Thread: Whats wrong with my code?

Hello, I'm trying to make a program that compares loans with interest rates from 5% - 8%, with an increment of 1/8.
The output should look something like:

Loan Amount: 10000
Number of Years: 5
Interest Rate Monthly Payment Total Payment
5% 188.71 11322.74
5.125% 189.28 11357.13
5.25% 189.85 11391.59
...
7.85% 202.16 12129.97
8.0% 202.76 12165.83

I believe that I have gotten the correct Interest Rate, I just can't get the correct numbers for Monthly and Total Payments (I've copied the formula exactly as it shows it in the book within another program). I also can't figure out how to make them adjust with the interest rate.

I'm new to loops so any kind of help will be appreciated,

Thanks

import java.util.Scanner;
 
public class Exercise04_21 {
 
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
 
        System.out.print("Loan Amount: ");
        int loan = input.nextInt();
 
        System.out.print("Number of Years: ");
        int years = input.nextInt();
 
        System.out.printf("%10s      %10s      %10s\n", "Interest Rate", "Monthly Payment", "Total Payment");
 
        double interest = 5.0;
 
        double monthlyPay = loan * (interest / 100) / (1 - 1 / Math.pow(1 + (interest / 100), years * 12));
 
        double total = monthlyPay * 12 * years;
 
        while (interest <= 8.0) {
 
 
            System.out.printf("%10.2f      %10.2f      %10.2f%n", interest, monthlyPay, total);
 
 
            interest += 0.125;
        }
    }
}

The formula is:

(loanAmount * monthlyInterestRate) / 1 - (1 / (1 + monthlyInterestRate)^numberOfYears*12)

, copied from the book. I entered it in using several different variables and 1 long variable and it still won't work...

My new code:

import java.util.Scanner;
 
public class Exercise04_21 {
 
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
 
        System.out.print("Loan Amount: ");
        int loan = input.nextInt();
 
        System.out.print("Number of Years: ");
        int years = input.nextInt();
 
 
 
 
 
        double monthlyPayment;
        double totalPayment;
 
        System.out.println("Interest Rate\tMonthly Payment\tTotal Payment");
        double interest = 5.0;
        while (interest <= 8.0) {
 
            monthlyPayment = (int) (loan * interest
                    / (1 - (Math.pow(1 / (1 + interest), years * 12))) * 100) / 100;
            totalPayment = (int) (((monthlyPayment * 12) * years) * 100) / 100;
 
            System.out.println(interest + "\t\t" + monthlyPayment
                    + "\t\t" + totalPayment);
 
            interest +=0.125;
        }
    }
}

The output when I enter 10000 for the loan and 5 for the year (same as the example in the first post) is:

Loan Amount: 10000
Number of Years: 5
Interest Rate Monthly Payment Total Payment
5.0 50000.0 3000000.0
5.125 51250.0 3075000.0
5.25 52500.0 3150000.0
5.375 53750.0 3225000.0
5.5 55000.0 3300000.0
5.625 56250.0 3375000.0
5.75 57500.0 3450000.0
5.875 58750.0 3525000.0
6.0 60000.0 3600000.0
6.125 61250.0 3675000.0
6.25 62500.0 3750000.0
6.375 63750.0 3825000.0
6.5 65000.0 3900000.0
6.625 66250.0 3975000.0
6.75 67500.0 4050000.0
6.875 68750.0 4125000.0
7.0 70000.0 4200000.0
7.125 71250.0 4275000.0
7.25 72500.0 4350000.0
7.375 73750.0 4425000.0
7.5 75000.0 4500000.0
7.625 76250.0 4575000.0
7.75 77500.0 4650000.0
7.875 78750.0 4725000.0
8.0 80000.0 4800000.0

Loan Amount: 10000
Number of Years: 5
Interest Rate Monthly Payment Total Payment
5.0/// / 50000.0--- 3000000.0
5.125// 51250.0--- 3075000.0
5.25/// 52500.0--- 3150000.0
5.375// 53750.0--- 3225000.0
5.5/// 55000.0--- 3300000.0
5.625// 56250.0--- 3375000.0
5.75/// 57500.0--- 3450000.0
5.875// 58750.0--- 3525000.0
6.0//// 60000.0--- 3600000.0
6.125// 61250.0--- 3675000.0
6.25/// 62500.0--- 3750000.0
6.375// 63750.0--- 3825000.0
6.5//// 65000.0--- 3900000.0
6.625// 66250.0--- 3975000.0
6.75/// 67500.0--- 4050000.0
6.875// 68750.0--- 4125000.0
7.0//// 70000.0--- 4200000.0
7.125// 71250.0--- 4275000.0
7.25/// 72500.0--- 4350000.0
7.375// 73750.0--- 4425000.0
7.5/// 75000.0--- 4500000.0
7.625// 76250.0--- 4575000.0
7.75/// 77500.0--- 4650000.0
7.875// 78750.0--- 4725000.0
8.0//// 80000.0--- 4800000.0

Re-posted this to hopefully make it more readable.

I copied that code from an even number example done by my professor, posted on his site. It has to be right..

Could the interest variable that is involved in the loop be affecting it?