Question

我正在尝试更新totalOrderedLabel，以便当我从orderList中删除一个项目时，totalOrderedLabel中的totalPrice将会更新。

删除按钮

JButton removeButton = new JButton("remove");
    removeButton.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
                int selectionNumber = orderList.getSelectedIndex();
                if (selectionNumber == -1) {
                    JOptionPane.showMessageDialog(MenuPage.this, "Remove Item");
                } else {
                    listOrder.removeElementAt(selectionNumber);

                    double totalPrice = 0.0;
                    for(Food food  : OrderedFoodList) {
                        totalPrice = totalPrice + food.getPrice(); 
                    }

                    totalOrderedLabel.setText("Total price: " + totalPrice);
                    OrderedFoodList.clear();
                }
        }

    });
    removeButton.setBounds(680, 189, 117, 29);
    contentPane.add(removeButton);

orderList /方法来累计总价格。

    menulist listOrder = new menulist();
    orderList = new JList(listOrder);

JButton orderBtn = new JButton();
    orderBtn.setText("Place Order");
    orderBtn.addActionListener(new ActionListener() {

        public void actionPerformed(ActionEvent e) {
            int selectionNumber = mealList.getSelectedIndex();
            if (selectionNumber == -1){
                JOptionPane.showMessageDialog(MenuPage.this, "Please select a meal");
            } else {
                Food orderedMeal = (Food) mealList.getSelectedValue();

                JOptionPane.showMessageDialog(MenuPage.this, "You have ordered "        //clear the last order . find a code to do that
                        + orderedMeal + "");

                listOrder.addElement(orderedMeal);

                double totalPrice = 0.0;
                for(Food food  : OrderedFoodList) {
                    totalPrice = totalPrice + food.getPrice();
                }
                totalOrderedLabel.setText("Total price: " + totalPrice);

                }
        }

    });
    orderBtn.setBounds(259, 189, 117, 29);
    contentPane.add(orderBtn);

totalOrdered Label

totalOrderedLabel = new JLabel("Total Price");
    totalOrderedLabel.setBounds(697, 111, 142, 16);
    contentPane.add(totalOrderedLabel);

    totalCaloriesLabel = new JLabel("Total Calories");
    totalCaloriesLabel.setBounds(388, 205, 253, 16);
    contentPane.add(totalCaloriesLabel);
    }

public void updateLabel(menulist model) {

int selectionNumber = mealList.getSelectedIndex();
if (selectionNumber == -1){
    //JOptionPane.showMessageDialog(MenuPage.this, "Please select a meal");
} else {
    Food menulist = (Food) mealList.getSelectedValue();
Food itemFood = (Food) ((menulist) model).getElementAt(selectionNumber);

//Add new food to current order
OrderedFoodList.add(itemFood);

Answer 1

我正在尝试更新我的totalOrderedLabel，以便当我从orderList中删除一个项目时，totalOrderedLabel中的totalPrice将会更新

当你在列表中添加新项目时呢？在这两种情况下，概念都是相同的，您遍历列表中的所有项目，然后更新标签。

因此，当列表中的项目发生变化时，您需要得到通知。向ListDataListener添加ListModel。然后，当生成事件时，您遍历列表中的所有剩余项目并重新计算总数，然后更新JLabel。

阅读How to Write a ListDataListener上Swing教程中的部分，以获取有关工作示例和更多信息。

尝试更新总订单列表

1 个答案: