Problems updating recycler views with sqlite database in kotlin - sqlite

Question

I am writing a code that deletes the item from the database when the button of the popup menu is pressed , and deletes it according to the recycler viewer.
selected item is deleted from the database, but not from the recycler view.
error code: No error code
PrintActivity.kt
class PrintActivity : AppCompatActivity() {
val helper = SqliteHelper(this, "myDB.sql", 1)
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
val vBinding = ActivityPrintBinding.inflate(layoutInflater)
setContentView(vBinding.root)
var recyclerViewAdapter = CustomAdapter()
recyclerViewAdapter.listData = helper.select()
vBinding.myRecyclerView.adapter = recyclerViewAdapter
vBinding.myRecyclerView.layoutManager = LinearLayoutManager(this)
vBinding.myRecyclerView.addItemDecoration(
DividerItemDecoration(this, DividerItemDecoration.VERTICAL)
)
}
inner class CustomAdapter : RecyclerView.Adapter<CustomAdapter.Holder>(){
var listData = ArrayList<questionType>()
inner class Holder(val vBinding: QuestionLayoutRecyclerBinding) :
RecyclerView.ViewHolder(vBinding.root){
fun setData(id:Int?, question: String, answer: String, exp: String) {
vBinding.printId.text=id.toString()
vBinding.myLinear.setOnClickListener {
var myPopupMenu = PopupMenu(this#PrintActivity, it)
menuInflater?.inflate(R.menu.menu, myPopupMenu.menu)
var listener = PopupMenuListener()
myPopupMenu.setOnMenuItemClickListener(listener)
myPopupMenu.show()
}
}
inner class PopupMenuListener:PopupMenu.OnMenuItemClickListener{
override fun onMenuItemClick(p0: MenuItem?): Boolean {
listData[adapterPosition].id?.let { helper.delete(it) }
//here
this#CustomAdapter.notifyDataSetChanged()
return false
}
}
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): CustomAdapter.Holder {
val vBinding = QuestionLayoutRecyclerBinding.inflate(
LayoutInflater.from(parent.context),
parent,
false
)
return Holder(vBinding)
}
override fun onBindViewHolder(holder: Holder, position: Int) {
val question = listData[position]
holder.setData(question.id, question.question, question.answer, question.exp)
}
override fun getItemCount(): Int {
return listData.size
}
}
}

Answer 1

You can try this approach using higher order function as callback mechanism.
One recommendation I would give is you can try to avoid these nested inner classes and make into separate files. Hope it works
inner class CustomAdapter : RecyclerView.Adapter<CustomAdapter.Holder>(){
var listData = ArrayList<questionType>()
fun deleteItem(position: Int) { //Function to remove recyclerview item
listData.remove(position)
notifyItemRemoved(position)
notifyItemRangeChanged(position, getItemCount())
}
inner class Holder(val vBinding: QuestionLayoutRecyclerBinding) :
RecyclerView.ViewHolder(vBinding.root){
fun setData(id:Int?, question: String, answer: String, exp: String,itemRemovedCallback:(a:Int)->Unit) { //higher order callback function
vBinding.printId.text=id.toString()
vBinding.myLinear.setOnClickListener {
var myPopupMenu = PopupMenu(this#PrintActivity, it)
menuInflater?.inflate(R.menu.menu, myPopupMenu.menu)
var listener = PopupMenuListener(itemRemovedCallback) //Passed to popupmenu listener
myPopupMenu.setOnMenuItemClickListener(listener)
myPopupMenu.show()
}
}
inner class PopupMenuListener(val itemRemovedCallback:(a:Int)->Unit):PopupMenu.OnMenuItemClickListener{
override fun onMenuItemClick(p0: MenuItem?): Boolean {
listData[adapterPosition].id?.let { helper.delete(it) }
itemRemovedCallback.invoke(adapterPosition) //Calling function. It will pass position to function in adapter
return false
}
}
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): CustomAdapter.Holder {
val vBinding = QuestionLayoutRecyclerBinding.inflate(
LayoutInflater.from(parent.context),
parent,
false
)
return Holder(vBinding)
}
override fun onBindViewHolder(holder: Holder, position: Int) {
val question = listData[position]
holder.setData(question.id, question.question, question.answer, question.exp,::deleteItem) //Passing function as higher order function to viewholder
}
override fun getItemCount(): Int {
return listData.size
}
}