omidMirrajei

private var button: Button = findViewById(R.id.button)

omidMirrajei

//Sample 1
private var button: Button = findViewById(R.id.button)

//Sample 2
private var button: Button? = null
private fun init(){ button = findViewById(R.id.button) }

//Sample 3 (The lateinit keyword stands for late initialization. lateinit modifier is allowed only on mutable properties)
private lateinit var button:Button
private fun init(){ button = findViewById(R.id.button) }

omidMirrajei

class MainActivity : AppCompatActivity() {

    private val foodList = arrayListOf("Pizza", "Chiness", "Hamburger", "McDonalds")

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        button_decide.setOnClickListener {
            val randomFood = Random().nextInt(foodList.count())

omidMirrajei

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val initialTextViewTranY = textView_progress.translationY
        seekBar.setOnSeekBarChangeListener(object : SeekBar.OnSeekBarChangeListener {
            override fun onProgressChanged(seekBar: SeekBar?, progress: Int, fromUser: Boolean) {
                textView_progress.text = progress.toString()

omidMirrajei

<?xml version="1.0" encoding="utf-8"?>

    <ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <androidx.constraintlayout.widget.ConstraintLayout
            android:layout_width="match_parent"