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java loop to repeat program

I am extremely new to java I am in my second week in classes or so--
I need my program to keep going or exit according to the user. It is a payroll calculation and I want the end to say "Do you want to continue (y/n)" I want Y to repeat my entire program of questions and no to end program. I am using Jgrasp and I am very very new. I am assuming it needs a loop and I am not totally sure, I just got this to run and compile correctly-- it runs correctly for me so it is a good start and I am hoping to get help on how to do this as I am seeing a ton of different ways and different programs for it. thanks.
import java.util.Scanner;
public class calculations {
public static void main(String [] args) {
Scanner reader = new Scanner(System.in);
Scanner in = new Scanner(System.in);
double Regpay;
double Payperhour;
int HoursAweek;
double Pay;
double OvertimeHours;
double OvertimePay;
double Dependants;
double SocSecTax;
double FederalTax;
double StateTax;
int UnionDues;
double AllTaxes;
double FinalPay;
String playAgain;
System.out.print("Enter your pay per hour:");
Payperhour = reader.nextDouble ();
System.out.print("Enter your regular Hours a week:");
HoursAweek = reader.nextInt();
System.out.print("Enter your overtime hours:");
OvertimeHours = reader.nextDouble();
Regpay = Payperhour * HoursAweek;
OvertimePay = OvertimeHours * 1.5 * Payperhour;
Pay = OvertimePay + Regpay;
SocSecTax = Pay * .06;
FederalTax = Pay * .14;
StateTax = Pay * .05;
UnionDues = 10;
AllTaxes = SocSecTax + FederalTax + StateTax + UnionDues;
FinalPay = Pay -= AllTaxes;
System.out.println("Your pay this week will be " +FinalPay);
{
System.out.println("How many Dependants:");
Dependants = reader.nextInt();
if (Dependants >= 3) {
Dependants = Pay + 35;
System.out.println("Your Pay is:" +Dependants);
} else if(Dependants < 3) {
System.out.println("Your Pay is:" +Pay);
}
}
}
}

Here is the basic idea with your code:
import java.util.Scanner;
public class calculations{
public static void main(String [] args) {
Scanner reader = new Scanner(System.in);
Scanner in = new Scanner(System.in);
double Regpay;
double Payperhour;
int HoursAweek;
double Pay;
double OvertimeHours;
double OvertimePay;
double Dependants;
double SocSecTax;
double FederalTax;
double StateTax;
int UnionDues;
double AllTaxes;
double FinalPay;
String playAgain;
int runAgain = 1;
while (runAgain == 1) {
System.out.print("Enter your pay per hour:");
Payperhour = reader.nextDouble();
System.out.print("Enter your regular Hours a week:");
HoursAweek = reader.nextInt();
System.out.print("Enter your overtime hours:");
OvertimeHours = reader.nextDouble();
Regpay = Payperhour * HoursAweek;
OvertimePay = OvertimeHours * 1.5 * Payperhour;
Pay = OvertimePay + Regpay;
SocSecTax = Pay * .06;
FederalTax = Pay * .14;
StateTax = Pay * .05;
UnionDues = 10;
AllTaxes = SocSecTax + FederalTax + StateTax + UnionDues;
FinalPay = Pay -= AllTaxes;
System.out.println("Your pay this week will be " + FinalPay);
{
System.out.println("How many Dependants:");
Dependants = reader.nextInt();
if (Dependants >= 3) {
Dependants = Pay + 35;
System.out.println("Your Pay is:" + Dependants);
} else if (Dependants < 3) {
System.out.println("Your Pay is:" + Pay);
}
}
System.out.println("Again??? Press 1 to run again and 0 to exit");
runAgain = reader.nextInt();
}
}
}

Here's a guide for you..
You can create a method for the transaction.
//Place this on your main method
do{
//call the method
transaction();
//ask if the user wants to repeat the program
System.out.print("Do you want to continue (y/n)");
input = reader.nextLine();
}while(input.equalsIgnoreCase("Y"))
public void transaction(){
//your transaction code here..
}

Here is a brief idea of how to do this:
String choice = "y";
while(true) {
//Take input
System.out.print("Do you want to continue (y/n)?");
choice = reader.nextLine();
if(choice.equalsIgnoreCase("n")) break;
//else do your work.
}
You can also sue do-while to get what you want. You may need to make some changes but then that is the entire idea. It is just a hint.

