the problem set asks me to create a bunch of methods in a class Debt.
The method printBalance prints the current balance, and the waitOneYear method grows the debt amount.
The debt is increased by multiplying the balance by the interest rate.
The program should output
120000.0 ,
121200.0 ,
147887.0328416936
after using this test code:
Debt mortgage = new Debt(120000.0, 1.01);
mortgage.printBalance();
mortgage.waitOneYear();
mortgage.printBalance();
int years = 0;
while (years < 20) {
mortgage.waitOneYear();
years = years + 1;
}
mortgage.printBalance();
The code on my Debt class is:
private double balance;
private double interestRate;
public Debt(double initialBalance, double initialInterestRate) {
balance = initialBalance;
interestRate = initialInterestRate;
}
public void printBalance(){
System.out.println(balance);
}
public void waitOneYear(){
this.balance = this.balance + (this.balance*(this.interestRate/100));
}
I'm getting the first 2 integer values from test code correct, however my third value is coming out to be 148194.8253662062.
Can anyone help?
It is a floating point error. This is a good read on the topic https://dzone.com/articles/never-use-float-and-double-for-monetary-calculatio
This is why when dealing with currencies in Java you MUST always use BigDecimal
Here is your code converted to use BigDecimal.
static class Debt {
private BigDecimal balance;
private BigDecimal interestRate;
Debt(double initialBalance, double initialInterestRate) {
balance = BigDecimal.valueOf(initialBalance);
interestRate = BigDecimal.valueOf(initialInterestRate);
}
public void printBalance() {
System.out.println(balance.setScale(10, RoundingMode.HALF_UP));
}
public void waitOneYear() {
this.balance = this.balance.add(this.balance.multiply(this.interestRate.divide(BigDecimal.valueOf(100), RoundingMode.HALF_DOWN)));
}
}
public static void main(String[] args) {
Debt mortgage = new Debt(120000.0, 1.01);
mortgage.printBalance();
mortgage.waitOneYear();
mortgage.printBalance();
int years = 0;
while (years < 20) {
mortgage.waitOneYear();
years = years + 1;
}
mortgage.printBalance();
}
Related
I am getting an error that says: C:\Users\Jasmi\payroll\src\Payroll.java:68:38
java: variable grossPay might not have been initialized, but I am not sure how to fix it.
public class Payroll {
public String calculateGrossPay;
public String calculateNetPay;
private String name;
private int idNumber;
private double hourlyPayRate;
private double hoursworked;
Payroll(String nameGiven, int idNumbergiven) {
name = nameGiven;
idNumber = idNumbergiven;
hourlyPayRate = 7.15;
hoursworked = 0;
}
public String getName() {
return name;
}
public int getIDNumber() {
return idNumber;
}
public double getHourlyPayrate() {
return hourlyPayRate;
}
public double getHoursWorked() {
return hoursworked;
}
public void setName(String nameGiven) {
name = nameGiven;
}
public void setIDNumber(int idNumbergiven) {
idNumber = idNumbergiven;
}
public void setHourlyPayRate(double hourlypayrategiven) {
hourlyPayRate = hourlypayrategiven;
}
public void setHoursWorked(double hoursworkedgiven) {
hoursworked = hoursworkedgiven;
}
//gross pay plus overtime
public double calculateGrossPay() {
double overtime;
overtime = 0;
double grossPay;
if (hoursworked < 40) grossPay = hourlyPayRate * hoursworked;
else {
overtime = hoursworked - 40;
grossPay = (overtime * 1.5 * hourlyPayRate) + (40 * hourlyPayRate);
}
return grossPay;
}
//deductions
public double calculateNetPay() {
double netPay;
double grossPay;
double deduction = (.2579) * grossPay;
return netPay;
}
}
Here is the second document:
import javax.swing.JOptionPane;
public class PayrollClassTest {
public static void main(String[] args) {
