LoanCompare.java

/*
Rahim Siddiq
Apr 21 2023
Financial application: Compare loans with various interest rates
*/

import java.util.Scanner;

public class LoanCompare
{
    public static void main(String[] args)
    {
        // Program variables
        int numberOfYears;
        double loanAmount, annualInterestRate, monthlyInterestRate, monthlyPayment, totalPayment;

        // Title of program and description of program function to user
        System.out.println(" ====================================================================");
        System.out.println(" ============== Financial Application: Compare Loans ================");
        System.out.println(" ====================================================================");
        System.out.println("     This program calculates the monthly payments for a loan with    ");
        System.out.println("     different interest rates and displays a table of payments       ");
        System.out.println(" --------------------------------------------------------------------");
        System.out.println();

        // Scanner object for input
        Scanner input = new Scanner(System.in);

        // User input
        System.out.print(" Enter the loan amount: ");
        loanAmount = input.nextDouble();

        System.out.print(" Enter the number of years: ");
        numberOfYears = input.nextInt();

        // Display the header for the table
        System.out.printf("\n %-20s %-20s %-20s \n", "Interest Rate", "Monthly Payment", "Total Payment");
        System.out.println(" --------------------------------------------------------------------");
        
        // Loop through interest rates from 5% to 8%, with an increment of 1/8
        for (annualInterestRate = 5.0; annualInterestRate <= 8.0; annualInterestRate += 0.125)
        {
            // Calculate monthly interest rate and monthly payment
            monthlyInterestRate = annualInterestRate / 1200; // divide by 12 multiply by 100 = 1200
            // Calculate present value using annuity formula
            monthlyPayment = loanAmount * monthlyInterestRate / (1 - 1 / Math.pow(1 + monthlyInterestRate, numberOfYears * 12));
            totalPayment = monthlyPayment * numberOfYears * 12;

            // Display the monthly payment and total payment for the current interest rate .3f for rate .2f for dollar amounts
            System.out.printf(" %-5.3f%%               %-20.2f %-20.2f \n", annualInterestRate, monthlyPayment, totalPayment);
            // Close the Scanner to prevent resource leak
            input.close();
        }
    }
}