Homework SourseThese are my four classes I need help with the shoppingCart
These are my four classes, I need help with the shoppingCart class that extends ArrayList<NumSelected> to get it to work. I need to have a super() in my shoppingcart class constructor that is I must not create a new object, just use inheretence. That I can\'t get.
/**
* @author Reges and Stepp, Building Java Programs
* modified by W.P. Iverson, Bellevue College,
* January 2017for CS211 class
*/
// Stuart Reges
// 3/28/07
//
// Class ShoppingFrame provides the user interface for a simple shopping
// program, starting with Building Java Programs, chapter 10, project 1.
//
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.text.*;
import java.util.*;
@SuppressWarnings(\"serial\")
public class ShoppingFrame extends JFrame {
private ShoppingCart selections;
private JTextField total;
public ShoppingFrame(ArrayList<Sku> products) {
// create frame and order list
setTitle(\"CS Gift Catalog\");
setDefaultCloseOperation(EXIT_ON_CLOSE);
selections = new ShoppingCart();
// Just making sure we\'re using the Iverson version:
if (!(selections instanceof ArrayList))
throw new RuntimeException(\"This quarter I require an ArrayList\");
// set up text field with order total
total = new JTextField(\"$0.00\", 12);
total.setEditable(false);
total.setEnabled(false);
total.setDisabledTextColor(Color.BLACK);
JPanel p = new JPanel();
p.setBackground(Color.blue);
JLabel l = new JLabel(\"Order Total\");
l.setForeground(Color.YELLOW);
p.add(l);
p.add(total);
add(p, BorderLayout.NORTH);
p = new JPanel(new GridLayout(products.size(), 1));
removeDuplicates(products);
for (Sku i : products) {
addItem(i, p); // add selections to panel
}
add(p, BorderLayout.CENTER); // add panel to frame
p = new JPanel();
add(makeCheckBoxPanel(), BorderLayout.SOUTH);
// adjust size to just fit
pack();
}
// Should probably use Set rather than Array List, but this is Chapter 10
private void removeDuplicates(ArrayList<Sku> products) {
for (Sku i: products) {
if (products.indexOf(i) != products.lastIndexOf(i))
products.remove(i);
}
}
// Sets up the \"discount\" checkbox for the frame
private JPanel makeCheckBoxPanel() {
JPanel p = new JPanel();
p.setBackground(Color.blue);
final JCheckBox cb = new JCheckBox(\"qualify for discount\");
p.add(cb);
cb.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
selections.setDiscount(cb.isSelected());
updateTotal();
}
});
return p;
}
// adds a product to the panel, including a textfield for user input of
// the quantity
private void addItem(final Sku product, JPanel p) {
JPanel sub = new JPanel(new FlowLayout(FlowLayout.LEFT));
sub.setBackground(new Color(0, 180, 0));
final JTextField quantity = new JTextField(3);
quantity.setHorizontalAlignment(SwingConstants.CENTER);
quantity.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
updateItem(product, quantity);
quantity.transferFocus();
}
});
quantity.addFocusListener(new FocusAdapter() {
public void focusLost(FocusEvent e) {
updateItem(product, quantity);
}
});
sub.add(quantity);
JLabel l = new JLabel(\"\" + product);
l.setForeground(Color.white);
sub.add(l);
p.add(sub);
}
// When the user types a new value into one of the quantity fields,
// parse the input and update the ShoppingCart. Display an error
// message if text is not a number or is negative.
private void updateItem(Sku product, JTextField quantity) {
int number;
String text = quantity.getText().trim();
try {
number = Integer.parseInt(text);
} catch (NumberFormatException error) {
number = 0;
}
if (number <= 0 && text.length() > 0) {
Toolkit.getDefaultToolkit().beep();
quantity.setText(\"\");
number = 0;
}
selections.add(new NumSelected(product, number));
updateTotal();
}
// reset the text field for order total
private void updateTotal() {
double amount = selections.getTotal();
total.setText(NumberFormat.getCurrencyInstance().format(amount));
}
// Below used to be separate ShoppingMain, now an easier entry point:
public static void main(String[] args) {
// the Catalog is a simple Array List of Items:
ArrayList<Sku> list = new ArrayList<Sku>();
list.add(new Sku(\"silly putty\", 3.95, 10, 19.99));
list.add(new Sku(\"silly string\", 3.50, 10, 14.95));
list.add(new Sku(\"bottle o bubbles\", 0.99));
list.add(new Sku(\"Nintendo Wii system\", 389.99));
list.add(new Sku(\"Mario Computer Science Party 2 (Wii)\", 49.99));
list.add(new Sku(\"Don Knuth Code Jam Challenge (Wii)\", 49.99));
list.add(new Sku(\"Computer Science pen\", 3.40));
list.add(new Sku(\"Rubik\'s cube\", 9.10));
list.add(new Sku(\"Computer Science Barbie\", 19.99));
list.add(new Sku(\"\'Java Rules!\' button\", 0.99, 10, 5.0));
list.add(new Sku(\"\'Java Rules!\' bumper sticker\", 0.99, 20, 8.95));
ShoppingFrame f = new ShoppingFrame(list);
f.setVisible(true);
}
import java.util.ArrayList;
public class ShoppingCart extends ArrayList<NumSelected>{
//Create a class variables.
