如何在Java Swing中将数据从数组从一种形式传递到另一种形式？

Question

I have two windows. The first is a Login window and the second is the Main Menu window. I also have a class called Car. What I'm trying to do is to pass a value from an array in the Login window to the Main Window. So that when the user clicks the BuyCar button the price would show. I'm fairly new to Java Swing, so any help would be appreciated.

I'm getting a "The constructor in Main Window() is undefined" in this bit of code in the Main Window, but when I try to fix it , I'm getting an error.

    public static void main(String[] args) {
     //Schedule a job for the event-dispatching thread: creating and showing this application's GUI.
    SwingUtilities.invokeLater(new Runnable() {
        public void run() {
        new MainWindow(); //problem here
        }

What am I doing wrong? Thanks!

CAR

public class Car {
        String make;
        String model;
        float price;
        String color;
        int year;
        int payterms;
        int purchasetype; //1 – Buy, 2-Finance, 3-Lease
        int months; //months
        float payamount; // monthly payment amount

Car ()
    {
        make = "";
        model = "";
        price = 0.00f;
        color = "";
        year = 0;
        purchasetype = 0; //1 – Buy, 2-Finance, 3-Lease
        months= 0; //months
        payamount = 0f; // monthly payment amount
    }

Car (String m, String m2, float p, String c, int y, int pt, int m3, float pa)
    {   make = m;
        model = m2;
        price = p;
        color = c;
        year = y;
        purchasetype = pt;
        payterms = m3;
        payamount = pa;
    }

float buyCar(int pt, int terms)
    {
        purchasetype = pt;
        months = terms;
        if (pt == 2 || pt == 3)
        {   payamount = price/months;   }
        return payamount;
    }
}

LOGIN WINDOW

package pkgLogin;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class LoginWindow extends JFrame {
Car c;

LoginWindow() {

    c = new Car("Cadillac", "ATS", 120000.00f, "red", 2012, 0, 0, 0.00f);

    //Create a new frame container
    setTitle("Login Form");

    //Give the frame an initial size and center the window
    setSize(400, 220);
    setLocationRelativeTo(null);

    //Terminate the program when the user closes the application
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    //Make two buttons
    JButton okButton = new JButton ("OK"); 
    okButton.setFont(new Font("Helvetica", Font.BOLD, 12));
    okButton.setOpaque(true);
    okButton.setPreferredSize(new Dimension(85, 22));
    okButton.setBackground(new Color(255, 250, 240));
    okButton.setForeground(new Color(255, 160, 122));

    JButton cancelButton = new JButton ("Cancel");  
    cancelButton.setFont(new Font("Helvetica", Font.BOLD, 12));
    cancelButton.setOpaque(true);
    cancelButton.setPreferredSize(new Dimension(85, 22));
    cancelButton.setBackground(new Color(255, 250, 240));
    cancelButton.setForeground(new Color(255, 160, 122));

    //Create text based label
    JLabel userLabel = new JLabel("Username:");
    userLabel.setFont(new Font("Helvetica", Font.BOLD, 12));
    userLabel.setForeground(new Color(255, 250, 240));
    JLabel passwordLabel = new JLabel("Password:");
    passwordLabel.setFont(new Font("Helvetica", Font.BOLD, 12));
    passwordLabel.setForeground(new Color(255, 250, 240));

    JLabel messageLabel = new JLabel("Click HERE if you've lost your card");
    messageLabel.setFont(new Font("Helvetica", Font.BOLD, 11));
    messageLabel.setForeground(new Color(255, 250, 240));

    //Create field label
    JTextField userField = new JTextField(10);
    userField.setBackground(new Color(255, 255, 255));
    JPasswordField passwordField = new JPasswordField(10);
    passwordField.setEchoChar('*');

    //Add listener to CANCEL button
    cancelButton.addActionListener (new ActionListener () {
        public void actionPerformed(ActionEvent e){
            //Execute when button is pressed
        JOptionPane.showMessageDialog(null, "Thank you. Goodbye!", "Inane warning",JOptionPane.WARNING_MESSAGE);
        System.exit(0);
    }});

    //Add listener to OK button
    okButton.addActionListener (new ActionListener () {

        public void actionPerformed(ActionEvent e){
            //Execute when button is pressed
            userField.requestFocusInWindow();
            String typeduser = userField.getText();
            String enteredpass = new String (passwordField.getPassword());

            //Check password length
            if (enteredpass.length() != 8 )
            {
                JOptionPane.showMessageDialog(null, "Your password is either too long, or too short! "
                        + "\nPassword should be 8 characters long!", "Inane warning",JOptionPane.WARNING_MESSAGE);
                System.exit(0);
            }

            //Check to see that user has filled in all information
            if (enteredpass.equals("") || typeduser.equals(""))
            {   JOptionPane.showMessageDialog(null, "Information is missing! Try Again!", 
                    "Inane warning",JOptionPane.WARNING_MESSAGE);
                System.exit(0);
            }

