Why isn't the TextView showing up on the app interface?

Question

So far I've had a bit of help with this, but am still trying to get the Cost Of Service (an editable text) into another TextView to be displayed for my Tip Calculator. Here's the code:

MainActivity.kt

package com.example.tiptime

import android.app.Activity
import android.content.Context
import android.os.Bundle
import android.view.MotionEvent
import android.view.View
import android.view.inputmethod.InputMethodManager
import android.widget.EditText
import androidx.appcompat.app.AppCompatActivity
import androidx.fragment.app.Fragment
import com.example.tiptime.databinding.ActivityMainBinding
import java.text.NumberFormat

class MainActivity : AppCompatActivity() {

    private lateinit var binding: ActivityMainBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)

        binding.calculateButton.setOnClickListener { calculateTip() }

    }

    fun calculateTip() {
        val stringInTextField = binding.costOfServiceEditText.text.toString()
        val cost = stringInTextField.toDoubleOrNull()
        if (cost == null) {
            binding.tipResult.text = ""
            return
        }

        val tipPercentage = when (binding.tipOptions.checkedRadioButtonId) {
            R.id.option_twenty_percent -> 0.20
            R.id.option_eighteen_percent -> 0.18
            else -> 0.15
        }

        var tip = tipPercentage * cost
        if (binding.roundUpSwitch.isChecked) {
            tip = kotlin.math.ceil(tip)
        }

        val formattedTip = NumberFormat.getCurrencyInstance().format(tip)
        binding.tipResult.text = getString(R.string.tip_amount, formattedTip)





        val editText = findViewById<EditText>(R.id.cost_of_service_edit_text)
        val textValue = editText.text.toString()

        val textView = findViewById<EditText>( R.id.cost_of_service_edit_text )
        textView.setText(textValue)


    }

}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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"
    android:padding="16dp"
    tools:context=".MainActivity">

    <ImageView
        android:id="@+id/icon_cost_of_service"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:importantForAccessibility="no"
        app:srcCompat="@drawable/ic_store"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="@id/cost_of_service"
        app:layout_constraintBottom_toBottomOf="@id/cost_of_service"/>

    <com.google.android.material.textfield.TextInputLayout
        android:id="@+id/cost_of_service"
        android:layout_width="160dp"
        android:layout_height="wrap_content"
        android:hint="@string/cost_of_service"
        android:layout_marginStart="16dp"
        app:layout_constraintStart_toEndOf="@id/icon_cost_of_service"
        app:layout_constraintTop_toTopOf="parent" >

        <com.google.android.material.textfield.TextInputEditText
            android:id="@+id/cost_of_service_edit_text"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:inputType="numberDecimal"/>
    </com.google.android.material.textfield.TextInputLayout>

    <ImageView
        android:id="@+id/icon_service_question"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:importantForAccessibility="no"
        app:srcCompat="@drawable/ic_service"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="@id/service_question"
        app:layout_constraintBottom_toBottomOf="@id/service_question"/>

    <TextView
        android:id="@+id/service_question"
        style="@style/Widget.TipTime.TextView"
        android:layout_marginTop="16dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/how_was_the_service"
        app:layout_constraintStart_toStartOf="@id/cost_of_service"
        app:layout_constraintTop_toBottomOf="@id/cost_of_service" />

    <RadioGroup
        android:id="@+id/tip_options"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:checkedButton="@id/option_twenty_percent"
        android:orientation="vertical"
        app:layout_constraintStart_toStartOf="@id/service_question"
        app:layout_constraintTop_toBottomOf="@id/service_question">

        <RadioButton
            android:id="@+id/option_twenty_percent"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/amazing_service" />

        <RadioButton
            android:id="@+id/option_eighteen_percent"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/good_service" />

        <RadioButton
            android:id="@+id/option_fifteen_percent"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/ok_service" />
    </RadioGroup>

    <ImageView
        android:id="@+id/icon_round_up"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:importantForAccessibility="no"
        app:srcCompat="@drawable/ic_round_up"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="@id/round_up_switch"
        app:layout_constraintBottom_toBottomOf="@id/round_up_switch"/>


    <com.google.android.material.switchmaterial.SwitchMaterial
        android:id="@+id/round_up_switch"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:checked="true"
        android:text="@string/round_up_tip"
        app:layout_constraintEnd_toEndOf="parent"
        android:layout_marginStart="16dp"
        app:layout_constraintStart_toEndOf="@id/icon_round_up"
        app:layout_constraintTop_toBottomOf="@id/tip_options" />

    <Button
        android:id="@+id/calculate_button"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:text="@string/calculate"
        android:layout_marginTop="8dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="@id/round_up_switch"
        app:layout_constraintTop_toBottomOf="@id/round_up_switch" />

    <TextView
        android:id="@+id/tip_result"
        style="@style/Widget.TipTime.TextView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="8dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toBottomOf="@id/total"
        tools:text="Tip Amount: $10" />

    <TextView
        android:id="@+id/total"
        style="@style/Widget.TipTime.TextView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="8dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toBottomOf="@id/calculate_button"
        tools:text="Total: $10" />

</androidx.constraintlayout.widget.ConstraintLayout>

strings.xml

<resources>
    <style name="Widget.TipTime.TextView" parent="Widget.MaterialComponents.TextView">
        <item name="android:minHeight">@dimen/min_text_height</item>
        <item name="android:gravity">center_vertical</item>
        <item name="android:textAppearance">?attr/textAppearanceBody1</item>
        <item name="android:textSize">25sp</item>
    </style>
    
    <style name="Widget.TipTime.CompoundButton.Switch" parent="Widget.MaterialComponents.CompoundButton.Switch">
        <item name="android:minHeight">@dimen/min_text_height</item>
        <item name="android:gravity">center_vertical</item>
        <item name="android:textAppearance">?attr/textAppearanceBody1</item>
    </style>

    <style name="Widget.TipTime.CompoundButton.RadioButton" parent="Widget.MaterialComponents.CompoundButton.RadioButton">
        <item name="android:paddingStart">8dp</item>
        <item name="android:textAppearance">?attr/textAppearanceBody1</item>
    </style>

    <string name="app_name">Tip Time</string>
    <string name="cost_of_service">Cost of Service</string>
    <string name="how_was_the_service">How was the service?</string>
    <string name="amazing_service">Amazing (20%)</string>
    <string name="good_service">Good (18%)</string>
    <string name="ok_service">Okay (15%)</string>
    <string name="round_up_tip">Round up tip?</string>
    <string name="calculate">Calculate</string>
    <string name="tip_amount">Tip Amount: %s</string>
    <string name="total">Total: %s</string>
</resources>

What it looks like now:

What it should look like:

Answer 1

you are not placing total value there with binding. Add this line

binding.total.text = getString(R.string.total, totalCost)

so that calculateTip() looks like

...
binding.tipResult.text = getString(R.string.tip_amount, formattedTip)
binding.total.text = getString(R.string.total, totalCost) 
...

and apply logic to calculate totalCost from editText value + tip.

edit: formatting