如何在ListView中显示SQLite表

Question

我已经创建了一个包含汽车信息（品牌/型号/里程/等）的虚拟表，我想在用户点击搜索按钮后将其显示在ListView中，但是到目前为止无法使代码正常工作

我创建了一个CursorAdapter尝试将信息转换为ListView，但我尝试过的任何方法都没有用。

搜索片段

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

    // Inflate the layout for this fragment
    val view = inflater?.inflate(R.layout.fragment_home,
        container, false)

    val spinner: Spinner = view.findViewById(R.id.spinner)
    // ArrayAdapter using the string array and a default spinner layout
    ArrayAdapter.createFromResource(
        this.context,
        R.array.vehicle_types,
        android.R.layout.simple_spinner_item
    ).also { adapter ->
        // 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
    }

    val btnSearch: Button = view.findViewById(R.id.btn_search)
    val lv: ListView = view.findViewById<ListView>(R.id.lv_search)
    btnSearch.setOnClickListener {
        val dbTable = DatabaseTable(this.context)
        val cursor = dbTable.getAllCars()
        val carCursorAdapter = CarCursorAdapter(this.context, cursor)
        lv.adapter = carCursorAdapter
    }





    return view
}

}

CursorAdapter

class CarCursorAdapter(context:Context?, cursor:Cursor): CursorAdapter(context, cursor, true) {
override fun newView(context: Context?, cursor: Cursor?, parent: ViewGroup?): View {
    return LayoutInflater.from(context).inflate(R.layout.item_car, parent, false)
}

override fun bindView(view: View?, context: Context?, cursor: Cursor?) {
    //Find fields to populate in template
    val tvMake = view?.findViewById<TextView>(R.id.tv_make)
    val tvModel = view?.findViewById<TextView>(R.id.tv_model)
    val tvYear = view?.findViewById<TextView>(R.id.tv_year)
    val tvMileage = view?.findViewById<TextView>(R.id.tv_mileage)
    val tvPrice = view?.findViewById<TextView>(R.id.tv_price)

    //Extract properties from cursor
    val make = cursor?.getString(cursor.getColumnIndexOrThrow("make"))
    val model = cursor?.getString(cursor.getColumnIndexOrThrow("model"))
    val year = cursor?.getString(cursor.getColumnIndexOrThrow("year"))
    val mileage = cursor?.getString(cursor.getColumnIndexOrThrow("mileage"))
    val price = cursor?.getString(cursor.getColumnIndexOrThrow("price"))

    //Populate fields with extracted properties
    if (tvMake != null) {
        tvMake.setText(make)
    }

    if (tvModel != null) {
        tvModel.setText(model)
    }

    if (tvYear != null) {
        tvYear.setText(year)
    }

    if (tvMileage != null) {
        tvMileage.setText(mileage)
    }

    if (tvPrice != null) {
        tvPrice.setText(price)
    }


}

}

数据库表

private const val TAG = "CarDatabase"

//Columns in the table
const val COL_TYPE = "TYPE"
const val COL_MAKE = "MAKE"
const val COL_MODEL = "MODEL"
const val COL_YEAR = "YEAR"
const val COL_MILEAGE = "MILEAGE"
const val COL_PRICE = "PRICE"

private const val DATABASE_NAME = "CARS"
private const val FTS_VIRTUAL_TABLE = "FTS"
private const val DATABASE_VERSION = 1

private const val FTS_TABLE_CREATE =
    "CREATE VIRTUAL TABLE $FTS_VIRTUAL_TABLE USING fts3 ($COL_TYPE, $COL_MAKE, $COL_MODEL, $COL_YEAR, $COL_MILEAGE, " +
            "$COL_PRICE)"

class DatabaseTable (context: Context?) {
private val databaseOpenHelper: DatabaseOpenHelper

init {
    databaseOpenHelper = DatabaseOpenHelper(context)
}

private class DatabaseOpenHelper internal constructor(private val helperContext: Context?) :
        SQLiteOpenHelper(helperContext, DATABASE_NAME, null, DATABASE_VERSION) {
    private lateinit var mDatabase: SQLiteDatabase

    override fun onCreate(db: SQLiteDatabase) {
        mDatabase = db
        mDatabase.execSQL(FTS_TABLE_CREATE)
        loadDatabase()
    }

    override fun onUpgrade(db: SQLiteDatabase, oldVersion: Int, newVersion: Int) {
        Log.w(
            TAG,
            "Upgrading database from $oldVersion to $newVersion , which will destroy all old data"
        )

        db.execSQL("DROP TABLE IF EXISTS $FTS_VIRTUAL_TABLE")
        onCreate(db)
    }

    private fun loadDatabase() {
        Thread(Runnable {
            try {
                loadCars()
            } catch (e: IOException) {
                throw RuntimeException(e)
            }
        }).start()
    }

    @Throws(IOException::class)
    private fun loadCars() {
        val inputStream = helperContext?.resources?.openRawResource(R.raw.cars)

        BufferedReader(InputStreamReader(inputStream)).use {reader ->
            var line: String? = reader.readLine()
            while (line != null) {
                val strings: List<String> = line.split(" ").map {it.trim()}
                if (strings.size < 2) continue
                val id = addCar(strings[0], strings[1], strings[2], strings[3], strings[4], strings[5])
                if (id < 0) {
                    Log.e(TAG, "unable to add car: ${strings[1]} ${strings[2]}")
                }
                line = reader.readLine()
            }

        }
    }

    fun addCar(type: String, make: String, model: String, year: String, mileage: String, price: String) : Long {
        val initialValues = ContentValues().apply {
            put(COL_TYPE, type)
            put(COL_MAKE, make)
            put(COL_MODEL, model)
            put(COL_YEAR, year)
            put(COL_MILEAGE, mileage)
            put(COL_PRICE, price)
        }

        return mDatabase.insert(FTS_VIRTUAL_TABLE, null, initialValues)
    }

    fun getAllCars(): Cursor? {
        val db = this.readableDatabase
        return db.rawQuery("SELECT * FROM $FTS_VIRTUAL_TABLE", null)
    }
}

}

这时我的问题是，使用我目前采用的方法，从getAllCars（）函数访问光标，但是我是Kotlin / Android开发的新手，可能只是完全以错误的方式进行操作。 ..