Delete one scanner, Payroll program Week 3 [duplicate]

This question already exists:
Scanner issue when using nextLine after nextXXX [duplicate]
Closed 7 years ago.
How am I able to get rid of one scanner? If I do use just one scanner the after the weekly_pay is output is:
Employee Name
Enter the hours worked for the week.
The program skips right over asking for the employee name variable. With both scanners it does indeed loop asking for the employee name as it should.
//Week 3 Assignment
package weeklypay2;
import java.util.Scanner; // importing the Java utility class scanner
public class WeeklyPay2 // class WeeklyPay
{
//main method
public static void main(String[] args)
{
Scanner Scanner = new Scanner(System.in);
Scanner Scanner1 = new Scanner(System.in);
String employee_name = null; // variable for employee name
double hours_worked = 0, // variable for weekly hours worked
pay_rate = 0, // variable for pay rate per hour
weekly_pay = 0; // weekly pay = hours * pay_rate
while (employee_name!="stop")
{
System.out.println("");
System.out.println("Employee Name"); // prompt, employees name
employee_name = Scanner1.nextLine();
if (employee_name.equalsIgnoreCase("stop"))
{
System.out.print("Exiting Program");
break;
} // ends if statement
else
{
System.out.println("Enter the hours worked for the week");
//prompt, hours worked for the current week
pay_rate = Scanner.nextDouble();
while(pay_rate < 0.01)
{
System.out.print("ERROR!!, Input a postive number: \n");
pay_rate = Scanner.nextDouble();
}
System.out.println("Enter the employees hourly pay rate");
// prompt, the employees pay rate
hours_worked = Scanner.nextDouble();
while(hours_worked < 0.01)
{
System.out.print("ERROR!!, Input a postive number: \n");
hours_worked = Scanner.nextDouble();
}
weekly_pay = (double) hours_worked * (double) pay_rate; // setting the variable weekly_pay
System.out.println(employee_name + "'s weekly pay is $" + weekly_pay ); // output the employees name and weekly pay
}
}
Scanner.close();
Scanner1.close();
} //ends main method
} //ends class WeeklyPay

Well the first thing I would say is be careful naming your scanner. Don't start that with a capital. Now a big thing is you don't want to compare strings using !=, this is not intended for string variables. There is a fun method for comparing strings that would be .equals() or .equalsIgnoreCase() depending if you want it non-case sensitive. Now after changing those few things in your code it works just fine. Also just a heads up Java also includes a method for formatting currency. You're pay numbers were missing a decimal. If you look at the NumberFormat I added after the scanner and then look at the println at the end you can see its very simple to use.
import java.text.NumberFormat;
import java.util.Scanner; // importing the Java utility class scanner
public class WeeklyPay2 // class WeeklyPay
{
//main method
public static void main(String[] args)
{
Scanner scanner = new Scanner(System.in);
NumberFormat format = NumberFormat.getCurrencyInstance();
String employee_name = "";
double hours_worked = 0, // variable for weekly hours worked
pay_rate = 0, // variable for pay rate per hour
weekly_pay = 0; // weekly pay = hours * pay_rate
while (!employee_name.equalsIgnoreCase("stop"))
{
System.out.println();
System.out.print("Employee Name: ");
employee_name = scanner.nextLine();
if (employee_name.equalsIgnoreCase("stop"))
{
System.out.print("Exiting Program");
break;
} // ends if statement
else
{
System.out.print("Enter the hours worked for the week: ");
//prompt, hours worked for the current week
pay_rate = scanner.nextDouble();
while(pay_rate < 0.01)
{
System.out.print("ERROR!!, Input a postive number: ");
pay_rate = scanner.nextDouble();
}
System.out.print("Enter the employees hourly pay rate: ");
// prompt, the employees pay rate
hours_worked = scanner.nextDouble();
while(hours_worked < 0.01)
{
System.out.print("ERROR!!, Input a postive number: \n");
hours_worked = scanner.nextDouble();
}
weekly_pay = (double) hours_worked * (double) pay_rate; // setting the variable weekly_pay
System.out.println(employee_name + "'s weekly pay is: " + format.format(weekly_pay)); // output the employees name and weekly pay
scanner.nextLine();
}
}
scanner.close();
} //ends main method
} //ends class WeeklyPay
And this is the output we would see:
Oh, PS: Keep the program cleaner by prompting for the input on the same line, more intuitive and better to look at. By all means add a line break after the input but not before :)

