CODEWITHSUNDEEP
androidkotlinandroid-recyclerview
Iona Bartishvili
Iona Bartishvili

Reputation: 97

Implement custom interface in RecyclerViewAdapter with Kotlin in Android

I have RecyclerView Implemented in my app. i want to change, add and remove items remotely with notifyItemRemoved and notifyItemChanged and not with setDataChange due to performance difference. i want to make some interface objects i guess but i coudn't figured it out how or where to implement and override inteface method, ect.

this is my implementation of RecyclerView in MainActivity.kt 

val linearLayoutManager = LinearLayoutManager(this)
    recyclerView.layoutManager = linearLayoutManager

    adapter = RecyclerAdapter(itemList)
    recyclerView.adapter = adapter

this is my Interface:

public interface AddItemListener {
    void addItem(int position);
}

and this is my RecyclerView class with its ViewHolder:

class RecyclerAdapter(val items: ArrayList<RecyclerViewListModel>) :
RecyclerView.Adapter<RecyclerAdapter.MyViewHolder>() {


    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =
        MyViewHolder(LayoutInflater.from(parent.context).inflate(R.layout.item_recycler_view, parent, false))

    override fun getItemCount(): Int = items.size

    override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
        holder.onBind()
    }


    inner class MyViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
        fun onBind(){}
    }

}

i have Floating button in MainActivity. i want to have access Viewholder in order to add element. thanks in advance !

Upvotes: 1

Views: 2822

Answers (1)

Kasım &#214;zdemir
Kasım &#214;zdemir

Reputation: 5644

Add a listener to your adapter like this:

class RecyclerAdapter(val items: ArrayList<RecyclerViewListModel>, internal var listener: AddItemListener) :
RecyclerView.Adapter<RecyclerAdapter.MyViewHolder>() {


override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) =
    MyViewHolder(LayoutInflater.from(parent.context).inflate(R.layout.item_recycler_view, parent, false))

override fun getItemCount(): Int = items.size

override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
    holder.onBind()
}

fun addNewItem(item : RecyclerViewListModel){
   items.add(item)
   notifyItemInserted(items.size - 1)
}

fun removeItem(position : Int){
   items.removeAt(position)
   notifyItemRemoved(position)
}

inner class MyViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView),
    View.OnClickListener {
    override fun onClick(v: View?) {
        listener. addItem(adapterPosition)
    }

    init {
        itemView.setOnClickListener(this)
    }

    fun onBind(){}
  }
}

add click listener in your activity/fragment:

adapter = RecyclerAdapter(itemList, this)

implement AddItemListener fun:

override fun addItem(int position){
   // you can get item click position
   // you can show the dialog as like "Do you want to delete?"
   adapter.romoveItem(position) 
}

add new item:

val fab: FloatingActionButton = findViewById(R.id.fab)
fab.setOnClickListener { view ->
     adapter.addNewItem(RecyclerViewListModel(verb1, verb2....))
}

Upvotes: 2

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