public string getAmortizationTable()
{
StringBuilder table = new StringBuilder();
bool valid;
valid = calculateAmortizationTable();
if (valid == true)
{
try
{
for (int count = 0; count <= amortizationTable.GetUpperBound(0); count++)
{
table.Append(amortizationTable[count].Period.ToString() + "\t");
table.Append(amortizationTable[count].LoanBalance_Formatted + "\t");
table.Append(amortizationTable[count].PrincipalBalance_Formatted + "\t");
table.Append(amortizationTable[count].InterestBalance_Formatted + "\t");
table.Append(amortizationTable[count].PrincipalPaid_Formatted + "\t");
table.Append(amortizationTable[count].InterestPaid_Formatted + "\n");
}
}
catch (Exception ex)
{
InputUtilities.showErrorMessage(ex, "Unable to create Amortization Table");
table.Length = 0;
}
}
return(table.ToString());
}
private void setInputErrorField(TextBox txtBox)
{
string prompt = "Please re-enter the " + txtBox.Tag + " information";
InputUtilities.showErrorMessage(prompt, "Invalid " + txtBox.Tag);
txtBox.Focus();
txtBox.SelectAll();
}
private void clearErrorProvider()
{
try
{
errorProvider1.SetError(txtMortgageAmount, "");
errorProvider1.SetError(txtInterestRate, "");
errorProvider1.SetError(txtMortgageTerm, "");
errorProvider1.SetError(rtfAmortTable, "");
}
catch (System.Exception ex)
{
InputUtilities.clearException(ex);
}
}
private void findMortgagePayment()
{
string prompt;
bool validPV = false;
bool validAPR = false;
bool validTerm = false;
double principal = 0.0;
double apr = 0.0;
int term = 0;
try
{
//***********************************************************************
//implement input validation and set local variables here
//***********************************************************************
if (validPV && validAPR && validTerm)
{
//***********************************************************************
//declare and create a new mortgage data object
//invoke this class's displayPayment method
//invoke this class's displayAmoritizationTable method
//***********************************************************************
}
else
{
lblAmount.Text = "";
toolTip1.SetToolTip(lblAmount, "");
toolTip1.SetToolTip(rtfAmortTable, "");
if (!validPV)
{
setInputErrorField(txtMortgageAmount);
}
else if (!validAPR)
{
setInputErrorField(txtInterestRate);
}
else
{
setInputErrorField(txtMortgageTerm);
}
}
}
catch (Exception ex)
{
prompt = "Please re-enter the mortgage information and try again";
InputUtilities.showErrorMessage(ex, prompt);
clearFields();
}
}
private void calculateMortgagePayment()
{
double ir;
int np;
try
{
ir = APR / 12 / 100;
np = Term * 12;
mPayment = (mPrincipal * ir) / (1 - Math.Pow(1 + ir, -np));
}
catch (System.InvalidOperationException ex)
{
InputUtilities.showErrorMessage(ex, "Unable to calculate mortgage payment");
}
}
private bool validateInputField(TextBox txtBox, double min, double max)
{
double val;
string errorMessage;
bool valid;
errorMessage = "Enter a number greater than or equal to " + min
+ " and less than or equal to " + max
+ " in the " + txtBox.Tag;
try
{
errorProvider1.SetError(txtBox, "");
if (txtBox.Text == "")
{
errorProvider1.SetError(txtBox, errorMessage);
valid = false;
}
else
{
val = Double.Parse(txtBox.Text);
if (val < min || val > max)
{
errorProvider1.SetError(txtBox, errorMessage);
valid = false;
}
else
{
errorProvider1.SetError(txtBox, "");
valid = true;
}
}
}
catch (Exception ex)
{
InputUtilities.showErrorMessage(ex, errorMessage);
valid = false;
txtBox.SelectAll();
}
return(valid);
}
private void clearFields()
{
try
{
txtMortgageAmount.Clear();
txtInterestRate.Clear();
txtMortgageTerm.Clear();
rtfAmortTable.Clear();
clearErrorProvider();
clearPayment();
}
catch (System.Exception ex)
{
InputUtilities.showErrorMessage(ex, "Delete loan field information and try again");
}
finally
{
txtMortgageAmount.Focus();
}
}
private void txtInput_KeyDown(object sender, System.Windows.Forms.KeyEventArgs e)
{
TextBox txtBox;
//if a navigation key do not react
try
{
txtBox = (TextBox)(sender);
if (InputUtilities.isNavigationKey(e))
{
errorProvider1.SetError(txtBox, "");
