我有一个类ShoppingCart，它使用ArrayList方法来执行程序，该程序基本上是一个程序，您可以在其中添加杂货到您的购物车等。但是，我想使用数组来代替ArrayLists来执行程序，因为我想处理我的数组知识。这是ShoppingCart类
import java.util.*;
@SuppressWarnings("serial")
public class ShoppingCart extends ArrayList<Selections> {
// FIELDS
private boolean discount;
// Selections[]......
// CONSTRUCTOR
public ShoppingCart() {
super();
discount = false;
}
// Adding to the Collection
public boolean add(Selections next) {
// check to see if it's already here
for (int i = 0; i < this.size(); i++)
if (get(i).equals(next)) {
set(i, next); // replace it
return true;
}
super.add(next); // add new to the array
return false;
}
// The GUI only know if check is on or off
public void setDiscount(boolean disc) {
discount = disc; // match discount from GUI
}
// total of selections
public double getTotal() {
double sum = 0.0;
for (int i = 0; i < this.size(); i++)
sum += get(i).priceFor();
if (discount) sum *= 0.9;
return sum;
}
}
用于个别杂货的选择类。
import java.text.*;
// W.P. Iverson, instructor
// January 2018 for CS211
// Class that combines Item and ItemOrder
public class Selections {
// FIELDS
private String name; // friendly name
private double price; // cost of one
private int bulkQuantity; // when bulk price kicks in
private double bulkPrice; // price for the bulk quantity
private int quantity; // how many we are buying
private boolean hasBulk; // internally used
private NumberFormat curr; // for nice $12.34 currency formatting
// CONSTRUCTORS
public Selections(String name, double price) {
this(name, price, -99999, 99999.); // flag that nothing is selected with 99999
}
public Selections(String thing, double amount, int qty, double bulk) {
name = thing;
price = amount;
if (qty > 0) hasBulk = true;
bulkQuantity = qty;
bulkPrice = bulk;
quantity = 0; // starts with zero selected by user, GUI changes it later
curr = NumberFormat.getCurrencyInstance();
}
// decides how many we're buying
public void setQuantity(int number) {
quantity = number;
}
// calculates the price for this quantity
public double priceFor() {
if (hasBulk && quantity >= bulkQuantity)
return quantity / bulkQuantity * bulkPrice + quantity % bulkQuantity * price;
else
return quantity * price;
}
// basic output for console or GUI text
public String toString() {
if (hasBulk)
return name + ", " + curr.format(price) + " (" + bulkQuantity + " for " + curr.format(bulkPrice) + ")";
else
return name + ", " + curr.format(price);
}
}
我已经为程序创建了一个JFrame，但只是想让它使用常规数组！谢谢你的帮助。
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.text.*;
@SuppressWarnings("serial")
public class ShoppingFrame extends JFrame {
private ShoppingCart items;
private JTextField total;
public ShoppingFrame(Selections[] array) {
// create frame and order list
setTitle("CS211 Shopping List");
setDefaultCloseOperation(EXIT_ON_CLOSE);
items = new ShoppingCart();
// 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(array.length, 1));
for (int i = 0; i < array.length; i++)
addItem(array[i], p);
add(p, BorderLayout.CENTER);
p = new JPanel();
add(makeCheckBoxPanel(), BorderLayout.SOUTH);
// adjust size to just fit
pack();
}
// 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) {
items.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 Selections 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(Selections 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;
}
product.setQuantity(number);
items.add(product);
updateTotal();
}
// reset the text field for order total
private void updateTotal() {
double amount = items.getTotal();
total.setText(NumberFormat.getCurrencyInstance().format(amount));
}
public static void main(String[] args) {
Selections[] array = new Selections[10];
array[0] = new Selections("silly putty", 3.95, 10, 19.99);
array[1] = new Selections("silly string", 3.50, 10, 14.95);
array[2] = new Selections("bottle o bubbles", 0.99);
array[3] = new Selections("Nintendo Wii system", 389.99);
array[4] = new Selections("Mario Computer Science Party 2 (Wii)", 49.99);
array[5] = new Selections("Don Knuth Code Jam Challenge (Wii)", 49.99);
array[6] = new Selections("Computer Science pen", 3.40);
array[7] = new Selections("Rubik's cube", 9.10);
array[8] = new Selections("Computer Science Barbie", 19.99);
array[9] = new Selections("'Java Rules!' button", 0.99, 10, 5.0);
ShoppingFrame f = new ShoppingFrame(array);
f.setVisible(true);
}
}
答案 0 :(得分：0)
您可以在ShoppingCart类中使用数组成员变量，如下所示：
private Selections[] selectionsArray;
而不是扩展ArrayList<Selections>。 （然后你必须自己处理调整阵列的大小。）