Java-在简单的GUI Banking程序中运行总计

Question

I am having trouble trying to figure out how to code the deposits and withdrawals for my banking program and keep a running total. The program should start you with $0 in the bank and cannot go below $0. You are able to deposit and withdraw from this account and you can view who deposited and withdrew from the menu.

I need help trying to code the part that keeps the total of the account so that the user can't withdraw more than whats in the account. So if there is $100 in the account, they can't withdraw $200.

Note: The 'Create Account' action is just used to give yourself a unique ID when depositing/withdrawing and doesn't effect the login at all.

Login.java:

import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.util.Random;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JPasswordField;
import javax.swing.JTextField;

public class Login {

    private JFrame mainFrame;
    private JLabel headerLabel;
    private JLabel statusLabel;
    private JPanel controlPanel;

    int cid;

    public Login() {
        prepareGUI();
    }

    public static void main(String[] args) {
        Login login = new Login();
        login.showTextField();
    }

    private void prepareGUI() {
        mainFrame = new JFrame("Login");
        mainFrame.setSize(400, 400);
        mainFrame.setLayout(new GridLayout(3, 1));
        mainFrame.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent wE) {
                System.exit(0);
            }
        });
        headerLabel = new JLabel("", JLabel.CENTER);
        statusLabel = new JLabel("", JLabel.CENTER);

        statusLabel.setSize(350, 100);

        controlPanel = new JPanel();
        controlPanel.setLayout(new FlowLayout());

        mainFrame.add(headerLabel);
        mainFrame.add(controlPanel);
        mainFrame.add(statusLabel);
        mainFrame.setVisible(true);
    }

    private void showTextField() {
        headerLabel.setText("Account Access");

        JLabel namelabel = new JLabel("User ID: ", JLabel.RIGHT);
        JLabel passwordLabel = new JLabel("Password: ", JLabel.CENTER);
        final JTextField userText = new JTextField(6);
        final JPasswordField passwordText = new JPasswordField(6);

        JButton loginButton = new JButton("Login");
        JButton createAccountButton = new JButton("Create Account?");

        loginButton.addActionListener(new ActionListener() {
            @SuppressWarnings("deprecation")
            public void actionPerformed(ActionEvent e) {
                /*
                 * check for correct password/usernameinclude a desired
                 * 'hardcoded' username /password to verify againstuser input
                 * values for both username & password fieldsgive popup message
                 * if either username or password is incorrect
                 */
                if (userText.getText().equals("mister")
                        && passwordText.getText().equals("jim")) {

                    // close of Login window
                    mainFrame.dispose();
                    // open up MainWindow
                    new MainWindow(userText.getText(), cid);

                }

                else {
                    String message = "Incorrect username and/or password!\nTry again!";
                    JOptionPane.showMessageDialog(null, message);
                }
            }

        });

        createAccountButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {

                String name = JOptionPane.showInputDialog(null,
                        "Enter your name");
                // generate client id
                Random r = new Random();
                cid = r.nextInt(100000);
            }

        });

        controlPanel.add(namelabel);
        controlPanel.add(userText);
        controlPanel.add(passwordLabel);
        controlPanel.add(passwordText);
        controlPanel.add(loginButton);
        controlPanel.add(createAccountButton);
        mainFrame.setVisible(true);
    }
}

MainWindow.java:

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Vector;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JOptionPane;
import javax.swing.JScrollPane;
import javax.swing.JTable;

public class MainWindow extends JFrame {

    private JFrame mainFrame;
    private JLabel statusLabel;

    private JMenu file = new JMenu("File");
    private JMenu Account = new JMenu("Account");

    int cid;

    public MainWindow(String name, final int cid) {

        this.cid = cid;

        file.setMnemonic('F');
        JMenuItem ItemNew = new JMenuItem("New");
        ItemNew.setMnemonic('N');
        file.add(ItemNew);
        JMenuItem ItemExit = new JMenuItem("Exit");
        ItemExit.setMnemonic('x');
        file.add(ItemExit);

        ItemExit.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                System.exit(0);
            }
        });

        Account.setMnemonic('A');
        JMenuItem ItemDeposits = new JMenuItem("Deposits");
        ItemDeposits.setMnemonic('D');
        Account.add(ItemDeposits);

        JMenuItem ItemWithdraws = new JMenuItem("Withdrawals");
        ItemWithdraws.setMnemonic('W');
        Account.add(ItemWithdraws);

        JMenuItem ItemView = new JMenuItem("View Account");
        ItemView.setMnemonic('W');
        Account.add(ItemView);

        ItemDeposits.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {// add a deposit
                Double sBal = Double.parseDouble(JOptionPane.showInputDialog(
                        null, "Enter deposit amount"));
                // create Account object
                Account accountObj = new Account();
                accountObj.setBal(sBal);

