Question

I am getting an error trying to code a program which calculates interest on a loan, and displays information back with certain decimal positions. I need the loanInterest to display at 3.546%, or something like that with 3 decimal places. I was able to get the totalInterest to display properly, but I dont know if this is because it was a new value I just established. When I try to run my program as seen below, I get a “float cannot be dereferenced” error.

public class SarahShelmidineModule2Project {

public static void main(String[] args) {
    //Being programing for Module 2 project

    // Welcome the user to the program
    System.out.println("Welcome to the Interest Calculator");
    System.out.println();  // print a blank line

    // create a Scanner object named sc
    Scanner sc = new Scanner(System.in);

    // perform interest calculations until choice isn't equal to "y" or "Y"
    String choice = "y";
    while (choice.equalsIgnoreCase("y"))
    {
        // get info from user on loan amount and interest rates and store data
        System.out.print("Enter loan amount:   ");
        double loanAmount = sc.nextDouble();
        System.out.print("Enter interest rate:   ");
        float loanInterest = sc.nextFloat();


        // calculate the interest and convert to BigDecimal and rounding for totalInterest

       BigDecimal decimalloanAmount = new BigDecimal (Double.toString(loanAmount));
       BigDecimal decimalloanInterest = new BigDecimal (Double.toString(loanInterest));
       BigDecimal totalInterest = decimalloanAmount.multiply(decimalloanInterest);
       totalInterest = totalInterest.setScale(2, RoundingMode.HALF_UP);

       loanInterest = loanInterest.setScale(3, RoundingMode.HALF_UP);

        System.out.println();  // print a blank line

        // display the loan amount, loan interest rate, and interest
        // also format results to percent and currency
        NumberFormat currency = NumberFormat.getCurrencyInstance();
        NumberFormat percent = NumberFormat.getPercentInstance();

        String message =    "Loan amount: " + currency.format(loanAmount) + "\n"
                +           "Interest rate:  " + percent.format(loanInterest) + "\n"
                +           "Intrest:    " + currency.format(totalInterest) + "\n";
        System.out.println(message);

        // inquire if user would like to continue with application
        System.out.print("Continue? (y/n): ");
        choice = sc.next();
        System.out.println();

Below is the error I get when I run this:

Welcome to the Interest Calculator

Enter loan amount: 10932

Enter interest rate: .0934

Exception in thread "main" java.lang.RuntimeException: Uncompilable
source code - Erroneous sym type: <any>     at
 sarahshelmidinemodule2project.SarahShelmidineModule2Project.main(SarahShelmidineModule2Project.java:45)

Answer 1

Just change

float loanInterest = sc.nextFloat();

with

BigDecimal loanInterest = new BigDecimal(sc.nextFloat());

and you will resolve “float cannot be derefenced” since float is a primitive type and has not method setScale.

About printing right number of decimals, use something like this:

    String currencySymbol = Currency.getInstance(Locale.getDefault()).getSymbol();
    System.out.printf("%s%8.5f\n", currencySymbol, totalInterest);

This code will use 5 decimals, but be sure that your BigDecimal scale is at least 5, otherwise you will get not significant zeros.