use Scanner1.nextLine() after getting the value for hours worked.
Refer modified code below:
import java.util.Scanner; // importing the Java utility class scanner
public class WeeklyPay2 // class WeeklyPay
{
//main method
public static void main(String[] args) {
Scanner Scanner1 = new Scanner(System.in);
String employee_name = null; // variable for employee name
double hours_worked = 0, // variable for weekly hours worked
pay_rate = 0, // variable for pay rate per hour
weekly_pay = 0; // weekly pay = hours * pay_rate
//Scanner1.useDelimiter("//n");
while (true) {
System.out.println("");
System.out.println("Employee Name"); // prompt, employees name
employee_name = Scanner1.nextLine();
if (employee_name.equalsIgnoreCase("stop"))
{
System.out.print("Exiting Program");
break;
}// ends if statement
else {
System.out.println("Enter the hours worked for the week");
//prompt, hours worked for the current week
pay_rate = Scanner1.nextDouble();
while (pay_rate < 0.01) {
System.out.print("ERROR!!, Input a postive number: \n");
pay_rate = Scanner1.nextDouble();
}
System.out.println("Enter the employees hourly pay rate");
// prompt, the employees pay rate
hours_worked = Scanner1.nextDouble();
while (hours_worked < 0.01) {
System.out.print("ERROR!!, Input a postive number: \n");
hours_worked = Scanner1.nextDouble();
//Scanner1.
}
Scanner1.nextLine();
weekly_pay = (double) hours_worked * (double)
pay_rate; // setting the variable weekly_pay
System.out.println(employee_name + "'s weekly pay is $" + weekly_pay); // output the employees name and weekly pay
}
}
Scanner1.close();
} //ends main method
}//ends class WeeklyPay

Output user data to display class

package developer;
import java.util.*;
import java.lang.Math.*;
public class Developer
{
static Scanner console = new Scanner(System.in);
String workType; // This will be either an app, or game
String name;
int pay;
int weekPay;
int hrsWorked;
double tax;
public Developer()
{
name = "Ciaran";
}
Developer(String appType, String coderName)
{
workType = appType;
name = coderName;
}// End developer
Developer(String appType, int pay) // Class to choose the pay rate depending on if it is a game or app
{
System.out.println("Are you coding an app or a game? ");
appType = console.next();
if(appType == "app")
{
pay = 20;
}
if(appType == "game")
{
pay = 30;
}
else
{
System.out.println("Please enter either 'app' or 'game' ");
}
}// End developer
Developer(int hrsWorked, double tax, int weekPay, int pay) // Class to choose the tax bracket which the developer is in
{
System.out.println("Please enter how many hours you have worked this week: ");
hrsWorked = console.nextInt();
weekPay = hrsWorked * pay;
if(weekPay >= 865)
{
tax = 0.4;
}
else
{
tax = 0.21;
}
}// End developer
Developer(int weekPay, int tax) // Gets the pay after tax
{
weekPay = weekPay * tax;
}// End developer
public void display()
{
System.out.println("This display method works");
System.out.println("User: " + name);
}
public static void main(String[] args)
{
Developer myDev = new Developer();
myDev.display();
} // End main
}// End public class developer
I am trying to get this program to ask the user what their name is; if they are developing a game or app and the amount of hours worked on it. With all this information I want to calculate how much the dev earns including tax. I cannot seem to get the display() method to ask the user the questions though and I have no idea what to do. I am hoping somebody out there can help me.

