private void EnterButton_Click(object sender, EventArgs e) { if (itemTextBox.Text == "") { MessageBox.Show("Please enter number of item!"); return; } if (weightTextBox.Text == "") { MessageBox.Show("Please enter weight!"); return; } double currentWeight = refrigerator.GetCurrentWight(Convert.ToInt32(itemTextBox.Text), Convert.ToDouble(weightTextBox.Text)); if (currentWeight == 0) { MessageBox.Show("Your given amount can’t be entered because it will be over flown."); return; } double remainingWeight = refrigerator.GetRemainingWeight(); currentWeightTextBox.Text = currentWeight.ToString(); remainingWeightTextBox.Text = remainingWeight.ToString(); }