Question

我正在尝试建立一个网上商店（我的任务）。我，在添加框架时遇到问题。是否有一些不同的方法在textpad中添加框架或我，我做错了。有人可以告诉我一种方法来做到这一点。

谢谢！

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import java.awt.Color;
import javax.swing.ImageIcon;
import javax.swing.*;

public class AppStore extends JFrame
{

    private static final int FRAME_WIDTH = 1050;
    private static final int FRAME_HEIGHT = 550;

    private static final int CANDY_GAME_STOCK = 8;

    private static final int DEFAULT_QUANTITY = 0;
    private static final double DEFAULT_PRICE = 3.5;

    private JLabel candyCrush;
    private JLabel candyStockLabel;
    private JLabel priceLabel;
    private JLabel candyImage;
    private JLabel error;
    private JLabel candyCartLabel;
    private ImageIcon candy;
    private JLabel adding;
    private JButton incCandy;
    private JButton decCandy;
    private JButton buy;
    private JButton addTo;
    private JButton proceed;
    private JTextField quantity;
    private JTextField candyStockField;
    private static JPanel cartPanel;


    private double price;
    private int candyStock;
    private int candyGame;
    private double sum;

    public AppStore()
    {

        price = DEFAULT_PRICE;

        candyStock = CANDY_GAME_STOCK;

        priceLabel = new JLabel("Price: ");
        candyCrush = new JLabel("Candy-Crush Game: ");
        candyStockLabel = new JLabel("In stock: ");
        candyCartLabel = new JLabel("Dear Customer! ");
        error = new JLabel(" ");
        adding = new JLabel("Add this item to shopping cart");

        ImageIcon candy = new ImageIcon("candycrush.jpg");
        candyImage = new JLabel(new ImageIcon("candycrush.jpg"));
        candyImage = new JLabel(candy);

        createTextField();
        createButton();
        createPanel();
        setSize(FRAME_WIDTH, FRAME_HEIGHT);


    }

    private void createTextField()
    {

        final int FIELD_WIDTH = 4;
        final int STOCK_WIDTH = 2;
        quantity = new JTextField(FIELD_WIDTH);
        quantity.setText("" + DEFAULT_QUANTITY);
        candyStockField = new JTextField(STOCK_WIDTH);
        candyStockField.setText("" + CANDY_GAME_STOCK);
    }

    class IncrementCandy implements ActionListener
    {
        public void actionPerformed(ActionEvent event)
        {
            int addition = 1;
            candyGame = candyGame + addition;
            quantity.setText("" + candyGame);

            int newQuantity = Integer.parseInt(quantity.getText());
            double newPrice  = price * newQuantity;
            priceLabel.setText("Price: " + newPrice);
        }
    }

    class DecrementCandy implements ActionListener
    {
        public void actionPerformed(ActionEvent event)
        {
            int subtraction = 1;
            candyGame = candyGame - subtraction;
            quantity.setText("" + candyGame);

            int newQuantity = Integer.parseInt(quantity.getText());
            double newPrice  = price * newQuantity;
            priceLabel.setText("Price: " + newPrice);
        }
    }

    class AddToCartListener implements ActionListener
    {
        public void actionPerformed(ActionEvent event)
        {
            int newQuantity = Integer.parseInt(quantity.getText());
            if((newQuantity > 0)&&(newQuantity <= CANDY_GAME_STOCK))
            {
                int remainingStock = CANDY_GAME_STOCK - newQuantity;
                candyStockField.setText("" + remainingStock);
                error.setVisible(false);


            }

            if((newQuantity > CANDY_GAME_STOCK)||(newQuantity <= 0))
            {
                error.setText("Invalid, Selection");
                error.setVisible(true);
            }

        }

    }

    class CartDisplay implements ActionListener
    {
        public void actionPerformed(ActionEvent event)
        {
            JFrame shoppingCart = new JFrame();

            int newQuantity = Integer.parseInt(quantity.getText());
            candyCartLabel.setText("Dear Customer! you added " + newQuantity);
            cartPanel.add(candyCartLabel);
            add(cartPanel);
            shoppingCart.setVisible(true);
        }
    }



    private void createButton()
    {
        buy =  new JButton("Buy");


        incCandy = new JButton("+");
        ActionListener listener = new IncrementCandy();
        incCandy.addActionListener(listener);

        decCandy = new JButton("-");
        ActionListener listener2 = new DecrementCandy();
        decCandy.addActionListener(listener2);

        addTo = new JButton("Add to Cart");
        ActionListener stockReduction = new AddToCartListener();
        addTo.addActionListener(stockReduction);

        proceed = new JButton("Proceed");
        ActionListener display = new CartDisplay();
        proceed.addActionListener(display);





    }

    private void createPanel()
    {

        JPanel panel = new JPanel();
        panel.setBackground(Color.GRAY);
        panel.add(candyImage);
        panel.add(candyCrush);
        panel.add(quantity);
        panel.add(candyStockLabel);
        panel.add(candyStockField);
        panel.add(incCandy);
        panel.add(decCandy);
        panel.add(priceLabel);
        panel.add(addTo);
        panel.add(proceed);
        panel.add(error);
        panel.add(adding);
        adding.setOpaque(true);
        adding.setBackground(Color.WHITE);
        add(panel);


    }



    public static void main(String [] args)
    {
        AppStore frame = new AppStore();
        frame.setTitle("Appstore");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);

    }



}

Answer 1

我认为您在使用它之前错过了初始化cartPanel，在AppStore构造函数中初始化它。在为内框使用setVisible（true）之前，你应该为它设置Size。另请参阅JInternalFrame（https://docs.oracle.com/javase/7/docs/api/javax/swing/JInternalFrame.html）

如何使JFrame按钮在Textpad

1 个答案: