Make a CALCULATOR App with Xamarin Android #2 (Code)

Learn how to code the logic of this simple calculator in C#. It’s easier than you think and it is certainly a lot of fun!the GitHub repository: https://github.com/ResoCoder/Simple-Calculator—Xamarin-Android

MainActivity.cs

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using Android.App; using Android.Widget; using Android.OS; using Android.Views; using System;   namespace CalculatorAndroidTut {     [Activity(Label = "CalculatorAndroidTut", MainLauncher = true)]     public class MainActivity : Activity     {         private TextView calculatorText;           private string[] numbers = new string[2];         private string @operator;           protected override void OnCreate(Bundle savedInstanceState)         {             base.OnCreate(savedInstanceState);               // Set our view from the "main" layout resource             SetContentView(Resource.Layout.Main);               calculatorText = FindViewById<TextView>(Resource.Id.calculator_text_view);         }           [Java.Interop.Export("ButtonClick")]         public void ButtonClick (View v)         {             Button button = (Button)v;             if ("0123456789.".Contains(button.Text))                 AddDigitOrDecimalPoint(button.Text);             else if ("÷×+-".Contains(button.Text))                 AddOperator(button.Text);             else if ("=" == button.Text)                 Calculate();             else                 Erase();         }           private void AddDigitOrDecimalPoint(string value)         {             int index = @operator == null ? 0 : 1;               if (value == "." && numbers[index].Contains("."))                 return;               numbers[index] += value;               UpdateCalculatorText();         }           private void AddOperator(string value)         {             if (numbers[1] != null)             {                 Calculate(value);                 return;             }               @operator = value;               UpdateCalculatorText();         }           private void Calculate(string newOperator = null)         {             double? result = null;             double? first = numbers[0] == null ? null : (double?)double.Parse(numbers[0]);             double? second = numbers[1] == null ? null : (double?)double.Parse(numbers[1]);               switch (@operator)             {                 case "÷":                     result = first / second;                     break;                 case "×":                     result = first * second;                     break;                 case "+":                     result = first + second;                     break;                 case "-":                     result = first - second;                     break;             }               if (result != null)             {                 numbers[0] = result.ToString();                 @operator = newOperator;                 numbers[1] = null;                 UpdateCalculatorText();             }         }           private void Erase()         {             numbers[0] = numbers[1] = null;             @operator = null;             UpdateCalculatorText();         }           private void UpdateCalculatorText() => calculatorText.Text = $"{numbers[0]} {@operator} {numbers[1]}";     } }