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How do I do calculations in a separate method then send them back to main for printing?

I am trying to do the calculations for the interest in another method, and I know that I have to make another method outside of main and then put return an the end, but I have no idea what to title this new method and how to go about doing the calculations there. I think it is the while loop that is confusing me. I have done this once before on a different project, so I have an idea of how to do it, but this project isn't anything like the other one and I don't really understand it. Any help is extremely appreciated as I have been working on this for a long time and just want to get it over with. Thanks in advance.
import java.util.Scanner; // This allows for the use of the scanner in the class
public class SavingsAccount // Start of class
{
public static void main(String[]args) // Start of main
{
double P; // These store the amounts that will be used in the accruing interest formula
double i;
double n;
double S = 0;
int timesLooped = 0;
Scanner readConsole = new Scanner(System.in); // This is the scanner
System.out.println("I am a savings account interest calculator."); // Prompts the user for input
System.out.println("How much money have you deposited?");
P = readConsole.nextDouble();
S = P;
System.out.println("Now, what is the annual interest rate? (i.e. .05)");
i = readConsole.nextDouble();
System.out.println("Finally, how long do you plan on having the money in the account?");
n = readConsole.nextDouble();
while (timesLooped <= n)
{
S = S + (P * i);
timesLooped += 1;
}
System.out.println("Your balance in that time span is " + S + "."); // Tells you your ending balance
}
}

Based on your comment, I think you want this:
private static double addInterest(double S, double P, double i)
{
return S + (P * i);
}
...
public static void main()
{
...
while (timesLooped <= n)
{
S = addInterest(S, P, i);
}
EDIT
I made some small improvements just for fun:
I put the entire interest calculation into the function and used exponentiation rather than a loop.
I gave the variables more descriptive names.
I used System.out.format to print the result.
Here's the code:
private static double computeCompoundInterest(double principal, double rate,
double years) {
return principal * Math.pow(1 + rate, years);
}
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.println("I am a savings account interest calculator.");
System.out.println("How much money have you deposited?");
double principal = scanner.nextDouble();
System.out.println("Now, what is the annual interest rate? (i.e. .05)");
double rate = scanner.nextDouble();
System.out.println("How many years will you hold that money in the account?");
double years = scanner.nextDouble();
double total = computeCompoundInterest(principal, rate, years);
System.out.format("Your balance at the end of that period will be %.2f.\n", years, total);
}

UserInput Method keeps assigning a different value in java

this is my first question on the site. I am a fresh CS student needing some help with something that is probably really simple. The code as is will compile. When I enter in the values as the program asks, it stores the values wrong. It will store the right values for gross pay and savings rate but the IRA rate comes back as 100% even when entered at 6.9 and it seems it stores the IRA rate in saveAmount. Please halp me figure out what I am doing wrong here.
import java.text.DecimalFormat;
import java.util.*;
public class CollinDunn_1_05 {
static Scanner console = new Scanner(System.in);
static DecimalFormat formatCash = new DecimalFormat("#,###.00");
static double iraTotal = 0.0;
static double saveAmount = 0.0;
static double totalSave = 0.0;
static String line = "";
public static void main (String [] args) {
// Input variables
double grossPay = 0.0; // The gross pay from a users paycheck
double saveRate = 0.0; // This is the user entered savings rate
double iraRate= 0.0; // The IRA investment rate
String whichOne = ""; // A temp variable to pass a string type into UserInput
printInfo();
grossPay = userInput("gross pay");
saveRate = userInput("savings rate");
iraRate = userInput("IRA rate");
iraTotal = iraAmount(grossPay, iraRate);
saveAmount = savingsAmount(grossPay, saveRate);
outputResults(grossPay, saveRate, saveAmount, iraRate, iraTotal);
return;
} // End Main
public static void printInfo() {
System.out.println ("This program uses methods to calculate \n"
+ "savings amounts and IRA investment amounts \n"
+ "from user input consisiting of their gross pay, \n"
+ "their desired savings rate and IRA rate, made by "
+ " Collin Dunn");
return;
} // End ProgramInfo
public static double userInput(String whichOne) {
double saveMe = 0.0;
System.out.print("Please enter your " + whichOne + ": ");
saveMe = console.nextDouble();
return saveMe;
} // End userInput
public static double iraAmount(double grossPay, double iraRate) {
iraTotal = grossPay * (iraRate / 100.0);
return iraTotal;
} // End iraAmount
public static double savingsAmount(double grossPay, double saveRate) {
saveAmount = grossPay * (saveRate / 100.0);
return saveAmount;
} // End savingsAmount
public static void outputResults(double grossPay, double saveRate, double iraRate,
double saveAmount, double iraTotal) {
totalSave = saveAmount + iraTotal;
System.out.print ("With a gross pay of $" + formatCash.format(grossPay)
+ ", a savings rate of %" + formatCash.format(saveRate)
+ " and a IRA rate of %" +formatCash.format(iraRate)
+ ".\n Your savings amount will be $" + formatCash.format(saveAmount)
+ ", with a investment amount of $" + formatCash.format(iraTotal)
+ ".\n Which leaves you with a total savings of $" +
+ totalSave + ". Way to go for paying yourself!" );
return;
} // End outputResults
} //End Class

Your only issue is the order of arguments you pass to or have set on the outputResults() method.
Change the signature of the method to:
public static void outputResults(double grossPay, double saveRate, double saveAmount, double iraRate, double iraTotal) {
Which now matches how you call the method:
outputResults(grossPay, saveRate, saveAmount, iraRate, iraTotal);
Let me make a couple of additonal suggestions:
1) You are consistently naming arguments in your method signatures the same names as global variables, which makes it confusing which is which when accessing the variable in the method. Either avoid using the same names for the method input variables, or use something like this.amount = amount to make it more obvious of your intention.
2) Avoid static unless you have a valid reason to use it (which is pretty rare).
Instead, take advantage of Java's Object oriented nature and create an instance of your class in the main method and call methods on that instance. This will make your code more readable, reliable, and reusable.
3) In a method that returns type 'void', you don't need to add the empty return; statement.
To correct your issue and also demonstrate the points I listed, I have refactored your code and provided it below. By the way, you have a lot of potential. Despite the fact there are a few details you can improve, for being a first year CS student, your code is well written and thought out. Good job!
import java.text.DecimalFormat;
import java.util.*;
public class CollinDunn_1_05 {
DecimalFormat formatCash = new DecimalFormat("#,###.00");
double iraTotal = 0.0;
double saveAmount = 0.0;
double totalSave = 0.0;
double grossPay = 0.0; // The gross pay from a users paycheck
double saveRate = 0.0; // This is the user entered savings rate
double iraRate= 0.0; // The IRA investment rate
public CollinDunn_1_05(double gross, double saveRt, double iraRt){
this.grossPay = gross;
this.saveRate = saveRt;
this.iraRate = iraRt;
}
public void calculate(){
calcIraAmount();
calcSavingsAmount();
}
public static void main (String [] args) {
Scanner scanner = new Scanner(System.in);
printInfo();
CollinDunn_1_05 program = new CollinDunn_1_05(
userInput("gross pay", scanner),
userInput("savings rate", scanner),
userInput("IRA rate", scanner)
);
program.calculate();
program.outputResults();
} // End Main
public static void printInfo() {
System.out.println ("This program uses methods to calculate \n"
+ "savings amounts and IRA investment amounts \n"
+ "from user input consisiting of their gross pay, \n"
+ "their desired savings rate and IRA rate, made by "
+ " Collin Dunn");
return;
} // End ProgramInfo
public static double userInput(String whichOne, Scanner console) {
double saveMe = 0.0;
System.out.print("Please enter your " + whichOne + ": ");
saveMe = console.nextDouble();
return saveMe;
} // End userInput
public void calcIraAmount() {
iraTotal = grossPay * (iraRate / 100.0);
} // End iraAmount
public void calcSavingsAmount() {
saveAmount = grossPay * (saveRate / 100.0);
} // End savingsAmount
public void outputResults() {
totalSave = saveAmount + iraTotal;
System.out.print ("With a gross pay of \$" + formatCash.format(grossPay)
+ ", a savings rate of %" + formatCash.format(saveRate)
+ " and a IRA rate of %" +formatCash.format(iraRate)
+ ".\n Your savings amount will be \$" + formatCash.format(saveAmount)
+ ", with a investment amount of \$" + formatCash.format(iraTotal)
+ ".\n Which leaves you with a total savings of \$" +
+ totalSave + ". Way to go for paying yourself!" );
} // End outputResults
} //End Class

