HB Blog 157: Listview In Android Using Kotlin.

Kotlin is now an official language on Android. It's expressive, concise, and powerful. Best of all, it's interoperable with our existing Android languages and runtime.

Basically, it is not very hard to write a code in Kotlin language but, we need to start from class day 1.
Lets say, for getting started in kotlin you can refer link, Get Started with Kotlin on Android
There are few syntax to be adopted and file format as .kt instead of .java.

In this tutorial, I will show how to create a listview with custom adapter in Kotlin Android Application,

Refer the below link for complete sample code:-

Download Sample Code

Have a look on few code snippets,

//MainActivity.kt

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97

package com.harshalbenake.koltinlist import android.content.Intent import android.graphics.Color import android.os.Bundle import android.support.v7.app.AppCompatActivity import android.widget.EditText import android.widget.ListView import android.widget.Toast import kotlinx.android.synthetic.main.activity_main.* /** * Main Activity */ class MainActivity : AppCompatActivity() { //array variable initialized var listItems = arrayListOf() //listview initialized private lateinit var lv_nameslist: ListView override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) //smartcast - textview appearance changed without findViewById tv_name.text = "Enter name for adding to list" tv_name.setTextColor(Color.parseColor("#006500")) tv_name.textSize = 20F //editext variable using findViewById val et_name = findViewById(R.id.et_name) lv_nameslist = findViewById(R.id.lv_nameslist) //arraylist item added listItems.add("harshalbenake1") listItems.add("harshalbenake2") listItems.add("harshalbenake3") //variable value initialized and added to list var newName = "harshalbenake4" newName = "harshalbenake5" listItems.add(newName) //adapter set setAdapter(listItems) //button onclick event bt_add.setOnClickListener() { //methods called to add name addName("harshalbenake6") addName(et_name.text.toString()) } //listview onitemclick event lv_nameslist.setOnItemClickListener { parent, view, position, id -> //item value retrived from positon var strName = parent.getItemAtPosition(position) as String //toast display Toast.makeText(this,strName,Toast.LENGTH_SHORT).show() //data passed to another activity val intent=Intent(this,DetailActivity::class.java) intent.putExtra("strNamePass", strName) startActivity(intent); } } override fun onPause() { super.onPause() //lifecycle method override println("onPause called") } /** * add Name */ fun addName(strString: String) { //empty value check if(strString!="") { listItems.add(strString) setAdapter(listItems) }else{ Toast.makeText(this,"No Name Added",Toast.LENGTH_SHORT).show() } } /** * set Adapter */ fun setAdapter(items: ArrayList) { //CustomBaseAdapter class parameterized constructor called var adapter = CustomBaseAdapter(items, this) //adapter set to listview lv_nameslist.adapter = adapter } }

//CustomBaseAdapter.kt

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

package com.harshalbenake.koltinlist import android.content.Context import android.graphics.Color import android.view.LayoutInflater import android.view.View import android.view.ViewGroup import android.widget.BaseAdapter import android.widget.TextView /** * Custom Base Adapter */ class CustomBaseAdapter(list: ArrayList, context: Context) : BaseAdapter() { //LayoutInflater initialized val mInflater: LayoutInflater = LayoutInflater.from(context) //list passed from mainactivity copyied to locallist var localList = list override fun getCount(): Int { return localList.size } override fun getItem(position: Int): Any { return localList[position] } override fun getItemId(position: Int): Long { return position.toLong() } override fun getView(position: Int, convertView: View?, parent: ViewGroup): View? { val view: View? val viewHolder: ViewHolder if (convertView == null) { view = mInflater.inflate(R.layout.rowitem_name, parent, false) viewHolder = ViewHolder(view) view?.tag = viewHolder } else { view = convertView viewHolder = view.tag as ViewHolder } viewHolder.tv_rowitemname.setTextColor(Color.parseColor("#654657")) viewHolder.tv_rowitemname.textSize = 20F viewHolder.tv_rowitemname.text = localList.get(position).toString() return view } /** * View Holder class */ private class ViewHolder(row: View) { var tv_rowitemname: TextView //view initialized using findViewById init { this.tv_rowitemname = row.findViewById(R.id.tv_rowitemname) } } }

//DetailActivity.kt

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

package com.harshalbenake.koltinlist import android.support.v7.app.AppCompatActivity import android.os.Bundle import kotlinx.android.synthetic.main.activity_detail.* /** * Detail Activity class */ class DetailActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_detail) //intent data extracted var strName= intent.getStringExtra("strNamePass") tv_detailname.text=strName } }