how to get integers from edittext and multiply them using kotlin

Question

I cannot seem to figure out how to take the value entered into a textedit, convert to srting/int and then multiply them together. I have 3 inputs i want multiplied with a button click and then displayed in the text of a text view. as a exercise to see if my button works and changing the text view was working, i used append and it works, I just cant get them to multiply.

looking over some of these threads I still cannot seem to make it work:

Android - How to get text from edittext and calculate them?

Android - How to get text from edittext and calculate them?

Convert EditText input to integer and multiply?

Fragment Code in Koltin (with what i need missing)

import android.os.Bundle
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import kotlinx.android.synthetic.main.MultiplyExample.*

class MultiplyExample : Fragment() {

override fun onCreateView( inflater: LayoutInflater, container: 
ViewGroup?, savedInstanceState: Bundle? ): View? {

return inflater.inflate(R.layout.fragment_retention, container, false) }
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {

super.onViewCreated(view, savedInstanceState)

button.setOnClickListener(object : View.OnClickListener {
override fun onClick(v: View) {

val a: Int = length.text.toString().toInt()
val b: Int = flight.text.toString().toInt()
val c: Int = rotation.text.toString().toInt()

Working as append with stringbuilder#

val sb = StringBuilder()
sb.append(a).append(b).append(c)
d.text = sb

XML is the same for a,b,c

<EditText
        android:inputType="number"

Answer 1

Your issue is that you are trying to reference the widgets in the fragments without findViewById.

In your method onCreateView put some code like so before the return statement.

val view = inflater.inflate(R.layout.fragment_retention, container, false)

val a: Int = view.findViewById<TextView>(R.id.length).text.toString().toInt()
val b: Int = view.findViewById<TextView>(R.id.flight).text.toString().toInt()
val c: Int = view.findViewById<TextView>(R.id.rotation).text.toString().toInt()

val multiplication = a * b * c

return view