System.in will read input from the command line. You should wrap it with a java.util.Scanner and nextLine like this:
Scanner scanner = new Scanner(System.in);
String user_input = scanner.nextLine();
Be sure to check
scanner.hasNextLine()
before continuing or you'll get an error.

There are few things that could be done differently in your code, so let's break it down:
1.No need to make console static type, you can use:
private Scanner console = new Scanner(System.in);
2.weekPay is of type int, but your tax is double, if you don't want weekPay to be cast to integer, change it to:
double weekPay;
3.Later on, you are calculating weekPay after tax, so let's introduce a variable for that:
double weekPayAfterTax;
4.All these Developer() methods are constructors, and I think you are slightly confused here. Of course, you can have many constructors, but for us, let's keep only the no-params constructor:
public Developer() {
name = "Ciaran";
//you could initialise all the other variables here as well,
//I'll leave it as an exercise for you :)
}
5.Let's create a method that will ask all the questions and set respective variables:
void setData() {
//let's get the name
System.out.print("What's your name: ");
name = console.nextLine();
System.out.print("Are you coding an app or a game? ");
//since we want the user to enter 'app' or 'game'
//we need to loop until we got these
//we can do this by creating endless while loop,
//which we will end when we have correct input
while (true) {
workType = console.next();
if (workType.equals("app")) {
pay = 20.0;
//stop the loop
break;
}
else if (workType.equals("game")) {
pay = 30.0;
//stop the loop
break;
}
else {
System.out.print("Please enter either 'app' or 'game': ");
//back to top
}
}
//ok, we're out the loop, let's get number of hours
System.out.print("Please enter how many hours you have worked this week: ");
hrsWorked = console.nextInt();
//calculate weekPay
weekPay = hrsWorked * pay;
if(weekPay >= 865) {
tax = 0.4;
}
else {
tax = 0.21;
}
//calculate pay after tax
weekPayAfterTax = weekPay - weekPay * tax;
}
6.Let's update our display() method to show all the info:
public void display() {
System.out.println("This display method works");
System.out.println("User: " + name);
System.out.println("Work type: " + workType);
System.out.println("Pay: " + pay);
System.out.println("Week pay: " + weekPay);
System.out.println("Week pay after tax: " + weekPayAfterTax);
}
7.In your main method, you can finally create an instance of Developer class and get the data:
public static void main(String[] args) {
Developer myDev = new Developer();
myDev.setData();
myDev.display();
}
The code above can be improved (such as checking if user entered number where it's expected), and your problem can of course be done differently, but here's the start.
Please check out some tutorials to learn the basics, such as this one, or this one. Most of all, experiment and don't let others put you down for not understanding something.

How do I make my program continue only if the user enters certain values?

My code is supposed to simulate something similar to a vending machine. But there is a problem when I enter a price that is not one of my options, e.g. 0.82 the program still runs. How do I get it to only accept one of my options?
import java.util.Scanner;
public class VendingMachine
{
public static void main (String[] args)
{
double price;
Scanner keyboard = new Scanner(System.in);
System.out.println("Choose your price. Your options are: ");
double i;
for (i=0.25; i<=1.25; i+=0.25)
System.out.printf("$%.2f\n", i );
System.out.println("Enter your selection now: ");
price=keyboard.nextDouble();
System.out.printf("You chose the $%.2f option. ",price);
double deposit;
if (price<=1.00) {
System.out.println("Please insert 1 dollar. *This machine only accepts Loonies*");
deposit=1;
} else {
System.out.println("Please insert 2 dollars.*This machine only accepts Loonies*");
deposit=2;
}
System.out.println("Please press 'Enter' to simulate inserting money. ");
new Scanner(System.in).nextLine();
double change;
change = deposit-price;
System.out.printf("Your change is $%.2f\n",change);
}
}
I tried something like this but it doesn't work. What is the best way to do this.
if (price==i)
System.out.println("You entered " + price);
else {
System.out.println("Invalide choice. Please try again.")
System.exit(0);
}
Here is an image if you find it easier to read.