//allow navigation keys to be entered
nonNumberEntered = false;
e.Handled = false;
}
else if (InputUtilities.isNumericKey(e))
{
errorProvider1.SetError(txtBox, "");
nonNumberEntered = false;
e.Handled = false;
}
else
{
string errorMessage = "Please enter only numeric values for the " + txtBox.Tag;
errorProvider1.SetError(txtBox, errorMessage);
//stop value form being entered since it is non-numeric
nonNumberEntered = true;
e.Handled = true;
}
}
catch (Exception ex)
{
//do nothing, catch the error later before calculations are done
InputUtilities.clearException(ex);
}
}
private void setMortgageInformation(int selectedMortgage)
{
try
{
clearFields();
if ((selectedMortgage >= PredefinedMortgages.FirstMortgageNumber) && (selectedMortgage <= PredefinedMortgages.LastMortgageNumber))
{
txtMortgageAmount.Text = PredefinedMortgages.DefaultMortgageData[selectedMortgage].Principal.ToString();
txtInterestRate.Text = PredefinedMortgages.DefaultMortgageData[selectedMortgage].APR.ToString();
txtMortgageTerm.Text = PredefinedMortgages.DefaultMortgageData[selectedMortgage].Term.ToString();
}
else
{
txtMortgageAmount.Text = PredefinedMortgages.DEFAULT_PV.ToString();
txtInterestRate.Text = PredefinedMortgages.DEFAULT_PV.ToString();
txtMortgageTerm.Text = PredefinedMortgages.DEFAULT_TERM.ToString();
}
clearErrorProvider();
}
catch (System.Exception ex)
{
InputUtilities.showErrorMessage(ex, "Unable to set mortgage default mortgage information.");
}
}
private bool calculateAmortizationTable()
{
double principal = mortgageInformation.Principal;
double intRate = mortgageInformation.APR / 12 / 100;
int numPayments = mortgageInformation.Term * 12;
double payment = mortgageInformation.Payment;
double loanBalance = 0.0;
double interestPaid = 0.0;
double principalBalance = 0.0;
double interestBalance = 0.0;
double principalPaid = 0.0;
double totalPaid = 0.0;
double totalInterestPaid = 0.0;
bool valid = false;
try
{
//calculate total paid on the loan over the entire term of the loan
totalPaid = numPayments * payment;
//calculate total interest paid over the entire term of the loan
totalInterestPaid = totalPaid - principal;
//make room for the initial entries
amortizationTable = new AmortizationData[numPayments + 1];
//initialize the starting point of the array with the total values
amortizationTable[0] = new AmortizationData(0, totalPaid, principal, totalInterestPaid, 0, 0);
//initialized the Amortization Table to the initial loan values, so start counting at 1
for (int count = 1; count <= amortizationTable.GetUpperBound(0); count++)
{
//calculate loan balance from previous loan balance and mortgage payment
loanBalance = amortizationTable[count - 1].LoanBalance - payment;
//interest payment is the product of the interest rate per period and the remaining balance
//remaining balance is the previous periods Principal Balance
interestPaid = intRate * amortizationTable[count - 1].PrincipalBalance;
//calculate new principal balance from previous principle balance, payment, and interest paid
principalBalance = amortizationTable[count - 1].PrincipalBalance - (payment - interestPaid);
//calculate interest balance using previous interest balance and new interest payment
interestBalance = amortizationTable[count - 1].InterestBalance - interestPaid;
//Calculate principal paid using previous principle paid, payment, and interest paid
principalPaid = amortizationTable[count - 1].PrincipalPaid + (payment - interestPaid);
//Calculate total interest paid, using the previous total interest paid and current interest paid
totalInterestPaid = amortizationTable[count - 1].InterestPaid + interestPaid;
//'generate new data entry in the amortization table
//period, loanBalance, principleBalance, interestBalance, principalPaid, interestPaid
amortizationTable[count] = new AmortizationData(count,
loanBalance,
principalBalance,
interestBalance,
principalPaid,
totalInterestPaid);
}
valid = true;
}
catch (Exception ex)
{
InputUtilities.showErrorMessage(ex, "Unable to create Amortization Table");
valid = false;
}
return(valid);
}