String out of Range, Help please

I am unsure what to do as I am quite new to Java. I want to repeat this program again but it keeps giving me the error of my string being out of range. How do I approach this?

import java.util.Scanner;
import java.io.*;

public class LoanReport {

    public static void main(String[] args) throws IOException {
        double loanBalance;
        double interestRate;
        int loanYears;
        String answer;
        char again;
        // boolean again;

        Scanner keyboard = new Scanner(System.in);

// while(again)
// do{
        System.out.print(&qu开发者_如何学Pythonot;Enter the " + "loan amount.");
        loanBalance = keyboard.nextDouble();
        System.out.print("Enter the " + "annual interest rate.");
        interestRate = keyboard.nextDouble();
        System.out.print("Enter the " + "years of the loan.");
        loanYears = keyboard.nextInt();

        Amortization am = new Amortization(loanBalance, interestRate, loanYears);

        am.saveReport("LoanAmortization.txt");
        System.out.println("Report saved to " + "the file LoanAmortization.txt.");

        System.out.print("Would you like " + "to run another report? Enter Y for " + "yes or N for no: ");
//answer = keyboard.next(); 
        // again = answer.charAt(0);
//} 
//while(answer == 'Y' || answer  == 'y');
        answer = keyboard.nextLine();
        again = answer.charAt(0);
        if (again == 'N' || again == 'n') {
            System.exit(0);
        }
    }
}

I tried doing a boolean method but I'm unsure if I did that correctly.

String out of range error occurs when you are trying to access a position in a string, in this case answer.charAt(0), that does not exist.

nextLine(): Advances this scanner past the current line and returns the input that was skipped. next(): Finds and returns the next complete token from this scanner. See more here

Try using:

answer = keyboard.next()

instead of:

answer = keyboard.nextLine();

Also, use answer.equals("N") instead of if (answer == "N"), the later one is comparing the reference of the value.