You can use some sort of loop (while, do-while, for), which will continue to excecute the code until a condition is (or isn't) met.
Here is an example:
do {
code line 1;
code line 2;
code line 3;
...
} while(yourCondition);
If yourCondition is satisfied (yourCondition == true), the code will go back to code line 1 (will perform the code block between do and while) and it'll stop once the condition isn't satisfied(yourCondition == false). yourCondition could be any expression that returns a true/false result (boolean), such as 2+2==4.
If you want to keep looping for as long as yourCondition isn't met, you can add a ! before your expression, which will evaluate the opposite of your boolean like this (!yourCondition).
Now, if you understood how that works, you can easily apply it to your code.

If you want the user to enter only your displayed prices, I suggest the following, you shall edit to your exact desires.
//given you an open scanner
boolean isCorrectPrice = false;
System.out.println("enter price");
price = in.nextDouble();
while(!isCorrectPrice)
{
if(price%0.25==0 && price<=1.25 && price>0)
{
System.out.println("you entered "+price);
IsCorrectPrice = true;
continue;
}
System.out.println("incorrect price, re-enter ");
price = in.nextDouble();
}
//your code after user enters correct price
That will do the check. If your prices change, all you have to do is change the maximum price provided its still dividable with 0.25 or the condition price check.

Use BigDecimal (instead of double) to work with money. Its exact -- double isn't.
http://docs.oracle.com/javase/6/docs/api/java/math/BigDecimal.html
I would write a function to get the user input. It would not return until the
user had entered an allowed value.

Although my real answer is the one on the comments, you can use something like this. To check recursively if the correct value was given.
import java.util.Scanner;
public class VendingMachine {
static Scanner keyboard = new Scanner(System.in);
public static void main(String[] args) {
System.out.println("Choose your price. Your options are: ");
for (double i = 0.25; i <= 1.25; i += 0.25) {
System.out.printf("$%.2f\n", i);
}
double price = checkMultipleValues(0.25,1.25, 0.25);
System.out.printf("You chose the $%.2f option. ", price);
double deposit;
if (price <= 1.00) {
System.out.println("Please insert 1 dollar. *This machine only accepts Loonies*");
deposit = 1;
} else {
System.out.println("Please insert 2 dollars.*This machine only accepts Loonies*");
deposit = 2;
}
System.out.println("Please press 'Enter' to simulate inserting money. ");
new Scanner(System.in).nextLine();
double change;
change = deposit - price;
System.out.printf("Your change is $%.2f\n", change);
}
private static double checkMultipleValues(double initial,double last,double step) {
System.out.println("Enter your selection now: ");
double price = keyboard.nextDouble();
for (double i = initial; i <= last; i += step) {
if (price == i) {
return price;
}
}
return checkMultipleValues( initial, last, step);
}
}
ADDENDUM
Since you like #Sello answer why don't you combine it with #MrD and have something like
do {
System.out.println("enter price");
price = in.nextDouble();
// System.out.println("you entered " + price);
} while (!(price % 0.25 == 0 && price <= 1.25 && price > 0));

