Hi, I'm trying to build an application that functions like a shopping cart system that resembles this dialogue box below. I have it all set up, but I keep getting errors everytime I try to run it. Can you help find the issue? Thanks.

//Here is my code.

import java.awt.BorderLayout;

import java.awt.Font;

import java.awt.GridLayout;

import java.awt.List;

import java.io.File;

import java.io.FileNotFoundException;

import java.text.DecimalFormat;

import java.util.Scanner;

import javax.swing.BorderFactory;

import javax.swing.JButton;

import javax.swing.JFrame;

import javax.swing.JLabel;

import javax.swing.JList;

import javax.swing.JOptionPane;

import javax.swing.JPanel;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

public class ShoppingCart extends JFrame {

private static JPanel listPanel;

private static JPanel shoppingcartPanel;

private static JPanel buttonsPanel;

private static JList listItems;

private static JButton addButton;

private static JButton removeButton;

private static JButton clearButton;

private static JButton checkOutButton;

private static String[] listArray;

private static List cartItems = new List();

// value for salestax

final double salesTax = 0.06;

public ShoppingCart() throws FileNotFoundException {

//Title of the frame

setTitle("Course Scheduling System");

//set the frame exit on close button

setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

//frame layout with 1 row and 3 columns

setLayout(new GridLayout(1, 3));

//position of the frame is set at center of the dialogue box

setLocationRelativeTo(null);

//calling buildListPanel method to create list panel

buildListPanel();

//calling buildListPanel method to create a button panel

buildButtonPanel();

//calling buildCartPanel method to create a cart panel

buildCartPanel();

//adds the panel components to frame

add(listPanel);

add(buttonsPanel);

add(shoppingcartPanel);

pack();

//frame is visible

setVisible (true);

}

private void buildButtonPanel() {

buttonsPanel = new JPanel();

//set layout as GridLayout

buttonsPanel.setLayout(new GridLayout(4, 1));

addButton = new JButton ("Add To Cart");

//add action listener to the addButton

addButton.addActionListener(new AddButtonListener());

removeButton = new JButton("Remove From Cart");

//Add action listener to the removeButton

removeButton.addActionListener(new RemoveButtonListener());

clearButton=new JButton("Clear Cart");

//add action listener to the clearButton

clearButton.addActionListener(new clearButtonListener());

checkOutButton = new JButton ("Check Out");

//add action listener to the checkout button

checkOutButton.addActionListener(new CheckoutButtonListener());

//add buttons to the buttonPanel

buttonsPanel.add(addButton);

buttonsPanel.add(removeButton);

buttonsPanel.add(clearButton);

buttonsPanel.add(checkOutButton);

}

public class AddButtonListener implements ActionListener {

public void actionPerformed(ActionEvent arg0) {

// sprinkle more items from list items

String value = (String) listItems.getSelectedValue();

cartItems.add(value);

}

}

// method implements remove button action listener

public class RemoveButtonListener implements ActionListener {

public void actionPerformed(ActionEvent e) {

// remove items from list items

String str = cartItems.getSelectedItem();

cartItems.remove(str);

}

}

// method removes all items added to the cart list

public class clearButtonListener implements ActionListener {

public void actionPerformed(ActionEvent e) {

cartItems.removeAll();

}

}

// method sprinkles more Label and List Components

private void buildCartPanel() {

shoppingcartPanel = new JPanel();

shoppingcartPanel.setLayout(new BorderLayout());

shoppingcartPanel.setBorder(BorderFactory.createEtchedBorder());

JLabel cartLbl = new JLabel("Cart");

cartLbl.setFont(new Font("Times New Roman", Font.BOLD, 18));

shoppingcartPanel.add(cartLbl, BorderLayout.NORTH);

shoppingcartPanel.add(cartItems, BorderLayout.CENTER);

}

// subtotal all book titles plus sales tax

public class CheckoutButtonListener implements ActionListener {

public void actionPerformed(ActionEvent e) {

String line;

double totalCost = 0;

double costofItem = 0;

File file = new File("BookPrices.txt");

Scanner fileReader = null;

try {

fileReader = new Scanner(file);

} catch (FileNotFoundException e1) {

e1.printStackTrace();

}

while (fileReader.hasNext()) {

line = fileReader.nextLine();

String[] cost = line.split(",");

String title = cost[0];

costofItem = Double.parseDouble(cost[1]);

for (int i = 0; i

if (title.equals(cartItems.getItem(i)))

totalCost += costofItem;

}

}

// calculate tax amount for total cost

double tax = salesTax * totalCost;

DecimalFormat myFormatter = new DecimalFormat("###.##");

// display the total cost in message box

JOptionPane.showMessageDialog(null, "Total Cost is:" + myFormatter.format(tax + totalCost));

}

}

// method creates the list panel with one list

private void buildListPanel() throws FileNotFoundException {

listPanel = new JPanel();

listPanel.setLayout(new BorderLayout());

listPanel.setBorder(BorderFactory.createEtchedBorder());

// set label text

JLabel label = new JLabel("Select A Book Title");

// set bold font

label.setFont(new Font("Times New Roman", Font.BOLD, 18));

String line;

String[] tempArray=new String[100];

int index = 0;

// read book titles from txt file

File file = new File("BookPrices.txt");

Scanner fileReader = new Scanner(file);

// read file title

while (fileReader.hasNext()) {

line = fileReader.nextLine();

String[] titles = line.split(",");

tempArray[index] = titles[0];

index++;

}

//Initialize listArray to be of length=index

//because now index represents number of lines in a file

listArray=new String[index];

//Add titles to listArray

for(int i=0;i

listArray[i]=tempArray[i];

}

// add titles of book

listItems = new JList(listArray);

// set list panel north side

listPanel.add(label, BorderLayout.NORTH);

// set list panel north with list items

listPanel.add(listItems, BorderLayout.CENTER);

}

// method for program execution

public static void main(String[] args) throws FileNotFoundException {

new ShoppingCart();

}

}

Shopping Cart System Select A Book Title Did It Your Way The History of Scotland Learn Calculus in One Day Feel the Stress Great Poems Europe on a Shoestring The Life of Mozart Cart | Learn Calculus in One Da The History of Scotland Add To Cart Remove From Cart Clear Cart Check Out