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

Question

I created a simple room database in kotlin with the help of some online tutorials it gives correct output in the log but doesn't show the desired result in listview
the code

    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()
}

I am not sure what about { it.itemName } and its other friends do, it works in the log as of below snippet

                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}")

this is my adapter 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
    }
}

the screenshot of the output

I know something is wrong with the >hashmap but I can't figure out what's wrong (i have assigned string names correctly)

Answer 1

the following changes were to be made in the main activity

 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)