Kotlin Edit Text as Integer - android-studio

Question

I want to make an app where you have to guess two numbers that eaquals a random number. But my app crash at the start because of java.lang.NumberFormatException: For input string: ""
val intNumber1 = etNumber1.text.toString().toInt() is the line that causes the crash. But I dont know what to do.
Here is my main activity:
//Buttons und Text initialisieren
private lateinit var btnCheck: Button
private lateinit var tvRndNumber: TextView
private lateinit var etNumber1: EditText
private lateinit var etNumber2: EditText
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
//Buttons und Text verknüpfen
btnCheck = findViewById(R.id.checkButton)
tvRndNumber = findViewById(R.id.randomNumber)
etNumber1 = findViewById(R.id.inputNumber1)
etNumber2 = findViewById(R.id.inputNumber2)
val intNumber1 = etNumber1.text.toString().toInt()
val intNumber2 = etNumber2.text.toString().toInt()
fun getRandomNumber(): Int {
return Random.nextInt(0,100)
}
var intRdnNumber = getRandomNumber()
tvRndNumber.text = intRdnNumber.toString()
fun checkNumbers(num1: Int, num2: Int){
if (num1 + num2 == intRdnNumber) {
tvRndNumber.text = "Richtig"
}
else {
Toast.makeText(this,"Probier es nochmal", Toast.LENGTH_LONG).show()
}
}
btnCheck.setOnClickListener {
checkNumbers(intNumber1, intNumber2)
}

Answer 1

Try like the following
//....
val intNumber1 = etNumber1.text.toString()
val intNumber2 = etNumber2.text.toString()
//.....
btnCheck.setOnClickListener {
if(intNumber1.isNotEmpty && intNumber2.isNotEmpty{
checkNumbers(intNumber1.toInt(), intNumber2.toInt())
}else{
// input filed is empty
// show message or do nothing
}
}

Answer 2

val intNumber1 = if(etNumber1.text.isNotEmpty()) {
etNumber1.text.toString().toInt()
} else {
0
}
val intNumber2 = if(etNumber2.text.isNotEmpty()) {
etNumber2.text.toString().toInt()
} else {
0
}