Thread: Mortgage Calculator Issue

HI all,

I have my code working only problem is that on the first loan its supposed to stop after 84 months, but it goes all the way to 100.
This of course causes a negative ammount to be displayed. I need to figure out how to make only this first load (the 7 year one) stop at 84 months, but the others need to continue past that because they are 180 months and 360 months respectively.

Here is my code:

// Dwight Welsh
/Mortgage Calculator
 
 //Principal = The initial amount of the loan
 //InterestYearly = The annual interest rate (from 1 to 100 percent)
 //InterestMonthly = monthly interest in decimal form = interestYealy / (12 * 100)
 //LengthInYears = the length (in years) of the loan
 //NumberOfPayments = number of months over which loan is amortized = L * 12
 //InterestMonthly = InterestYearly / (12.0*100.0)
 //NumberOfPayments = LengthInYears *12
 //MonthlyPayment = (Principal * InterestMonthly) / (1.0 - (Math.pow(1.0 + InterestMonthly, - NumberOfPayments)))
 
 //This Imports the various classes
 
import java.text.NumberFormat;
import java.util.Date;
import java.util.Scanner;
import java.util.Formatter;
 
 
class Loan {
	public final double principal;
	public final double interestYearly;
	public final int lengthInYears;
 
	public Loan(double principal, double interestYearly, int lengthInYears) {
		this.principal = principal;
		this.interestYearly = interestYearly;
		this.lengthInYears = lengthInYears;
	}
 
	public double ComputeMonthlyInterest() {
		return interestYearly / 12.0;
	}
 
	public double ComputeMonthlyPayment() {
		double interestMonthly = ComputeMonthlyInterest();
		double numberOfPayments = lengthInYears * 12.0;
		return (principal * interestMonthly)
				/ (1.0 - (Math.pow((1.0 + interestMonthly), -numberOfPayments)));
	}
}
 
// File name is Mortgage.java
public class Mortgage {
	private Loan loan;
	private NumberFormat nf;
 
 
   // Calculate and Return the Monthly Payment
 
	public Mortgage(double principal, double interestYearly, int lengthInYears) {
		this(new Loan(principal, interestYearly, lengthInYears));
	}
 
	public Mortgage(Loan loan) {
		this.loan = loan;
		nf = NumberFormat.getCurrencyInstance();
	}
 
   // Displays the Monthly Payment
 
	public void DisplayMonthlyPayment() {
	        double monthlyPayment = loan.ComputeMonthlyPayment();
	        double total = loan.principal;
	        double mrate = loan.ComputeMonthlyInterest();
 
	        //tells the number of lines to show on a screen before asking the user to press enter
	        int linesPerScreen = 20;
 
	        //counts the number of lines (months) printed to the console
	        int monthsCount = 0;
 
	        //This will read input from the console
	        Scanner input = new Scanner(System.in);
 
 
 
			        System.out.println ("Loan amount " + nf.format(loan.principal)
			            + " over " + loan.lengthInYears + " years term at "
			            + (loan.interestYearly * 100) + "% interest rate");
 
			System.out.println("Month\t\tPayment Amount\t\tInterest\tPrincipal");
 
             //Start of Loop code
 
 
	        while (monthsCount < loan.lengthInYears * 12){
				for( int k = 0 ; k < linesPerScreen ; k++ ){
	                double interest = total * mrate;
	                total -= (monthlyPayment - interest);
 				           System.out.printf ("%2d\t\t%s\t\t%s\t\t%s\n",
					                		monthsCount+1, nf.format(monthlyPayment), nf.format(interest), nf.format(total));;
 
 
	            	//This will cause the month to increase
	            	monthsCount = monthsCount+1;
				}
 
				System.out.println ("Press Enter to continue...");
				input.nextLine();
	    }
	}
 
	public static void main(String[] args) {
 
		System.out.println("Dwight Welsh: " + new Date());
		Mortgage pgm = new Mortgage(200000, 0.0535, 7);
		pgm.DisplayMonthlyPayment();
		Mortgage pgm2 = new Mortgage(200000, 0.0550, 15);
		pgm2.DisplayMonthlyPayment();
		Mortgage pgm3 = new Mortgage(200000, 0.0575, 30);
		pgm3.DisplayMonthlyPayment();
 
	}
 
}

Thanks in advance

COY