            //Validate
            if (typeduser.equals("jenaya") && enteredpass.equals("hellojen"))
            {   JOptionPane.showMessageDialog(null, "Welcome!", 
                    "Welcome",JOptionPane.INFORMATION_MESSAGE);
            SwingUtilities.invokeLater(new Runnable() {
                public void run() {
                    setVisible(false);
                        new MainWindow(c);
                }
            });
            }
            else
            {
                JOptionPane.showMessageDialog(null, "Incorrect Login!", "Inane warning",JOptionPane.WARNING_MESSAGE);
            }
    }});

    //Add the panel to the content page
    JPanel panel = new JPanel();
    add(panel);

    panel.setBackground(new Color(255, 160, 122));
    //Display the frame
    setVisible(true);

    //Set the layout
    SpringLayout layout = new SpringLayout();
    panel.setLayout(layout);

    //Add the label to the content pane
    panel.add(userLabel);
    panel.add(userField);

    //Add the text field to the content pane
    panel.add(passwordLabel);
    panel.add(passwordField);

    panel.add(messageLabel);

    //Add buttons to the content
    panel.add(okButton);
    panel.add(cancelButton);

    //Adjust constraints for the label.
    layout.putConstraint(SpringLayout.WEST, userLabel, 85, SpringLayout.WEST, panel);  //right
    layout.putConstraint(SpringLayout.NORTH, userLabel, 25, SpringLayout.NORTH, panel);  //top
    layout.putConstraint(SpringLayout.WEST, passwordLabel, 85, SpringLayout.WEST, panel);
    layout.putConstraint(SpringLayout.NORTH, passwordLabel, 55, SpringLayout.NORTH, panel);

    //Adjust constraints for the text field so it's at (<label's right edge>).
    layout.putConstraint(SpringLayout.WEST, userField, 10,  SpringLayout.EAST, userLabel);
    layout.putConstraint(SpringLayout.NORTH, userField, 25,  SpringLayout.NORTH, panel);
    layout.putConstraint(SpringLayout.WEST, passwordField, 10,  SpringLayout.EAST, passwordLabel);
    layout.putConstraint(SpringLayout.NORTH, passwordField, 55,  SpringLayout.NORTH, panel);

    //Adjust constraints for the buttons.
    layout.putConstraint(SpringLayout.WEST, okButton, 85, SpringLayout.WEST, panel);
    layout.putConstraint(SpringLayout.NORTH, okButton, 90, SpringLayout.NORTH, panel);
    layout.putConstraint(SpringLayout.WEST, cancelButton, 195,  SpringLayout.WEST, panel);
    layout.putConstraint(SpringLayout.NORTH, cancelButton, 90, SpringLayout.NORTH, panel);
    //Adjust constraints for the labels.
    layout.putConstraint(SpringLayout.WEST, messageLabel, 91,  SpringLayout.WEST, panel);
    layout.putConstraint(SpringLayout.NORTH, messageLabel, 145, SpringLayout.NORTH, panel);
}

public static void main(String[] args) {
    new LoginWindow();
    }
}

MAIN MENU WINDOW

public class MainWindow extends JFrame{
MainWindow(Car c) {
    //Create a new frame container
    setTitle("Main Window Form");

    //Give the frame an initial size and center the window
    setSize(400, 400);
    setLocationRelativeTo(null);

    //Terminate the program when the user closes the application
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    ImageIcon image = new ImageIcon("G:/JSProject/images.jpg");
    JLabel imagelabel = new JLabel(image);
    imagelabel.setPreferredSize(new Dimension(264, 191));

    JLabel messageLabel = new JLabel("This car is worth $200,000.00");
    messageLabel.setFont(new Font("Helvetica", Font.BOLD, 11));
    messageLabel.setForeground(new Color(255, 250, 240));

    JButton okButton = new JButton ("OK"); 
    okButton.setFont(new Font("Helvetica", Font.BOLD, 12));
    okButton.setOpaque(true);
    okButton.setPreferredSize(new Dimension(85, 22));
    okButton.setBackground(new Color(255, 250, 240));
    okButton.setForeground(new Color(255, 160, 122));

    JButton cancelButton = new JButton ("Cancel");  
    cancelButton.setFont(new Font("Helvetica", Font.BOLD, 12));
    cancelButton.setOpaque(true);
    cancelButton.setPreferredSize(new Dimension(85, 22));
    cancelButton.setBackground(new Color(255, 250, 240));
    cancelButton.setForeground(new Color(255, 160, 122));

     JRadioButton buyButton = new JRadioButton("Buy");
     buyButton.setMnemonic(KeyEvent.VK_B);
     buyButton.setActionCommand("Buy");
     buyButton.setSelected(true);

