Adapter group by name resulting unnecessry group header

Question

I'm trying to make a list that are grouped by it's first name for example

1. Hello
2. Hotel
3. Kargo
4. Kali

and it will result

• H
• Hello
• Hotel
• K
• Kargo
• Kali

I have successfully created the adapter with the result I want but for some reason, unnecessary header is also shown

Incorrectheader

as you can see from the picture above, I don't have a list with letters I or J but for some reason, it still shows up as a group header

how to fix it?

here is the code I use

• Models.kt

  data class SiteModel (
  
    val IDSite: Int,
    val IDPerusahaan:Int? = null,
    val KodeSite:String? = null,
    val NamaSite:String? = null,
    val Alamat:String? = null,
    val Telepon:String? = null,
    val Telepon2:String? = null,
    val JumlahShift:Int? = null,
    val TanggalMulaiBergabung:Timestamp? = null,
    val TanggalSelesaiBergabung:Timestamp? = null,
    val Catatan:String? = null,
    val StatusSite:Int? = null,
    val IDSiteSelesai: Int? = null,
    val QRCodeImage:String? = null,
    val CreateBy:String? = null,
    val CreateAt:Timestamp? = null,
    val LastUpdateBy:String? = null,
    val LastUpdateAt:Timestamp? = null
  
  )
  

• SiteAdapter.kt

  class SiteAdapter(
    private val myActivity: Activity,
    private val myList: List<Models.SiteModel>
  ) : RecyclerView.Adapter<RecyclerView.ViewHolder>() {
  
    private val VIEW_TYPE_GROUP = 0
    private val VIEW_TYPE_ITEM = 1
  
    inner class GroupViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
        val groupTextView: TextView = itemView.findViewById(android.R.id.text1)
    }
  
    inner class ItemViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
        val siteTextView: TextView = itemView.findViewById(android.R.id.text1)
    }
  
  
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
        return if (viewType == VIEW_TYPE_GROUP) {
            val view = LayoutInflater.from(parent.context).inflate(android.R.layout.simple_list_item_1, parent, false)
            GroupViewHolder(view)
        } else {
            val view = LayoutInflater.from(parent.context).inflate(android.R.layout.simple_list_item_1, parent, false)
            ItemViewHolder(view)
        }
    }
  
    override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
        val item = myList[position]
        if (getItemViewType(position) == VIEW_TYPE_GROUP) {
            val groupHolder = holder as GroupViewHolder
            // Set huruf pertama di sini
            groupHolder.groupTextView.text = item.NamaSite!!.substring(0, 1).uppercase()
  
            groupHolder.groupTextView.setBackgroundResource(R.color.primary)
            groupHolder.groupTextView.setTextColor(ContextCompat.getColor(myActivity, R.color.onPrimary))
        } else {
            val itemHolder = holder as ItemViewHolder
            // Set nama site di sini
            itemHolder.siteTextView.text = item.NamaSite!! + " - " + item.KodeSite!!
        }
    }
  
    override fun getItemViewType(position: Int): Int {
        // Cek apakah posisi saat ini merupakan awal dari grup
        val namaSite = myList[position].NamaSite!!.uppercase()
        return if (position == 0 || namaSite[0] != myList[position - 1].NamaSite!!.uppercase()[0]) {
            VIEW_TYPE_GROUP
        } else {
            VIEW_TYPE_ITEM
        }
    }
  
    override fun getItemCount(): Int {
        return myList.size
    }
  }