Proper Formatting

I have the program working I just need help cutting off the extra numbers, Im not very skilled at using the printf statements when printing in Java. When I run it I get output like 1225.043 Here is what I have:
import java.util.Scanner;
public class Comparison {
public static void main(String[] args)
{
Scanner keyboard = new Scanner(System.in);
float amount;
double principal = 1000.00;
double rate;
System.out.println("Enter interest rate");
rate = keyboard.nextDouble();
System.out.println("Year" +" "+ "Amount on deposit");
for(int year = 1; year <= 10; ++year)
{
amount = (float) (principal * Math.pow(1.0 + rate, year));
System.out.println(year+ " "+ amount);
System.out.println();
}
}
}

Try
System.out.printf("%2d %.2f%n", year, amount);
Output:
Enter interest rate
0.1
Year Amount on deposit
1 1100.00
2 1210.00
3 1331.00
4 1464.10
5 1610.51
6 1771.56
7 1948.72
8 2143.59
9 2357.95
10 2593.74

Separate two loops in java

I should write a program that reads balance and interest rate, and displays the value of the account in ten years with anually, monthly and daily compounds.
I have written for yearly compounding and for monthly. In the second loop for monthly rate, program reads value of "balance" after compounding yearly, while I need it read primary value. How is it possible to separate two loops, so they do not influence each other? Here is my code:
import java.util.Scanner;
public class BankInterest {
public static void main(String []args) {
System.out.println("Please enter your balance: ");
Scanner keyboard = new Scanner(System.in);
double balance = keyboard.nextDouble();
int years = 0;
int months = 0;
int days = 0;
System.out.println("Please enter the ann1ual interest rate in decimal form: ");
double interestRate = keyboard.nextDouble();
while (years<10) {
double interest = balance * interestRate;
balance = balance + interest;
years++;
}
System.out.println("Balance after 10 years with annual interest is " + balance);
while (months<120) {
double interest = balance * interestRate/12;
balance = balance + interest;
months++;
}
System.out.println("Balance after 10 years with monthly interest rate is " + balance);
}
}
When program is run and I input 100 for balance and 0.02 to interest rate, yearly compounding works well and displays:
Balance after 10 years with annual interest is 121.89944199947573
And second loop takes this value as balance and displays:
Balance after 10 years with monthly interest rate is 148.86352955791543
While, if my code was right it should display this number: 122.119943386

You can place both loops in different functions and pass both balance and interesRate as arguments, like below.
import java.util.Scanner;
public class BankInterest {
static public double annualInterest(double balance, double interestRate) {
int years = 0;
while (years < 10) {
double interest = balance * interestRate;
balance = balance + interest;
years++;
}
return balance;
}
static public double monthlyInterest(double balance, double interestRate) {
int months = 0;
while (months < 120) {
double interest = balance * interestRate/12;
balance = balance + interest;
months++;
}
return balance;
}
public static void main(String args[]) {
Scanner keyboard = new Scanner(System.in);
System.out.println("Please enter your balance: ");
double balance = keyboard.nextDouble();
System.out.println("Please enter the ann1ual interest rate in decimal form: ");
double interestRate = keyboard.nextDouble();
System.out.println("Balance after 10 years with annual interest is " +
annualInterest(balance, interestRate));
System.out.println("Balance after 10 years with monthly interest rate is " +
monthlyInterest(balance, interestRate));
}
}