     JRadioButton leaseButton = new JRadioButton("Lease");
     leaseButton.setMnemonic(KeyEvent.VK_B);
     leaseButton.setActionCommand("Lease");

     JRadioButton financeButton = new JRadioButton("Finance");
     financeButton.setMnemonic(KeyEvent.VK_B);
     financeButton.setActionCommand("Finance");

     ButtonGroup bG = new ButtonGroup();
     bG.add(buyButton);
     bG.add(leaseButton);
     bG.add(financeButton);
     buyButton.setSize(100,200);
     leaseButton.setSize(100,200);
     financeButton.setSize(100,200);

    //Add listener
    cancelButton.addActionListener (new ActionListener () {
        public void actionPerformed(ActionEvent e){
            //Execute when button is pressed
        JOptionPane.showMessageDialog(null, "Thank you. Goodbye!", "Program Exit",JOptionPane.INFORMATION_MESSAGE);
        System.exit(0);
    }});

    //Add listener to OK button
            okButton.addActionListener (new ActionListener () {

                public void actionPerformed(ActionEvent e){
                    //Execute when button is selected
                    if (buyButton.isSelected())
                    {
                        //setVisible(false);
                        JOptionPane.showMessageDialog(null, "The price of the car is "+c.price, "Program Exit",JOptionPane.INFORMATION_MESSAGE);
                        //new BuyCarWindow(c).setVisible(true);
                    }

                    else if (leaseButton.isSelected())
                    {
                        setVisible(false);
                        //LeaseWindow.setVisible(true);
                    }

                    else if (financeButton.isSelected())
                    {
                        setVisible(false);
                        //FinanceWindow.setVisible(true);
                    }
            }});


    //Create text based label
    JLabel userLabel = new JLabel("Main Window");
    userLabel.setFont(new Font("Helvetica", Font.BOLD, 12));
    userLabel.setForeground(new Color(255, 250, 240));

    //Add the panel to the content page
    JPanel panel = new JPanel();
    add(panel);
    panel.setBackground(new Color(255, 160, 122));

    //Display the frame
    setVisible(true);

    //Set the layout
    SpringLayout layout = new SpringLayout();
    panel.setLayout(layout);

    //Add the label to the content pane 
    panel.add(userLabel);

    //Add buttons to the content
    panel.add(imagelabel);
    panel.add(messageLabel);
    panel.add(okButton);
    panel.add(cancelButton);
    panel.add(buyButton);
    panel.add(leaseButton);
    panel.add(financeButton);
    //this.pack();

    //Adjust constraints for the label.
    layout.putConstraint(SpringLayout.WEST, userLabel, 85, SpringLayout.WEST, panel);  //right
    layout.putConstraint(SpringLayout.NORTH, userLabel, 25, SpringLayout.NORTH, panel);  //top

    layout.putConstraint(SpringLayout.WEST, okButton, 85, SpringLayout.WEST, panel);
    layout.putConstraint(SpringLayout.NORTH, okButton, 90, SpringLayout.NORTH, panel);
    layout.putConstraint(SpringLayout.WEST, cancelButton, 180,  SpringLayout.WEST, panel);
    layout.putConstraint(SpringLayout.NORTH, cancelButton, 90, SpringLayout.NORTH, panel);

    layout.putConstraint(SpringLayout.WEST, buyButton, 100,  SpringLayout.WEST, panel);
    layout.putConstraint(SpringLayout.NORTH, buyButton, 50, SpringLayout.NORTH, panel);

    layout.putConstraint(SpringLayout.WEST, leaseButton, 150,  SpringLayout.WEST, panel);
    layout.putConstraint(SpringLayout.NORTH, leaseButton, 50, SpringLayout.NORTH, panel);

    layout.putConstraint(SpringLayout.WEST, financeButton, 220,  SpringLayout.WEST, panel);
    layout.putConstraint(SpringLayout.NORTH, financeButton, 50, SpringLayout.NORTH, panel);

  //Adjust constraints for the labels.
    layout.putConstraint(SpringLayout.WEST, messageLabel, 91,  SpringLayout.WEST, panel);
    layout.putConstraint(SpringLayout.NORTH, messageLabel, 145, SpringLayout.NORTH, panel);

    layout.putConstraint(SpringLayout.WEST, imagelabel, 91,  SpringLayout.WEST, panel);
    layout.putConstraint(SpringLayout.NORTH, imagelabel, 145, SpringLayout.NORTH, panel);
}

public static void main(String[] args) {
     //Schedule a job for the event-dispatching thread: creating and showing this application's GUI.
    SwingUtilities.invokeLater(new Runnable() {
        public void run() {
        new MainWindow();
        }

    });
}

}

Answer 1

Your MainWindow constructor requires a Car object to be passed to it as an argument.

new MainWindow(c);

However, this isn't sufficient unless you also define the variable c.

Car c = new Car();
new MainWindow(c);