/// <summary>
 /// Construct a default B52WeaponLoader object
 /// </summary>
 public B52WeaponLoader()
 {
     InitializeComponent();
     b52 = new B52();
     WeightLabel.Content = b52.CalcWeight();
     FuelLabel.Content   = b52.Fuel;
 }
 /// <summary>
 /// Add fuel into the loader
 /// </summary>
 private void AddFuel(object sender, RoutedEventArgs e)
 {
     // Allow only positive number in the field
     if (System.Text.RegularExpressions.Regex.IsMatch(FuelTextBox.Text, "[^0-9]"))
     {
         MessageBox.Show("Enter only positive number \n");
         FuelTextBox.Text = "100000";
     }
     else
     {
         int fuelWeight = int.Parse(FuelTextBox.Text);
         try
         {
             b52.AddFuel(fuelWeight);
         }
         catch (FuelErrorException ex)
         {
             MessageBox.Show(ex.Message);
         }
         catch (WeightErrorException ex)
         {
             MessageBox.Show(ex.Message);
         }
         WeightLabel.Content = b52.CalcWeight();
         FuelLabel.Content   = b52.Fuel;
         IsReady();
     }
 }