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Adding more classes to a prewritten program

I am being tasked with adding 2 more classes to a prewritten program, one that does all calculations and one that prints the total bill. I understand how to add other classes but im a bit confused since the program already looks like it does the calculations inside of the main class.
Ive tried just adding in the classes but it throws errors because its missing information obviously.
public static void main(String[] args)
{
String squantity, snumber, output, line_output = "";
String [] item = new String [5];
double [] cost = new double [5];
double [] quantity = new double [5];
double [] amount = new double [5];
int number, i;
double grandtotal = 0;
String costout, amountout, grandtotalout;
DecimalFormat df2 = new DecimalFormat("$##,###.00");
for(i=0;i<=4;++i)
{
output = " Acme Grocery Store" + "\n" +
"1-Green Beans $0.35 per pound" + "\n" +
"2-Yellow Beans $0.40 per pound" + "\n" +
"3-Head Lettuce $0.79 per pound" + "\n" +
"4-Leaf Lettuce $1.98 per pound" + "\n" +
"5-Hot House Tomatoes $0.99 per pound" + "\n" +
"6-Hydro Tomatoes $3.98 per pound" + "\n" + "\n" +
"Please make your selection ";
snumber = JOptionPane.showInputDialog(null,
output, "Input Data", JOptionPane.QUESTION_MESSAGE);
number = Integer.parseInt(snumber);
squantity = JOptionPane.showInputDialog(null,
"Enter Quantity", "Input Data", JOptionPane.QUESTION_MESSAGE);
quantity[i] = Double.parseDouble(squantity);
//code for the calculation
if(number == 1)
{
cost[i] = 0.35;
item[i]="Green Beans";
}
else if(number == 2)
{
cost[i] = 0.4;
item[i]="Yellow Beans";
}
else if(number == 3)
{
cost[i] = 0.79;
item[i]="Head Lettuce";
}
else if(number ==4)
{
cost[i] = 1.98;
item[i]="Leaf Lettuce";
}
else if (number==5)
{
cost[i] = 0.99;
item[i]="Hot House Tomatoes";
}
else
{
cost[i] = 3.98;
item[i]="Hydro Tomatoes";
}
amount[i]=cost[i]*quantity[i];
costout=df2.format(cost[i]);
amountout=df2.format(amount[i]);
line_output=line_output+item[i]+" "+costout+" "+amountout+"\n";
grandtotal=grandtotal + amount[i];
}//for loop
grandtotalout=df2.format(grandtotal);
output=line_output+"\n"+ "The total grocery bill = "+grandtotalout;
JOptionPane.showMessageDialog(null, output, " ", JOptionPane.INFORMATION_MESSAGE);
System.exit(0);
}//main
We are expected to add the classes
class grocery {
}
class printbill{
}
I tried messing with the extends function but I dont think that is correct either