private ArrayList<NumSelected>NumSelected;
private double total = 0;
private double discount = 0;
// Constructor that creates an empty list of orders
public ShoppingCart(){
super();
total = 0;
}
// Boolean method to return true when an item added successfully.
public boolean add(NumSelected yes) {
for(int i =0 ; i<NumSelected.size(); i++){
NumSelected temp = NumSelected.get(i);
if(temp.getSku(i).equals(yes.getSku(i))){
NumSelected.set(i, yes);
return true;
}
}
NumSelected.add(yes);
return true;
}
// Method to return the total cost of the shopping cart.
public double getTotal() {
total = 0;
for(NumSelected yes : NumSelected){
total +=yes.getPrice();
}
return total - discount;
}
// Method to set discount if order gets discount
public void setDiscount(boolean selected) {
if(selected){
discount = total * 0.1;
}
}
}
import java.text.*;
public class Sku {
// To create class variables.
private String name;
private double price;
private int bulkQuantity;
private double bulkPrice;
// Constructor That takes a name and single sku-price and a bulk quantity
// and a bulk price as arguments.
public Sku(String name, double price, int quantity, double bulk) {
this.name = name;
this.price = price;
if(price<0){
throw new IllegalArgumentException(\"price must be positive\");
}
this.bulkQuantity = quantity;
if(quantity<0){
throw new IllegalArgumentException(\"quantity must be positive\");
}
this.bulkPrice = bulk;
if(bulk<0){
throw new IllegalArgumentException(\"bulk price must be positive\");
}
}
// Constructor that takes a name a price as arguments.
public Sku(String name, double price) {
if(price<0){
throw new IllegalArgumentException(\"price must be positive\");
}
this.name =name;
this.price = price;
}
// Method to return the price for the giving quantity.
public double priceFor(int quan){
double first = 0;
if(quan < 0){
throw new IllegalArgumentException(\"price must be positive\");
}
else{
if(bulkQuantity !=0){
first = (quan/bulkQuantity)*bulkPrice + (quan % bulkQuantity)*price;
}
else{
first=quan*price;
}
}
return first;
}
// Return a string representation of sku.
public String toString(){
NumberFormat nf = NumberFormat.getCurrencyInstance();
String s = \"\";
s = name + \",\" + nf.format(price);
if(bulkPrice !=0){
s = name + \",\" + nf.format(price)+
\"(\" + bulkQuantity + \"for\" + nf.format(bulkPrice) + \")\";
}
return s;
}
// Boolean to help if two sku\'s are the same.
public boolean equals(Sku boo){
if(this.name.equals(boo.name)){
return true;
}
return false;
}
}
public class NumSelected {
// Create a class variables.
private Sku product;
private int quantity;
// Constructor that creates an order for the given sku and given quantity.
public NumSelected(Sku product, int quantity) {
this.product = product;
this.quantity = quantity;
}
// Returns the cost for this order.
public double getPrice(){
return product.priceFor(quantity);
}
// Returns a reference (Sku reference) to this order.
public Sku getSku(int i){
return product;
}
}
Solution
Use this
public ShoppingCart(){
total = 0;
}
public ShoppingCart(ArrayList<NumSelected>NumSelected){
super(NumSelected);
total = 0;
}
2. You can also do in this way
What you need is to do is to get the instance of same array list object if its present othrewise get the new instance of it.
public ArrayList<NumSelected> getInstance(){
if(NumSelected==null)
return new ArrayList<NumSelected>();
else
return this.NumSelected; //Same Instance for that we have to make ArrayList object as static so only once //it will be created
}
3. There is one problem in the code:
for (Sku i : products) {
if (products.indexOf(i) != products.lastIndexOf(i))
products.remove(i); //You cannot do this
}
While iterating an array list, If we use remove operation . We will get concurrent Modifcation Exception.
That should be avoided. If we still want to perform that . Then we need to use , the use
CopyOnWriteArrayList.
Thanks, let me know if there is any concern.
