How to check the dot button clicked or not

Android
1

I am newbie to Kotlin Android,

I am trying to create an calculator app, In my i need to disable the dot(.) button if the button clicked.

Expecting result
.dot should be entered only once.

Here is my code

package com.tripbegins.calculator

import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import android.widget.Button
import com.tripbegins.calculator.R.id.*
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {

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

var emptyText = true
fun numberEvents(view: View) {
var checkButton:Boolean = false
    if(emptyText){
        viewResult.setText("")
    }
    emptyText = false
    var button = view as Button
    var isClicked = viewResult.text.toString()
    when (button.id) {
        buttonOne.id -> isClicked += "1"
        buttonTwo.id -> isClicked += "2"
        buttonThree.id -> isClicked += "3"
        dotButton.id-> isClicked+="."
    }
       viewResult.setText(isClicked)
}

var operation ="+"
var oldValues:String? = null
fun mathOperation(view: View){
    var mathButton = view as Button
    var isClicked = viewResult.text.toString()

    when(mathButton.id){
        plusButton.id-> {
            operation = "+"
        }
        minusButton.id->{
            operation="-"
        }
        mulButton.id->{
            operation="*"
        }

    }
    oldValues = viewResult.text.toString()
    emptyText = true
}

fun Calculate(view: View){

    var newValues = viewResult.text.toString()
    var calulateButton:Double? = null
    when(operation){
        "+"-> { calulateButton = oldValues!!.toDouble() + newValues.toDouble() }
        "-"-> { calulateButton = oldValues!!.toDouble() - newValues.toDouble() }
        "*"-> { calulateButton = oldValues!!.toDouble() * newValues.toDouble() }

    }
    viewResult.setText(calulateButton.toString())
    emptyText=true
}
fun clearFunction(view: View){
    viewResult.setText("")
}
}

Kindly suggest me an code to restrict the .dot button to be pressed multiple times

2

This is an Android, not Kotlin problem, but buttons have an enabled property that you can set to false.