String userInputString;
String userName;
int userId;
double userhourlyPayRate;
double userHoursworked;
userName = JOptionPane.showInputDialog("enter the name of this employee: ");
userInputString = JOptionPane.showInputDialog("Please enter employee ID: ");
userId = Integer.parseInt(userInputString);
userInputString = JOptionPane.showInputDialog("Please enter Hourly Pay Rate: ");
userhourlyPayRate = Double.parseDouble(userInputString);
userInputString = JOptionPane.showInputDialog("Enter the hours worked: ");
userHoursworked = Double.parseDouble(userInputString);
Payroll payroll1 = new Payroll(userName, userId);
payroll1.setHourlyPayRate(userhourlyPayRate);
payroll1.setHoursWorked(userHoursworked);
System.out.println(payroll1.getName() + " has a gross pay of " + payroll1.calculateGrossPay());
System.out.println(payroll1.getName() + " has a net pay of " + payroll1.calculateNetPay());
System.exit(0);
}
private static void calculateGrossPay() {
}
private static void calculateNetPay() {
}
}
I have tried to change deductions to be shown as this:
//deductions
public double calculateNetPay() {
double netPay = 0;
double grossPay = 0;
double deduction = (.2579) * grossPay;
return netPay;
}
}
It does work, but the results do not show the deductions:
Here is an example of the results:
Betty has a gross pay of 13000.0
Betty has a net pay of 0.0
Process finished with exit code 0
This is when I put name as Betty, gross pay as 100, and hours worked as 100. It shows the overtime correctly, but not the deductions.
Any help is greatly appreciated. thanks!
If my understanding of the code is correct then the following is where you are wrong for this piece of code.
public double calculateNetPay() {
double netPay = 0;
double grossPay = 0;
double deduction = (.2579) * grossPay;
return netPay;
}
First: netPay has no value assigned
This method will always return 0.
Reason : The netPay variable is declared and initialized to 0.
What you probably want to do before your return statement is perhaps;
netPay = grossPay - deduction;
I could be wrong in that logic, but I am definitely right when I say that you need to put some value to netPay before you return it.
Second: grossPay has no value assigned
In this method, you multiple .2579 with grossPay, but grossPay is 0 that you have now initialized.
You are assuming that the variable grossPay is shared for the two methods calculateGrossPay and calculateNetPay.
That is not true.
These are both two separate local variables that are declared separately in two different methods and have two different scopes.
You can read more about scope of java variables here:
variable docs from oracle
"in scope" meaning in java : StackOverflow question
My recommendation is to make grossPay a class variable instead of a method variable so that it could be shared between the two methods of the same class instance. (Assuming you are calling calculateGrossPay before calculateNetPay every time, so that grossPay can have the right value assigned to it.)
I would like someones expert opinion on both of my account class and the test account interest class. The issue I am facing is that the code from the test account interest class just multiplies on from the previous 12 month compute interest when it is supposed to be used only once.
The issue is in the
public double computeInterest(int n)
{
balance=balance*(Math.pow((1+rate),n/12));
return balance;
}
It is in this method of where the problem is that I should not use the balance but to use a variable that will store the answer but I did not understand the person that very clearly and he was very vague by only stating a variable should be used.
