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I am not sure about #3.
2. Declare a variable at the beginning of the main method for an array list that stores strings.
3. after codes that calculate, format, and display the result for each calculation, add a code that formats a string with the results of the calculation then stores the string to an array list.
Did I even complete #2 correctly. Could someone provide an example so I can get a better understanding?
it is suppose to print in a row. I think I need to use a rectangular array too.
Here is my code
import java.text.*;
import java.util.ArrayList;
public class FutureValueApp
{
public static void main(String[] args)
{
ArrayList<String> code = new ArrayList<String>();//I ADDED THIS
// display a welcome message
System.out.println("Welcome to the Future Value Calculator");
System.out.println();
// perform 1 or more calculations
Scanner sc = new Scanner(System.in);
String choice = "y";
while (choice.equalsIgnoreCase("y"))
{
// get the input from the user
System.out.println("DATA ENTRY");
double monthlyInvestment = getDoubleWithinRange(sc,
"Enter monthly investment: ", 0, 1000);
double interestRate = getDoubleWithinRange(sc,
"Enter yearly interest rate: ", 0, 30);
int years = getIntWithinRange(sc,
"Enter number of years: ", 0, 100);
// calculate the future value
double monthlyInterestRate = interestRate/12/100;
int months = years * 12;
double futureValue = calculateFutureValue(
monthlyInvestment, monthlyInterestRate, months);
// get the currency and percent formatters
NumberFormat currency = NumberFormat.getCurrencyInstance();
NumberFormat percent = NumberFormat.getPercentInstance();
percent.setMinimumFractionDigits(1);
// format the result as a single string
String results =
"Monthly investment:\t"
+ currency.format(monthlyInvestment) + "\n"
+ "Yearly interest rate:\t"
+ percent.format(interestRate/100) + "\n"
+ "Number of years:\t"
+ years + "\n"
+ "Future value:\t\t"
+ currency.format(futureValue) + "\n";
// print the results //I ADDED THIS
System.out.println();
System.out.println("FORMATTED RESULTS");
System.out.println("Inv/Mo.\tRate\t\t\tYears\t\t\tFuture\tValue");
System.out.println("------.\t----\t\t\t-----\t\t\t------\t-----");
System.out.println(code);
// see if the user wants to continue
System.out.print("Continue? (y/n): ");
choice = sc.next();
System.out.println();
}
}
public static double getDouble(Scanner sc, String prompt)
{
boolean isValid = false;
double d = 0;
while (isValid == false)
{
System.out.print(prompt);
if (sc.hasNextDouble())
{
d = sc.nextDouble();
isValid = true;
}
else
{
System.out.println("Error! Invalid decimal value. Try again.");
}
sc.nextLine(); // discard any other data entered on the line
}
return d;
}
public static double getDoubleWithinRange(Scanner sc, String prompt,
double min, double max)
{
double d = 0;
boolean isValid = false;
while (isValid == false)
{
d = getDouble(sc, prompt);
if (d <= min)
System.out.println(
"Error! Number must be greater than " + min + ".");
else if (d >= max)
System.out.println(
"Error! Number must be less than " + max + ".");
else
isValid = true;
}
return d;
}
public static int getInt(Scanner sc, String prompt)
{
boolean isValidInt = false;
int i = 0;
while (isValidInt == false)
{
System.out.print(prompt);
if (sc.hasNextInt())
{
i = sc.nextInt();
isValidInt = true;
}
else
{
System.out.println("Error! Invalid integer value. Try again.");
}
sc.nextLine(); // discard any other data entered on the line
}
return i;
}
public static int getIntWithinRange(Scanner sc, String prompt,
int min, int max)
{
int i = 0;
boolean isValid = false;
while (isValid == false)
{
i = getInt(sc, prompt);
if (i <= min)
System.out.println(
"Error! Number must be greater than " + min + ".");
else if (i >= max)
System.out.println(
"Error! Number must be less than " + max + ".");
else
isValid = true;
}
return i;
}
public static double calculateFutureValue(double monthlyInvestment,
double monthlyInterestRate, int months)
{
double futureValue = 0;
for (int i = 1; i <= months; i++)
{
futureValue =
(futureValue + monthlyInvestment) *
(1 + monthlyInterestRate);
}
return futureValue;
}
}
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