无法在 kotlin 中使用 hashmap 将房间数据库数据显示到列表视图 (Android)

Question

我借助一些在线教程在 kotlin 中创建了一个简单的房间数据库，它在日志中提供了正确的输出，但在列表视图中没有显示所需的结果
代码

    var dataList = ArrayList<HashMap<String, String>>()
    fun loadIntoList() {

        dataList.clear()
        var db = Room.databaseBuilder(applicationContext, AppDb::class.java, "BookDB").build()

        val thread = Thread {
            db.bookDao().getAllItems().forEach()
            {

                val map = HashMap<String, String>()
                map.put("name", { it.itemName }.toString())
                map.put("quantity", { it.quantity }.toString())
                map.put("gst", { it.gst }.toString())
                map.put("amount", { it.amount }.toString())
                dataList.add(map)
            }
            findViewById<ListView>(R.id.listView).adapter =
                CustomAdapter(this@MainActivity, dataList)
 }
  thread.start()
}

我不确定 { it.itemName } 和它的其他朋友做了什么，它在下面代码段的日志中有效

                Log.i("Fetch Records", "Id:  : ${it.itemId}")
                Log.i("Fetch Records", "Item Name:  : ${it.itemName}")
                Log.i("Fetch Records", "Quantity:  : ${it.quantity}")
                Log.i("Fetch Records", "GST%:  : ${it.gst}")
                Log.i("Fetch Records", "Amount:  : ${it.amount}")

这是我的适配器class

class CustomAdapter(
    private val context: Context,
    private val ItemDataList: ArrayList<HashMap<String, String>>
) : BaseAdapter() {

    private val inflater: LayoutInflater =
        this.context.getSystemService(Context.LAYOUT_INFLATER_SERVICE) as LayoutInflater

    override fun getCount(): Int {
        return ItemDataList.size
    }

    override fun getItem(position: Int): Int {
        return position
    }

    override fun getItemId(position: Int): Long {
        return position.toLong()
    }

    override fun getView(position: Int, convertView: View?, parent: ViewGroup): View {
        var dataitem = ItemDataList[position]

        val rowView = inflater.inflate(R.layout.list_row, parent, false)
        rowView.findViewById<TextView>(R.id.row_name).text = dataitem["name"]
        rowView.findViewById<TextView>(R.id.row_quantity).text = dataitem["quantity"]
        rowView.findViewById<TextView>(R.id.row_gst).text = dataitem["gst"]
        rowView.findViewById<TextView>(R.id.row_amount).text = dataitem["amount"]

        rowView.tag = position
        return rowView
    }
}

输出截图

我知道 >hashmap 出了点问题，但我不知道出了什么问题（我已经正确分配了字符串名称）

Answer 1

将在主要 activity

中进行以下更改

 val map = HashMap<String, String>()
                map.put("name", it.itemName)
                map.put("quantity", it.quantity)
                map.put("gst",it.gst)
                map.put("amount",it.amount)
                dataList.add(map)

无法在 kotlin 中使用 hashmap 将房间数据库数据显示到列表视图 (Android)

cannot show room database data to listview using hashmap in kotlin (Android)

android

kotlin

android-listview

hashmap

android-room