                // show result
                System.out.println(accountObj.getCID() + accountObj.getBal());
                File f = new File("account.dat");
                try {
                    FileWriter fw = new FileWriter(f, true);
                    fw.write(cid + " " + accountObj.getBal() + "\n");

                    fw.close();
                } catch (IOException e1) {
                    // TODO Auto-generated catch block
                    e1.printStackTrace();
                }

            }
        });

        ItemWithdraws.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {// add a deposit
                Double sBal = Double.parseDouble(JOptionPane.showInputDialog(
                        null, "Enter withdrawal amount"));
                // create Account object
                Account accountObj = new Account();
                accountObj.setBal(sBal);

                // show result
                System.out.println(accountObj.getBal());
                File f = new File("account.dat");
                try {
                    FileWriter fw = new FileWriter(f, true);
                    fw.write(cid + " " + accountObj.getBal() + "\n");

                    fw.close();
                } catch (IOException e1) {
                    // TODO Auto-generated catch block
                    e1.printStackTrace();
                }

            }
        });

        ItemView.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                statusLabel.setVisible(false); // make status label invisible

                // set up JTable logic
                Vector<Vector<String>> myVector = new Vector<Vector<String>>(); // multidim
                                                                                // vector
                                                                                // (vector
                                                                                // of
                                                                                // vectors)

                try {

                    BufferedReader file = new BufferedReader(new FileReader(
                            "account.dat"));
                    String input;
                    while ((input = file.readLine()) != null) {
                        String[] temp = input.split(" "); // grab row (record)
                                                            // data parsed by a
                                                            // space
                        Vector<String> v = new Vector<String>(); // single dim
                                                                    // vector to
                                                                    // get
                                                                    // fields in
                                                                    // each
                                                                    // record
                        for (int i = 0; i < temp.length; i++) {
                            v.add(temp[i]); // add each field to vector
                        }
                        myVector.add(v); // add all field data as a new vector
                                            // row (represents a record of data
                                            // each dynamically!!!)
                    }
                    file.close();
                } catch (IOException e1) {
                    e1.printStackTrace(System.err);
                }

                Vector<String> columnData = new Vector<String>();
                columnData.addElement("ID");
                columnData.addElement("D/W");

                try {

                    JTable jt;

                    jt = new JTable(myVector, columnData);
                    jt.setBounds(30, 40, 200, 300);
                    JScrollPane sp = new JScrollPane(jt);

                    mainFrame.add(sp);

                } catch (Exception ex) {
                    System.out.println("There was a problem: " + ex);
                    ex.printStackTrace();
                }
            }
        });

        ItemNew.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {

            }
        });
        statusLabel = new JLabel();

        statusLabel.setText("Currently Logged In: " + name + " #" + cid);
        statusLabel.setHorizontalAlignment(JLabel.RIGHT);
        statusLabel.setVerticalAlignment(JLabel.TOP);

        prepareGUI();

    }

    private void prepareGUI() {
        mainFrame = new JFrame("Main");

        // adjust label position to sit in the upper right corner of window
        mainFrame.add(statusLabel);

        // add menu bar component to frame
        JMenuBar bar = new JMenuBar();
        bar.add(file); // set menu orders
        bar.add(Account);
        mainFrame.setJMenuBar(bar);

        mainFrame.setSize(400, 400);
        mainFrame.setVisible(true);

    }

}

Account.java:

public class Account {

    // data members
    double bal;
    static double intRate;
    int cid;
    String name;

    public Account() {
    }

    // getters
    double getBal() {
        return bal;
    }

    int getCID() {
        return cid;
    }

    // setters
    void setBal(double bal) {
        // update balance
        this.bal += bal;

    }

    void setCID(int cid) {
        this.cid = cid;
    }

    static void adjustIntRate(double r) {
        intRate = r;
    }

}

Answer 1

I need help trying to code the part that keeps the total of the account so that the user can't withdraw more than whats in the account. So if there is $100 in the account, they can't withdraw $200.

Although you make no effort to explain this, I suppose setBal is what you use to withdraw and deposit. I also assume that a negative value passed to this method means withdrawal.

If you want to completely block a withdraw request for more than what you have, use:

void setBal(double bal) {

    if (this.bal + bal >= 0)
        this.bal += bal;
}

Meaning, "if withdrawing the amount leaves you at 0 or more, proceed (otherwise ignore)".

If you want to allow to withdraw the maximum amount that sets you to 0, use:

void setBal(double bal) {

    if (this.bal + bal >= 0)
        this.bal += bal;
    else
        this.bal = 0;
}

Meaning, "if withdrawing the amount leaves you at 0 or more, otherwise you are left with 0".