public class Account
{
private double balance; //STATE
private double interestRate; //STATE
private double rate;//STATE
public Account()
{
balance = 0;
interestRate = 0;
}
public Account(double amount, double interestRate)
{
balance = amount;
rate = interestRate;
}
public void deposit(double amount)
{
balance=balance+amount;
}
public void withdraw(double amount)
{
balance = balance - amount;
}
public void setInterest(double rate)
{
balance = balance + balance * rate;
//this.setInterst = setInterest;
//setInterest = InterestRate / 12;
}
public double computeInterest(int n)
{
balance=balance*(Math.pow((1+rate),n/12));
return balance;
}
public double getsetInterest()
{
return rate;
}
public double getBalance()
{
return balance;
}
public void close()
{
balance =0;
}
}
This is my test account interest class:
public class TestAccountInterest
{
public static void main (String[] args)
{
Account acc1 = new Account(100, 0.1);//0.10);
Account acc2 = new Account(133, 0.2); //0.20);
/*************************************
ACC1 ACCOUNT BELOW
*************************************/
//acc1.deposit(100);
//acc1.withdraw(100);
System.out.println(acc1.computeInterest(12));
// //acc1.computeInterest(12);
// System.out.println(acc1.computeInterest(24));
/**************************************
ACC2 ACCOUNT BELOW
**************************************/
acc2.withdraw(100);
acc2.deposit(100);
//acc2.computeInterest(24);
System.out.println(acc2.computeInterest(24));
}
}
This is the final output:
110.00000000000001
191.51999999999998
As you can see for the second one the figure is multiplied by the 12 month compute interest with the 24 month compute interest this stems from the method in the account class:
public double computeInterest(int n)
{
balance=balance*(Math.pow((1+rate),n/12));
return balance;
}
If I take out the balance it still causes and error so I confused on this particular part.
Code,
public double computeInterest(int n) {
balance = balance * (Math.pow((1 + rate), n / 12));
return balance;
}
should be changed to
public double computeInterest(int n) {
return balance * Math.pow(1 + rate, n / 12);
}
You shouldn't change balance field while computing interest. You might like to have a separate method to update balance where you do , balance = balance + computed_interest or something like that.
Also, I have remove unnecessary parenthesis. That was not an error but simply making your code less readable.
I'm having a problem which I cannot fathom why. I have program I'm making where it takes a few inputs and calculates pay, tax, and final pay.
Everything is working except the final pay.
this calculates the final pay
import java.util.*;
public class Payroll extends Pay
{
public double calc_payroll()
{
super.calc_payroll();
super.tax();
netPay = grossPay - (grossPay * (tax/100));
return netPay;
}
}
this calculates pay and tax
import java.util.*;
public class Pay
{
private float hoursWrkd;
private float rate;
private int hoursStr;
float grossPay;
int tax;
float netPay;
public double calc_payroll()
{
grossPay = getHoursWrkd()*getRate();
return grossPay;
}
public double tax()
{
if (grossPay <= 399.99)
{
tax = 7;
}
else if (grossPay >= 400.00 && grossPay <= 899.99)
{
tax = 11;
}
else if (grossPay <= 900.00)
{
tax = 15;
}
return tax;
}
//Get & Set for hours worked
public float getHoursWrkd()
{
return hoursWrkd;
}
public void setHoursWrkd(float hoursWrkd)
{
this.hoursWrkd = hoursWrkd;
}
//Get & Set for Rate
public float getRate()
{
return rate;
}
public void setRate(float rate) {
this.rate = rate;
}
//Get & Set for hours straight
public int getHoursStr()
{
return hoursStr;
}
public void setHoursStr(int hoursStr)
{
this.hoursStr = hoursStr;
}
}
and this displays all
public class CalPayroll extends Pay
{
public void displayInfo()
{
super.calc_payroll();
super.tax();
Payroll colio = new Payroll();
colio.calc_payroll();
NumberFormat dollars = NumberFormat.getCurrencyInstance();
System.out.println("Gross Pay is : " + dollars.format(grossPay));
System.out.println("Tax is : " + tax + "%");
System.out.println("Net Pay is : " + dollars.format(netPay));
}
i have more files but those are the ones that just take the input, and call the other files.
The math is correct, however when i try to call the netPay variable and format it, it dosn't display any ammount. With grosspay it works. However my teacher said were supposed to pass grosspay into tax so it can use it, im not sure if that would fix it.
PLease help.
You try to display the netPay from CalPayroll, but this class never computes this value. When you do
Payroll colio = new Payroll();
colio.calc_payroll();
You’re probably expecting the netPay to be calculated in CalPayrool, but you’re actually calculating a separate value in a separate object, which has no effect on the current object.
