AdapterView<*>?, p1: View?, p2: Int, p3: Long) {
                //  result?.text = array.get(p2)

                when(p2) {
                   // 0 -> result?.text = array.get(0)
                  //  1 -> result?.text = array.get(1)
                  //  2 -> result?.text = array.get(2)
                }
            }


            override fun onNothingSelected(p0: AdapterView<*>?) {
                // result?.text = array.get(0)
            }

        }

        return binding?.root
    }