Java loan calculator

I'm trying to code a loan calculator. I seem to be having issues. I am trying to get an input from the user and validate the input. I know I am doing it wrong the problem is I'm scratching my head wondering how to do it right.
I get a red line on the d = getDouble(sc, prompt); and the i = getInt(sc, prompt); which I understand I don't have that coded correctly. I'm just unsure how to go about fixing it.
I also have to validate the continue statement which I wasn't to sure the best way to go about that and finally the instructor expects the code to be 80 lines or less which I am right about 80 lines. I guess I'm looking for a better way to do this but being new I'm scratching my head and I'm hoping someone can lend a hand.
As always I really appreciate the help.
import java.util.Scanner;
import java.text.NumberFormat;
public class LoanCalculator
{
public static double getDoubleWithinRange(Scanner sc, String prompt, double min, double max)
{
double d = 0.0;
boolean isValid = false;
while(isValid == false);
{
d = getDouble(sc, prompt);
if (d <= min)
{
System.out.println("Error! Number must be greater tha 0.0");
}
else if (d >= max)
{
System.out.println("Error number must be less than 1000000.0");
}
else
isValid = true;
}
return d;
}
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 more than 0");
else if (i >= max)
System.out.println("Error! Number must be less than 100");
else
isvalid = true;
}
}
public static void main(String[] args)
{
System.out.println("Welcome to the loan calculator");
Scanner sc = new Scanner(System.in);
String choice = "y";
while (choice.equalsIgnoreCase("y"))
{
System.out.println("DATA ENTRY");
double loanAmount = getDoubleWithinRange(sc, "Enter loan amount: ", 0.0, 1000000.0);
double interestRate = getDoubleWithinRange(sc, "Enter yearly interest rate: ", 0, 20);
int years = getIntWithinRange(sc, "Enter number of years: ", 0, 100);
int months = years * 12;
double monthlyPayment = loanAmount * interestRate/
(1 - 1/Math.pow(1 + interestRate, months));
NumberFormat currency = NumberFormat.getCurrencyInstance();
NumberFormat percent = NumberFormat.getPercentInstance();
percent.setMaximumFractionDigits(3);
System.out.println("RESULST");
System.out.println("Loan Amount" + currency.format(loanAmount));
System.out.println("Yearly interest rate: " + percent.format(interestRate));
System.out.println("Number of years: " + years);
System.out.println("Monthly payment: " + currency.format(monthlyPayment));
System.out.println();
System.out.println("Continue? (y/n): ");
choice =sc.next();
System.out.println();
}
}
}

You haven't made the implementation of your getDouble(Scanner,String) and getInt(Scanner,String) that's why you're getting the red line.
since you already have a scanner, and prompt string change it to this
System.out.print(prompt);
d = sc.nextDouble();
and for the integer
System.out.print(prompt);
i = sc.nextInt();

I think getDouble and getInt are string functions so you would have to get a string first then call those methods. However, since you have a scanner, I assume you want to use that with the nextXXX methods:
Scanner sc = new Scanner (System.in);
double d = sc.nextDouble();
You can use this complete snippet for educational purposes:
import java.util.Scanner;
class Test {
public static void main (String args[]) {
Scanner sc = new Scanner (System.in);
System.out.print("Enter your double: ");
double d = sc.nextDouble();
System.out.print("Enter your integer: ");
int i = sc.nextInt();
System.out.println("You entered: " + d + " and " + i);
}
}
Transcript:
Enter your double: 3.14159
Enter your integer: 42
You entered: 3.14159 and 42
Basically, the process is:
Instantiate a scanner, using the standard input stream.
Use print for your prompts.
Use the scanner nextXXX methods for getting the input values.
A little more assistance here, based on your comments.
In your main function, you have:
double loanAmount = getDoubleWithinRange(sc, "Enter loan amount: ", 0.0, 1000000.0)
and that function has the prototype:
public static double getDoubleWithinRange(
Scanner sc, String prompt, double min, double max)
That means those variables in the prototype will be set to the values from the call. So, to prompt for the information, you could use something like (and this is to replace the d = getDouble(sc, prompt); line):
System.out.print(prompt);
double d = sc.nextDouble();
And there you have it, you've prompted the user and input the double from them. The first line prints out the prompt, the second uses the scanner to get the input from the user.
As an aside, your checks for the minimum and maximum are good but your error messages have hard-coded values of 0 and 100K. I would suggest that you use the parameters to tailor these messages, such as changing:
System.out.println("Error! Number must be greater tha 0.0");
into:
System.out.println("Error! Number must be greater than " + min);
That way, if min or max change in future , your users won't get confused :-)
I'll leave it up to you to do a similar thing for the integer input. It is your homework, after all :-)