我比Java更新，所以我仍然试图了解如何正确更新变量。我正在创建一个充当餐厅菜单的程序。列出的菜单项将显示在左侧，一旦用户检查项目并单击右键，项目将显示在右侧，并且项目的价格应该添加到总变量中;但是，这不起作用。有一些不必要的代码，但如果可以，请忽略这些和一些评论。谢谢。
package finalproject;
import java.awt.event.*;
import java.awt.*;
import javax.swing.*;
public class MenuFrame extends JFrame implements ActionListener {
final double BURGER_PRICE = 6.24;
final double FISH_PRICE = 13.78;
final double SOUP_PRICE = 4.49;
final double CHICKEN_PRICE = 11.36;
final double SALAD_PRICE = 5.60;
final double FRIES_PRICE = 3.24;
JPanel menuPanel = new JPanel(); //Panel to place the menu in, which will be on left side
JPanel buttonPanel = new JPanel(); //Panel to place buttons in, which will be in center
JPanel orderPanel = new JPanel(); //Panel to place order menu in, which will be on right side
JLabel menuLabel = new JLabel("Menu"); //Label for the menu
JLabel orderLabel = new JLabel("Your Order"); //Label for the user's order
JCheckBox burger = new JCheckBox("Burger: $6.24", false); //Burger check box
JCheckBox fish = new JCheckBox("Fish: $13.78", false); //Fish check box
JCheckBox soup = new JCheckBox("Soup: $4.49", false); //Soup check box
JCheckBox chicken = new JCheckBox("Chicken: $11.36", false); //Chicken check box
JCheckBox salad = new JCheckBox("Salad: $5.60", false); //Salad check box
JCheckBox fries = new JCheckBox("Fries: $3.24", false); //Fries check box
JButton rightButton = new JButton("->"); //Button to move items from left to right
JButton leftButton = new JButton("<-"); //Button to move items from right to left
JLabel skipPosition = new JLabel(""); //Label used to skip position in GridLayout
static double totalPrice = 0; //Total price of order
Font titleFont = new Font("Times New Roman",Font.BOLD,20);
JLabel totalLabel = new JLabel(""); //total label
public MenuFrame() {
setLayout(new GridLayout(0,3));
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(1055, 275); //Set size of Menu Frame
menuPanel.setLayout(new GridLayout(0,3)); //Setting Menu's layout to GridLayout
//Box buttonBox = Box.createVerticalBox(); //Creating box object for button panel
buttonPanel.setLayout(new GridLayout(8,3));
orderPanel.setLayout(new GridLayout(0,3)); //Setting Order's layout to FlowLayout
menuLabel.setFont(titleFont);
orderLabel.setFont(titleFont);
//Adding menu items to Menu
menuPanel.add(new JLabel(""));
menuPanel.add(menuLabel);
menuPanel.add(new JLabel(""));
menuPanel.add(burger);
menuPanel.add(fish);
menuPanel.add(soup);
menuPanel.add(chicken);
menuPanel.add(salad);
menuPanel.add(fries);
//Adding buttons to Box
//buttonBox.add(rightButton);
//buttonBox.add(Box.createVerticalStrut(100));
//buttonBox.add(leftButton);
//Adding box to button panel
//buttonPanel.add(buttonBox);
//Adding "Your Order" label to Order. Items will be subsequently added or removed
orderPanel.add(new JLabel(""));
orderPanel.add(orderLabel);
orderPanel.add(new JLabel(""));
totalLabel.setText("$" + totalPrice);
buttonPanel.add(new JLabel(""));
buttonPanel.add(new JLabel(""));
buttonPanel.add(new JLabel(""));
buttonPanel.add(new JLabel(""));
buttonPanel.add(new JLabel(""));
buttonPanel.add(new JLabel(""));
buttonPanel.add(new JLabel(""));
buttonPanel.add(new JLabel(""));
buttonPanel.add(new JLabel(""));
buttonPanel.add(new JLabel(""));
buttonPanel.add(rightButton);
buttonPanel.add(new JLabel(""));
buttonPanel.add(new JLabel(""));
buttonPanel.add(leftButton);
buttonPanel.add(new JLabel(""));
buttonPanel.add(new JLabel(""));
buttonPanel.add(new JLabel(""));
buttonPanel.add(new JLabel(""));
buttonPanel.add(new JLabel(""));
buttonPanel.add(new JLabel(""));
buttonPanel.add(new JLabel(""));
buttonPanel.add(new JLabel(""));
buttonPanel.add(new JLabel(""));
buttonPanel.add(new JLabel(""));
buttonPanel.add(totalLabel);
//Adding action listener to rightButton and leftButton
rightButton.addActionListener(this);
leftButton.addActionListener(this);
add(menuPanel);
add(buttonPanel);
add(orderPanel);
}
@Override
public void actionPerformed(ActionEvent e) {
Object source = e.getSource();
//If right button was clicked
if(source == rightButton) {
//if burger was selected and is in the menu panel
if(burger.isSelected() && burger.getParent() == menuPanel) {