As a starter, your grocery class would look something like this:
final class Grocery
{
Grocery(String InputItem, double InputCost, double InputQuantity)
{
Item = InputItem;
Cost = InputCost;
Quantity = InputQuantity;
}
public final String GetItem()
{
return Item;
}
public final double GetCost()
{
return (double)InputQuantity * Cost;
}
private final String Item;
private final double Cost;
private final int Quantity;
}
The PrintBill class may go like this:
final class PrintBill
{
PrintBill(Grocery [] InputGroceries)
{
Groceries = InputGroceries;
}
public final void Print()
{
double Cost, TotalCost = 0.0;
String Line = "";
String Item;
for (int i = 0; i < Groceries.length; i++)
{
Cost = Groceries[i].GetCost();
Item = Groceries[i].GetItem();
TotalCost += Cost;
// I'll leave it up to you to print this info out.
Line = Item + " " + Cost +" "+ TotalCost +"\n";
}
JOptionPane.showMessageDialog(null, output, " ",
JOptionPane.INFORMATION_MESSAGE);
}
private final Grocery [] Groceries;
}
Your main() would then be:
public static void main(String[] args)
{
String squantity, snumber, output, line_output = "";
Grocery [] Groceries = new Grocery [4];
PrintBill TheBill;
int number;
for (int i = 0; i < Groceries.length; i++)
{
output = " Acme Grocery Store" + "\n" +
"1-Green Beans $0.35 per pound" + "\n" +
"2-Yellow Beans $0.40 per pound" + "\n" +
"3-Head Lettuce $0.79 per pound" + "\n" +
"4-Leaf Lettuce $1.98 per pound" + "\n" +
"5-Hot House Tomatoes $0.99 per pound" + "\n" +
"6-Hydro Tomatoes $3.98 per pound" + "\n" + "\n" +
"Please make your selection ";
snumber = JOptionPane.showInputDialog(null,
output, "Input Data", JOptionPane.QUESTION_MESSAGE);
number = Integer.parseInt(snumber);
squantity = JOptionPane.showInputDialog(null,
"Enter Quantity", "Input Data", JOptionPane.QUESTION_MESSAGE);
quantity = Double.parseDouble(squantity);
if(number == 1)
{
Groceries[i] = new Grocery("Green Beans", 0.35, quantity);
}
else if(number == 2)
{
Groceries[i] = new Grocery("Yellow Beans", 0.4, quantity);
}
// etc...
}
TheBill = new PrintBill(Groceries);
TheBill.Print();
}
More work is required to actually complete this but it should give you a starting point anyway.
Happy Days :-)

Running a Java file from Eclipse on Mac

I'm writing a simple Java program for my history final project and am having trouble exporting it out of eclipse so it can be run on my teacher's computer (a Mac).
Here is the code:
package project;
import java.util.Scanner;
public class Denim {
public static void main(String []args) {
Scanner scan = new Scanner(System.in);
System.out.println("What item of denim is in question?");
String str = scan.nextLine();
String str1 = str.toUpperCase();
String jeans = "JEANS";
String jeansp = "JEAN PANTS";
String tux = "CANADIAN TUXEDO";
String tux1 = "CANADIEN TUXEDO";
String tux2 = "CANADIAN TUX";
String tux3 = "CANADIEN TUX";
String jacket = "JACKET";
String jjacket = "JEAN JACKET";
String hat = "HAT";
String dhat = "DENIM BASEBALL HAT";
String bhat = "BASEBALL HAT";
String c = "C";
int jeanFactor = 9982;
double jacketFactor = 10466.25178;
double bottleFactor = 128/16.9;
double hatFactor = 314.1415;
if (str1.equals(jeans) || str1.equals(jeansp)){
System.out.println("How many pairs of jeans?");
int numj = scan.nextInt();
int gallonj = numj*jeanFactor;
System.out.println("Producing " + numj + " pairs of jeans would use: ");
System.out.println(gallonj + " gallons of water");
double bottlesj = gallonj*bottleFactor;
System.out.println(bottlesj + " bottles of water");}
else if ((str1.equals(tux)) || (str1.equals(tux1)) || (str1.equals(tux2)) ||(str.equals(tux3))){
System.out.println("How many tuxedos?");
int numt = scan.nextInt();
int gallontp = numt * jeanFactor;
double gallontj = numt * jacketFactor;
double gallont = gallontp + gallontj;
double bottlest = gallont*bottleFactor;
System.out.println("Producing " + numt +" " + c + str.substring(1,8) + " tuexedos would use: ");
System.out.println(gallont +" gallons of water.");
System.out.println(bottlest + " bottles of water");}
else if (str1.equals(jacket) || str.equals(jjacket)){
System.out.println("How many jackets?");
int numjj = scan.nextInt();
double gallonjj = numjj*jacketFactor;
double bottlesjj = numjj*bottleFactor;
System.out.println("Producing " + numjj + " jackets would use: ");
System.out.println(gallonjj + " gallons of water");
System.out.println(bottlesjj + " bottles of water");}
else if (str1.equals(hat) || str.equals(dhat) || str.equals(bhat)){
System.out.println("How many hats?");
int numh = scan.nextInt();
double gallonh = numh*hatFactor;
double bottlesh = numh*bottleFactor;
System.out.println("Producing " + numh + " jackets would use: ");
System.out.println(gallonh + " gallons of water");
System.out.println(bottlesh + " bottles of water");
}
}
}
I click file-export and export it as a .jar file, but every time I try and open it to run it, a message pops up saying "The Java JAR file could not be launched. Does anyone know how to fix this or what I'm doing wrong? Both my computer and my teacher's are Macbooks.

