RecyclerView in Kotlin

Introduction#

I just want to share my little bit knowledge and code of RecyclerView using Kotlin.

Main class and Adapter

I am assuming that you have aware about the some syntax of Kotlin and how to use, just add RecyclerView in activity_main.xml file and set with adapter class.

class MainActivity : AppCompatActivity(){
    
        lateinit var mRecyclerView : RecyclerView
        val mAdapter : RecyclerAdapter = RecyclerAdapter()
    
        override fun onCreate(savedInstanceState: Bundle?) {
            super.onCreate(savedInstanceState)
            setContentView(R.layout.activity_main)
            val toolbar = findViewById(R.id.toolbar) as Toolbar
            setSupportActionBar(toolbar)
    
            mRecyclerView = findViewById(R.id.recycler_view) as RecyclerView
    
            mRecyclerView.setHasFixedSize(true)
            mRecyclerView.layoutManager = LinearLayoutManager(this)
            mAdapter.RecyclerAdapter(getList(), this)
            mRecyclerView.adapter = mAdapter
        }
    
        private fun getList(): ArrayList<String> {
            var list : ArrayList<String> = ArrayList()
            for  (i in 1..10) { // equivalent of 1 <= i && i <= 10
                println(i)
                list.add("$i")
            }
            return list
        }
    }

this one is your recycler view adapter class and create main_item.xml file what you want

class RecyclerAdapter : RecyclerView.Adapter<RecyclerAdapter.ViewHolder>() {

    var mItems: ArrayList<String>  = ArrayList()
    lateinit var mClick : OnClick

    fun RecyclerAdapter(item : ArrayList<String>, mClick : OnClick){
        this.mItems = item
        this.mClick = mClick;
    }

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        val item = mItems[position]
        holder.bind(item, mClick, position)
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
        val layoutInflater = LayoutInflater.from(parent.context)
        return ViewHolder(layoutInflater.inflate(R.layout.main_item, parent, false))
    }

    override fun getItemCount(): Int {
        return mItems.size
    }

    class ViewHolder(view: View) : RecyclerView.ViewHolder(view) {
        val card = view.findViewById(R.id.card) as TextView
        fun bind(str: String, mClick: OnClick, position: Int){
            card.text = str
            card.setOnClickListener { view ->
                mClick.onClickListner(position)
            }
        }
    }
}