private void depotButton_Click(object sender, EventArgs e) { try { double amount = double.Parse(amountPriceBox.Text); if (amount > 0) { Account account = (Account)accountCombo.SelectedItem; if (account == null) { throw new AccountManagementException("Customer does not have any accounts \r\n OR \r\n No account has been selected."); } else { Cash cashAmount = new Cash(amount); cashAmount.DepositAsset(account); amountPriceBox.Clear(); } } else { MessageBox.Show("amount must be positive"); } } catch (AccountManagementException accMgmtEx) { MessageBox.Show(accMgmtEx.Message); } catch { MessageBox.Show("All fields are required."); } }