Passing method information

Can anyone help me with this problem?
import java.util.*;
public class PaintCalculator
{
public static void main(String[] args)
{
double length;
double width;
double height;
Scanner input = new Scanner(System.in);
System.out.print("Enter the length in feet: ");
length = input.nextDouble();
System.out.print("Enter the width in feet: ");
width = input.nextDouble();
System.out.print("Enter the height in feet: ");
height = input.nextDouble();
System.out.println();
PtinSqFt(length,width,height);
System.out.println("The Cost of a " + length + "- by " + width + "-foot room with a " + height + "-foot ceilings is " + newAmount + "$");
}
public static double PtinSqFt(double v1, double v2, double v3)
{
double GoP = v1*v2*v3;
double newAmount;
newAmount = GallonsOfPaint(GoP)*32;
System.out.println("The wall area for the room is " + GoP + " Square Feet!");
System.out.println("You will need " + GallonsOfPaint(GoP) + " gallons of paint!");
System.out.println("The Cost of a " + v1 + "- by " + v2 + "-foot room with a " + v3 + "- foot ceilings is " + newAmount + "$");
return newAmount;
}
public static double GallonsOfPaint(double GoP)
{
final double SQFT_OF_RM = 350;
double newgallons = (GoP/SQFT_OF_RM);
return newgallons;
}
}
It won't compile when I try to pull the return info from my PtinSqFt method?

You need to store return value of PtinSqFt(length,width,height); in a variable if you want to use it later in your println statement.
So change this
PtinSqFt(length,width,height);
to
double newAmount = PtinSqFt(length,width,height);
and it should work.