You need to declare two different variables for initial balance and updated balance so that you can access the original balance in both loops. I have shown this below.
public static void main(String []args) {
System.out.println("Please enter your balance: ");
Scanner keyboard = new Scanner(System.in);
double startingBalance = keyboard.nextDouble();
double finalBalance=0;
int years = 0;
int months = 0;
int days = 0;
System.out.println("Please enter the ann1ual interest rate in decimal form: ");
double interestRateYearly = keyboard.nextDouble();
double interstRateMonthly = interestRateYearly;
double interstRateDayliy = interestRateYearly;
while (years<10) {
double interest = startingBalance * interestRateYearly ;
finalBalance = startingBalance + interest;
years++;
}
System.out.println("Balance after 10 years with annual interest is " + finalBalance);
while (months<120) {
double interest = startingBalance * interstRateMonthly /12;
finalBalance = startingBalance + interest;
months++;
}
System.out.println("Balance after 10 years with monthly interest rate is " + finalBalance);
}
}

Adding "$" to right aligned numbers and Scanner class not running, java [closed]

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I am having two problems with my code.
First: I can't seem to add "$" in the right location (I cant get it to look like $10.00 only 10.00$)
Second: Adding a Scanner class ends up with the program "running" but nothing happening. (if I set gross with a number it runs fine but not with using a scanner class)
import java.util.Scanner;
public class Payment
{
public static void main(String[] args)
{
Scanner Keyboard = new Scanner(System.in);
//double gross = Keyboard.nextDouble(); will not work
//double gross = 8000; will work
double fed = (0.15 * gross);
double state = (0.035 * gross);
double soc = (0.0575 * gross);
double med = (0.0275 * gross);
double pen = (0.05 * gross);
double hea = 75;
double net = (gross - (fed + state + soc + med + pen + hea));
System.out.println("Paycheck calculation by employee\n");
System.out.printf("Gross Amount:%28.2f%n", gross);
System.out.printf("Federal Tax:%29.2f%n", fed);
System.out.printf("State Tax:%31.2f%n", state);
System.out.printf("Social Security Tax:%21.2f%n", soc);
System.out.printf("Medicare/Medicaid Tax:%19.2f%n", med);
System.out.printf("Pension Plan %28.2f%n", pen);
System.out.printf("Health Insurance %24.2f%n%n", hea);
System.out.printf("Net Pay:%33.2f", net);
}
}

You probably want to print out an input prompt. Regarding currency formatting, you could use the DecimalFormat class.
import java.text.DecimalFormat;
import java.util.Scanner;
public class Payment
{
public static void main(String[] args)
{
Scanner keyboard = new Scanner(System.in);
System.out.print("Enter gross amount: ");
double gross = keyboard.nextDouble();
//double gross = 800; //will work
double fed = (0.15 * gross);
double state = (0.035 * gross);
double soc = (0.0575 * gross);
double med = (0.0275 * gross);
double pen = (0.05 * gross);
double hea = 75;
double net = (gross - (fed + state + soc + med + pen + hea));
DecimalFormat currency = new DecimalFormat("$0.00");
System.out.println("Paycheck calculation by employee\n");
System.out.printf("Gross Amount: %27s%n", currency.format(gross));
System.out.printf("Federal Tax:%29s%n", currency.format(fed));
System.out.printf("State Tax:%31s%n", currency.format(state));
System.out.printf("Social Security Tax:%21s%n", currency.format(soc));
System.out.printf("Medicare/Medicaid Tax:%19s%n", currency.format(med));
System.out.printf("Pension Plan %28s%n", currency.format(pen));
System.out.printf("Health Insurance %24s%n%n", currency.format(hea));
System.out.printf("Net Pay:%33s", currency.format(net));
keyboard.close();
}
}

Answering your first question, you could it like this:
System.out.printf("Gross Amount %28c%.2f%n", '$', gross);
Your second question, i think your problem is the Locale. Depending on your Locale, the input format of a Double, in this case, may be different. You could do:
keyboard.useLocale(Locale.US);
This way, the input of a Double will be the integer part separated by a . from the decimal part. 8000 and 5.5 are valid examples of a Double input.