Working calulator

Author: hellowahab

.idea/vcs.xml

@@ -1,3 +1,6 @@
+/*
+ * https://studyviewer.com/android-calculator-in-kotlin-using-android-studio/
+ */
 package com.personalized.calculator
 
 import androidx.appcompat.app.AppCompatActivity
@@ -10,7 +13,7 @@ import net.objecthunter.exp4j.ExpressionBuilder
 
 class MainActivity : AppCompatActivity() {
 
- lateinit var outputTextView: TextView
+ //lateinit var outputTextView: TextView
  var lastNumaric: Boolean= false
  var stateError: Boolean = false
  var lastDot :Boolean=false
@@ -21,12 +24,13 @@ class MainActivity : AppCompatActivity() {
 
  fun onDigit(view: View)
  {
+ val textView: TextView = findViewById(R.id.textView2) as TextView
  if(stateError)
  {
- outputTextView.text=(view as Button).text
+ textView.text=(view as Button).text
  stateError=false
  }else {
- outputTextView.append((view as Button).text)
+ textView.append((view as Button).text)
  }
  lastNumaric=true
  }
@@ -35,7 +39,8 @@ class MainActivity : AppCompatActivity() {
  {
  if(lastNumaric && !stateError && !lastDot)
  {
- outputTextView.append(".")
+ val textView: TextView = findViewById(R.id.textView2) as TextView
+ textView.append(".")
  lastNumaric=false
  lastDot=true
  }
@@ -45,7 +50,8 @@ class MainActivity : AppCompatActivity() {
  {
  if(lastNumaric && !stateError)
  {
- outputTextView.append((view as Button).text)
+ val textView: TextView = findViewById(R.id.textView2) as TextView
+ textView.append((view as Button).text)
  lastNumaric=false
  lastDot=false
  }
@@ -54,26 +60,27 @@ class MainActivity : AppCompatActivity() {
 
  fun onClear(view: View)
  {
- this.outputTextView.text= ""
+ val textView: TextView = findViewById(R.id.textView2) as TextView
+ textView.text = ""
  lastNumaric=false
  stateError=false
  lastDot=false
  }
  fun onEqual(view: View)
  {
-
+ val textView: TextView = findViewById(R.id.textView2) as TextView
  if(lastNumaric && !stateError)
  {
- val text = outputTextView.text.toString()
+ val text = textView.text.toString()
  val expression= ExpressionBuilder(text).build()
  try
  {
  val result= expression.evaluate()
- outputTextView.text= result.toString()
+ textView.text= result.toString()
  lastDot=true
  }catch (ex:Exception)
  {
- outputTextView.text="Error"
+ textView.text="Error"
  stateError=true
  lastNumaric=false
  }