Java project returning null values

Hi I am new to Java programming. Why are my values returning null after I enter them on the input dialog. I have two classes, one called VehicleApp and the other called VehicleFactory. Help would be appreciated. Thanks.
Full code VehicleApp.java
package romprojectname;
import java.text.NumberFormat;
import javax.swing.JOptionPane;
public class VehicleApp{
public static void main(String[] args) {
String firstname = JOptionPane.showInputDialog("Enter your first name");
String lastname = JOptionPane.showInputDialog("Enter your last name");
long phone = Long.parseLong(JOptionPane.showInputDialog("Enter your phone"));
int nbrVehicles = Integer.parseInt(JOptionPane.showInputDialog("Enter number of vehicles"));
int nbrTanks = Integer.parseInt(JOptionPane.showInputDialog("Enter number of tanks"));
VehicleFactory vehicleObject = new VehicleFactory();
vehicleObject.getSummary();
vehicleObject.HayloFactory(firstname, lastname, phone, nbrVehicles, nbrTanks);
vehicleObject.calcFuelTankCost();
vehicleObject.calcManufacturingCost();
vehicleObject.calcSubtotal();
vehicleObject.calcTax();
vehicleObject.calcTotal();
}
}
Full code VehicleFactory.java
package romprojectname;
import java.text.NumberFormat;
import javax.swing.JOptionPane;
public class VehicleFactory{
private String firstname;
private String lastname;
private Long phone;
private int nbrVehicles =0;
private int nbrTanks =0;
private double manufactureCost =0;
private double fuelTankCost =0;
private double subtotal =0;
private double tax =0;
private double total = 0;
private final double VEHICLE_PRICE = 500.19;
private final double FUELCELL_PRICE = 2.15;
private final int CELLS_PER_TANK = 12;
private final double taxrate = 7.25 / 100 ;
public void HayloFactory(String firstname, String lastname, Long phone, int nbrVehicles, int nbrTanks){
this.firstname = firstname;
this.lastname = lastname;
this.phone = phone;
this.nbrVehicles = nbrVehicles;
this.nbrTanks = nbrTanks;
}
public void calcManufacturingCost(){
double manufactureCost = nbrVehicles * VEHICLE_PRICE;
}
public void calcFuelTankCost(){
double fuelTankCost = nbrVehicles * nbrTanks * CELLS_PER_TANK * FUELCELL_PRICE;
}
public void calcSubtotal(){
double subtotal = manufactureCost + fuelTankCost;
}
public void calcTax(){
double tax = subtotal * taxrate;
}
public void calcTotal(){
double total = subtotal + tax;
}
NumberFormat cf = NumberFormat.getCurrencyInstance();
public void getSummary(){
String summary = "WELCOME TO HAYLO MANUFACTURING" + "\n" + "\n";
summary += "Customer Name: " + firstname + " " + lastname + "\n";
summary += "Customer Phone: " + phone + "\n";
summary += "Number of Vehicles: " + nbrVehicles + "\n";
summary += "Number of Tanks: " + nbrTanks + "\n";
summary += "Vehicle Cost ($500.19 / vehicle): " + cf.format(manufactureCost) + "\n";
summary += "Tanks Cost ($2.15 / fuel cell): " + cf.format(fuelTankCost) + "\n";
summary += "Subtotal: " + cf.format(subtotal) + "\n";
summary += "Tax (7.25%): " + cf.format(tax) + "\n";
summary += "Total: " + cf.format(total) + "\n";
//display the summary
JOptionPane.showMessageDialog(null, summary);
}
}
Problem (code taken from VehicleFactory.java)
All of the summaries such as customer name are returning null values and all the costs and totals are $0.00.
public void getSummary(){
String summary = "WELCOME TO HAYLO MANUFACTURING" + "\n" + "\n";
summary += "Customer Name: " + firstname + " " + lastname + "\n";
summary += "Customer Phone: " + phone + "\n";
summary += "Number of Vehicles: " + nbrVehicles + "\n";
summary += "Number of Tanks: " + nbrTanks + "\n";
summary += "Vehicle Cost ($500.19 / vehicle): " + cf.format(manufactureCost) + "\n";
summary += "Tanks Cost ($2.15 / fuel cell): " + cf.format(fuelTankCost) + "\n";
summary += "Subtotal: " + cf.format(subtotal) + "\n";
summary += "Tax (7.25%): " + cf.format(tax) + "\n";
summary += "Total: " + cf.format(total) + "\n";
//display the summary
JOptionPane.showMessageDialog(null, summary);

You haven't really described the problem, but I suspect this is the cause:
VehicleFactory vehicleObject = new VehicleFactory();
vehicleObject.getSummary();
vehicleObject.HayloFactory(firstname, lastname, phone, nbrVehicles, nbrTanks);
You're calling getSummary before you call HayloFactory - so it's trying to display the values in the object before you've set them to useful values.
Additionally, all your calcXyz methods are introducing new local variables, like this:
public void calcTotal(){
double total = subtotal + tax;
}
Instead, they should be setting the field values:
public void calcTotal(){
total = subtotal + tax;
}
If you change all of your calculation methods appropriately, then move the getSummary() call to the very end, it will work. (It's not quite how I'd have written the code, but that's a different matter.)

The variables defined insides your methods have local scope only for example
double manufactureCost = nbrVehicles * VEHICLE_PRICE; it actually hides your class variable manufactureCost .. they should be instead used as
manufactureCost = nbrVehicles * VEHICLE_PRICE;
This way you can actually set the class variable which in turn displayed inside your getSummary method

Java - How to print values to 2 decimal places

I'm coding a simulation of a sports game, and it works fine for the most part; compiles and runs like it should. The directions ask that I I assume that I am supposed to be using printf and %.2f, but whenever I try to incorporate that into my code, it ceases to run properly. Help would be much appreciated!
import java.util.Scanner;
public class Team {
public String name;
public String location;
public double offense;
public double defense;
public Team winner;
public Team(String name, String location) {
this.name = name;
this.location = location;
this.offense = luck();
this.defense = luck();
}
public double luck() {
return Math.random();
}
Team play(Team visitor) {
Team winner;
double home;
double away;
home = (this.offense + this.defense + 0.2) * this.luck();
away = (visitor.offense + visitor.defense) * visitor.luck();
if (home > away)
winner = this;
else if (home < away)
winner = visitor;
else
winner = this;
return winner;
}
public static void main(String[] args) {
Scanner s = new Scanner(System.in);
System.out.println("Enter name and location for home team (on separate lines)");
String homeName = s.next();
String homeLocation = s.next();
Team homeTeam = new Team(homeName, homeLocation);
System.out.println("Enter name and location for home team (on separate lines)");
String awayName = s.next();
String awayLocation = s.next();
Team awayTeam = new Team(awayName, awayLocation);
Team winnerTeam = homeTeam.play(awayTeam);
System.out.printf("Home team is:" + homeName + " from" + homeLocation + " rated" + homeTeam.offense + " (offense) +" + homeTeam.defense + " (defense)" + "\n");
System.out.printf("Away team is:" + awayName + " from" + awayLocation + " rated" + awayTeam.offense + " (offense) +" + awayTeam.defense + " (defense)" + "\n");
System.out.printf("Winner is:" + winnerTeam.name + " from" + winnerTeam.location + " rated" + winnerTeam.offense + " (offense) +" + winnerTeam.defense + " (defense)" + "\n");
}

You have misunderstood the printf method. You do not concatenate strings the way you do in this line and its successors (reformatted for width reasons):
System.out.printf("Home team is:" + homeName +
" from" + homeLocation +
" rated" + homeTeam.offense +
" (offense) +" + homeTeam.defense +
" (defense)" + "\n");
This is like the way an old coworker tried to use PreparedStatements to prevent SQL injection attacks, but constructed the query string by concatenation anyway, making the attempt ineffective. Instead, look at the signature of printf:
public PrintWriter format(String format, Object... args)
The first argument is a format string, which contains static text and format directives beginning with %. In typical use, each format directive corresponds to one argument of the method. Replace the interpolated variables with directives.
Strings are usually formatted with %s: s for string. Doubles are usually formatted with %f: f for float (or double). Characters between the % and the letter are options. So, let's replace the strings you interpolated with directives:
"Home team is: " + "%s" + // Inserted a space.
" from" + "%s" +
" rated" + "%6.2f" + // Six characters, 2 after the decimal.
" (offense) +" + "%6.2f" +
" (defense)" + "%n" // %n means the appropriate way to get a new line
// for the encoding.
Now we put it all together:
System.out.format("Home team is: %s from %s rated %6.2f (offense) + %6.2f (defense)%n",
homeName, homeLocation, homeTeam.offense, homeTeam.defense);
This is a lot simpler. Additionally, another reason to avoid interpolating strings in a format string is that the strings you interpolate may contain a percent sign itself. See what happens if you unguardedly write this:
String salesTax = "5%";
System.out.format("The sales tax is " + salesTax);
That's equivalent to
System.out.format("The sales tax is 5%");
Unfortunately, the percent sign is treated as a format directive, and the format statement throws an exception. Correct is either:
System.out.format("The sales tax is 5%%");
or
String salesTax = "5%";
System.out.format("The sales tax is %s", salesTax);
But now I should ask why you did not take homeName and homeLocation from Team. Certainly they are more relevant to Team than to each other. In fact, you should look up the Formattable interface, and with proper coding you can write:
System.out.format("%s%, homeTeam);

Try this:
public class A {
public static void main(String[] args) {
System.out.println(String.format("%.2f", 12.34123123));
}
}