//Move burger from menu to order, deselect burger, and add 6.24 to total price
menuPanel.remove(burger);
orderPanel.add(burger);
burger.setSelected(false);
totalPrice += BURGER_PRICE;
}
//if fish was selected and is in the menu panel
if(fish.isSelected() && fish.getParent() == menuPanel) {
//Move fish from menu to order, deselect fish, and add 13.78 to total price
menuPanel.remove(fish);
orderPanel.add(fish);
fish.setSelected(false);
totalPrice += FISH_PRICE;
}
//if soup was selected and is in the menu panel
if(soup.isSelected() && soup.getParent() == menuPanel) {
//Move soup from menu to order, deselect soup, and add 4.49 to total price
menuPanel.remove(soup);
orderPanel.add(soup);
soup.setSelected(false);
totalPrice += SOUP_PRICE;
}
//if chicken was selected and is in the menu panel
if(chicken.isSelected() && chicken.getParent() == menuPanel) {
//Move chicken from menu to order, deselect chicken, and add 11.36 to total price
menuPanel.remove(chicken);
orderPanel.add(chicken);
chicken.setSelected(false);
totalPrice += CHICKEN_PRICE;
}
//if salad was selected and is in the menu panel
if(salad.isSelected() && salad.getParent() == menuPanel) {
//Move salad from menu to order, deselect salad, and add 5.60 to total price
menuPanel.remove(salad);
orderPanel.add(salad);
salad.setSelected(false);
totalPrice += SALAD_PRICE;
}
//if fries was selected and is in the menu panel
if(fries.isSelected() && fries.getParent() == menuPanel) {
//Move fries from menu to order, deselect fries, and add 3.24 to total price
menuPanel.remove(fries);
orderPanel.add(fries);
fries.setSelected(false);
totalPrice += FRIES_PRICE;
}
}
//if left button was clicked
if(source == leftButton) {
//if burger was selected and is in the order panel
if(burger.isSelected() && burger.getParent() == orderPanel) {
//Move burger from order to menu, deselect burger, and remove 6.24 from total price
orderPanel.remove(burger);
menuPanel.add(burger);
burger.setSelected(false);
totalPrice -= BURGER_PRICE;
}
//if fish was selected and is in the order panel
if(fish.isSelected() && fish.getParent() == orderPanel) {
//Move fish from order to menu, deselect fish, and remove 13.78 from total price
orderPanel.remove(fish);
menuPanel.add(fish);
fish.setSelected(false);
totalPrice -= FISH_PRICE;
}
//if soup was selected and is in the order panel
if(soup.isSelected() && soup.getParent() == orderPanel) {
//Move soup from order to menu, deselect soup, and remove 4.49 from total price
orderPanel.remove(soup);
menuPanel.add(soup);
soup.setSelected(false);
totalPrice -= SOUP_PRICE;
}
//if chicken was selected and is in the order panel
if(chicken.isSelected() && chicken.getParent() == orderPanel) {
//Move chicken from order to menu, deselect chicken, and remove 11.35 from total price
orderPanel.remove(chicken);
menuPanel.add(chicken);
chicken.setSelected(false);
totalPrice -= CHICKEN_PRICE;
}
//if salad was selected and is in the order panel
if(salad.isSelected() && salad.getParent() == orderPanel) {
//Move salad from order to menu, deselect salad, and remove 5.60 from total price
orderPanel.remove(salad);
menuPanel.add(salad);
salad.setSelected(false);
totalPrice -= SALAD_PRICE;
}
//if fries was selected and is in the order panel
if(fries.isSelected() && fries.getParent() == orderPanel) {
//Move fries from order to menu, deselect fries, and remove 3.24 from total price
orderPanel.remove(fries);
menuPanel.add(fries);
fries.setSelected(false);
totalPrice -= FRIES_PRICE;
}
}
//Make changes appear
repaint();
revalidate();
}
public static void main(String[] args) {
//Instantiating MenuFrame object
MenuFrame menuFrame = new MenuFrame();
//Making frame visible
menuFrame.setVisible(true);
}
答案 0 :(得分：0)
如果您不指定totalPrice，则不会将其设置到textField中。 在刷新之前把它放在：
totalLabel.setText("$" + totalPrice);
答案 1 :(得分：0)
变量更新正确，只是您没有重新设置totalLabel文本。
if(burger.isSelected() && burger.getParent() == menuPanel) {
//Move burger from menu to order, deselect burger, and add 6.24 to total price
menuPanel.remove(burger);
orderPanel.add(burger);
burger.setSelected(false);
totalPrice += BURGER_PRICE;
totalLabel.setText("$" + totalPrice); <<<<<< Add this to all of items
}