The code I wrote compiles well, but there are certain values that do not calculate. The rate and hours value, tuition and .08 do not calculate. Maybe my code is wrong or something. I am still new to java so i am trying my best. Here is my code:
import java.io.*;
import java.text.DecimalFormat;
import java.util.Scanner;
public class Tuition
{
static double fees;
static double rate;
static double tuition;
private static Scanner sc;
public static void main(String[] args) throws IOException
{
//declare variables
int hours;
//call methods
displayWelcome();
hours = getHours();
rate = getRate(hours);
tuition = calcTuition(hours, rate);
fees = calcFees(tuition);
}
public static void displayWelcome()
{
//welcome statement
System.out.println("Welcome to school that offers distance learning courses");
}
public static int getHours()
{
//declare method variables
int hours = 0;
//a user must enter a string value
System.out.println("Enter total number of hours");
sc = new Scanner(System.in);
try
{
hours = sc.nextInt();
}
catch(NumberFormatException e)
{
System.out.print("Incorrect number");
}
return hours;
}
public static double getRate(int hours)
{
if (hours > 15)
{
System.out.println("rate per credit hour is 44.50");
}
else
{
System.out.println("rate per credit hour is 50.00");
}
return rate;
}
public static double calcTuition(int hours, double rate)
{
tuition =(double)rate * hours;
System.out.print("tuition is" + (tuition));
return tuition;
}
public static double calcFees(double tuition)
{
fees =(double)tuition * .08;
System.out.print("fees are" + (fees));
return fees;
}
public static void displayToatal(double total)
{
DecimalFormat twoDigits = new DecimalFormat("$#,000.00");
System.out.println("the total value is"+ twoDigits.format(tuition + fees));
}
}
In calcTuition()
tuition =(double)rate * hours;
should be
tuition =rate * (double)hours;
: )
You aren't setting the rate. You need a line of code that looks like "rate = x;". You only have println's in the getRate method, but you don't actually set the variable to equal anything.
This will be my second question on here; I try not to ask because I don't fancy receiving help for my homework. But I'm just plain stuck.
I'm currently writing a program that stores and updates information for some example bank accounts. My issue is that, somehow, my output has two decimal points.
Example:
"2000.02008.3333333333333"
Side notes: I'm in a Tier II java course, so yes, my code isn't the prettiest. Also, please only offer hints as to where I should make changes. As I said earlier, I try really hard not to ask for help and I don't want my request for help to be misconstrued as cheating. Finally, I do know about syso formatting and will be doing that with the Title information in my driver. The way I did it in there was just faster for me at the time while I fleshed out the rest of the details.
Many thanks in advance to any help provided!
Here's my current code:
public class SavingsAccount
{
private static double annualInterestRate;
private final int ACCOUNT_NUMBER;
private double balance;
public SavingsAccount(int ACCOUNT_NUMBER, double balance)
{
this.ACCOUNT_NUMBER = ACCOUNT_NUMBER;
this.balance = balance;
}
public static double setAnnualInterestRate(double aIR)
{
annualInterestRate = aIR;
return annualInterestRate;
}
public int getAccountNumber()
{
return ACCOUNT_NUMBER;
}
public double getBalance()
{
return balance;
}
public double addMonthlyInterest()
{
balance += (balance * annualInterestRate / 12);
return balance;
}
}
DRIVER
public class Chapter13
{
public static void main(String[] args)
{
double annualInterestRate = .05;
SavingsAccount saver1 = new SavingsAccount(10002, 2000);
SavingsAccount saver2 = new SavingsAccount(10003, 3000);
SavingsAccount.setAnnualInterestRate(annualInterestRate);
System.out.println("Month Acount# Balance Account# Balance");
for(int i = 0; i < 13; i++)
{
System.out.println(i + " " + saver1.getBalance() +
saver1.addMonthlyInterest());
}
}
}
That's because the balance and annualInterestRate are getting printed without any space between them. Add a tab or space between them so that they are printed separately.
System.out.println(i + " " + saver1.getBalance() + "\t" // tab
saver1.addMonthlyInterest());
System.out.println(i + " " + saver1.getBalance() + " " // space
saver1.addMonthlyInterest());