我如何添加用户将在GUI中指定项目的数量

Question

基本上，我想创建一个GUI，允许用户从给定列表中选择一个项目，然后显示添加项目的总额，即价格。所以，它将是项目的数量*价格。数量将由用户输入。到目前为止，这就是代码，我想修改代码，让用户输入数量，并在GUI中进行整体计算和显示。

我如何添加用户将在GUI中指定项目的数量？

类别Item

public class Item {
private String itemName;
private Integer itemPrice;
public Item(){}
public Item(String itemName, int itemPrice){
    this.itemName = itemName;
    this.itemPrice = itemPrice;
}
public String getItemName() {
    return itemName;
}
public void setItemName(String itemName) {
    this.itemName = itemName;
}
public Integer getItemPrice() {
    return itemPrice;
}
public void setItemPrice(Integer itemPrice) {
    this.itemPrice = itemPrice;
}
@Override
public String toString(){
    return this.itemName;
}
}

类别ShoppingCart

import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;
import javax.swing.*;
public class ShoppingCart extends JFrame {
    private JList leftlist;
    private JList rightlist;
    private JButton addbutton;
    private JButton totalbutton;
    private JLabel totalLabel;

public ShoppingCart() {
    super("Shopping Cart");
    setLayout(new FlowLayout());
    // preparing item list it might be coming from somewhere else
    List<Item> itemList = new ArrayList<Item>();
    itemList.add(new Item("Apple", 10));
    itemList.add(new Item("Carrot", 40));
    itemList.add(new Item("Cucumber", 50));
    itemList.add(new Item("Iphone 6", 6000));
    itemList.add(new Item("Galaxy S6", 1100));
    itemList.add(new Item("BlackBerry", 1300));
    itemList.add(new Item("HairDryer", 200));
    itemList.add(new Item("Ironer", 300));
    itemList.add(new Item("Vacuum Cleaner", 400));
    leftlist = new JList(itemList.toArray());
    leftlist.setVisibleRowCount(5);
    leftlist
            .setSelectionMode(ListSelectionModel.MULTIPLE_INTERVAL_SELECTION);
    add(new JScrollPane(leftlist));
    addbutton = new JButton("ADD");
    addbutton.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent event) {
            //make sure you preserve the previously selected list items
            int size = rightlist.getModel().getSize();
            Set objects = new LinkedHashSet();
            for (int i = 0; i < size; i++) {
                objects.add(rightlist.getModel().getElementAt(i));
            }
            objects.addAll(Arrays.asList(leftlist.getSelectedValues()));
            rightlist.setListData(objects.toArray());
        }
    });
    add(addbutton);
    rightlist = new JList();
    rightlist.setVisibleRowCount(5);
    rightlist.setFixedCellWidth(55);
    rightlist.setFixedCellHeight(20);
    add(new JScrollPane(rightlist));
    totalbutton = new JButton("Total");
    totalbutton.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent event) {
            // iterate over item objects and calculate the total
            int size = rightlist.getModel().getSize();
            Integer totalAmount = 0;
            for (int i = 0; i < size; i++) {
                Object obj = leftlist.getModel().getElementAt(i);
                Item item = (Item) obj;
                totalAmount += item.getItemPrice();
            }
            //update the total Amount label
            totalLabel.setText("Total Amount : " + totalAmount);
        }
    });
    add(totalbutton);
    totalLabel = new JLabel("Total Amount : ");
    add(totalLabel);
}
public static void main(String[] args) {
    ShoppingCart list = new ShoppingCart();
    list.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    list.setSize(300, 300);
    list.setVisible(true);
}
}

Answer 1

这基本上是一个库存场景。。首先你应该提示用户从列表中选择一个项目，然后在焦点向外的价格字段应该根据产品名称自动获得文本。。用户将输入数量。。然后使用以下代码计算总价。。。

 private void total_buttonActionPerformed(java.awt.event.ActionEvent evt) {                                             

        float price=Float.parseFloat(price_txt.getText());
        float quantity=Float.parseFloat(quantity_txt.getText());
        float sum=price*quantity;
        total_txt.setText(""+sum);
}             

//注意，对于库存，您还应该检查产品的可用性。。

private void quantity_txtFocusLost(java.awt.event.FocusEvent evt) {                                       
    int quantity=Integer.parseInt(quantity_txt.getText());
    int available=Integer.parseInt(availability_txt.getText());
    if(quantity>available)
    {
        JOptionPane.showMessageDialog(rootPane, "Entered quantity is unavailable.");
        quantity_txt.requestFocus();
    }

}