java我应该在哪里声明一个类中的变量以在另一个类中使用？
我有两个类，Window和CustomerInfo。Window类显示一个登录用户界面，用户将在其中的文本字段中输入有效的用户名和密码。我已经编写了正确接受正确用户名和密码并拒绝错误信息的代码。如果信息正确，CustomerInfo类将打开多个文本字段，其中包含用户信息，如姓名、地址、电话号码等。此用户信息存储在SQLite数据库中，当用户登录时，我将从该数据库中提取这些信息，并使用以前输入和保存的相应信息设置这些文本字段
如您所见，我正在使用SELECTFROM语句访问此信息。我需要包括一个WHERE子句，该子句将从输入的用户名中提取（例如，从CustInfo中选择FirstName，其中username=username）。用户名变量将是登录的用户。我试图通过字符串username=textFieldUsernameCust设置该变量。getText（）；我不知道在哪里声明这个变量语句，因为textFieldUsernameCust文本框在Window类中，我需要在CustomerInfo类中使用这个变量
窗口类
public class Window {
private JFrame frame;
public static JTextField textFieldUsernameCust;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
Window window = new Window();
window.frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
Connection connection=null;
public JPasswordField passwordFieldCust;
public JTextField textFieldUsernameComp;
public JPasswordField passwordFieldComp;
/**
* Create the application.
*/
public Window() {
initialize();
connection=sqliteConnection.dbConnector();
}
/**
* Initialize the contents of the frame.
*/
private void initialize() {
frame = new JFrame();
frame.setResizable(false);
frame.setBounds(100, 100, 619, 377);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().setLayout(null);
JLabel lblUsername = new JLabel("Username:");
lblUsername.setFont(new Font("Tahoma", Font.PLAIN, 14));
lblUsername.setBounds(86, 166, 86, 14);
frame.getContentPane().add(lblUsername);
JLabel lblPassword = new JLabel("Password:");
lblPassword.setFont(new Font("Tahoma", Font.PLAIN, 14));
lblPassword.setBounds(86, 202, 65, 14);
frame.getContentPane().add(lblPassword);
textFieldUsernameCust = new JTextField();
textFieldUsernameCust.setBounds(182, 165, 97, 20);
frame.getContentPane().add(textFieldUsernameCust);
textFieldUsernameCust.setColumns(10);
JButton btnLoginCust = new JButton("Login (Customer)");
btnLoginCust.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
try {
String query="select * from CustomerInfo where Username=? and Password=?";
PreparedStatement pst=connection.prepareStatement(query);
pst.setString(1, textFieldUsernameCust.getText() );
pst.setString(2, passwordFieldCust.getText() );
ResultSet rs=pst.executeQuery();
int count=0;
while(rs.next()){
count=count+1;
}
if (count==1)
{
JOptionPane.showMessageDialog(null, "Login Successful");
frame.dispose();
CustomerInfo custinfo=new CustomerInfo();
custinfo.setVisible(true);
}
else if(count>1)
{
JOptionPane.showMessageDialog(null, "Duplicate Username or Password");
}
else
{
JOptionPane.showMessageDialog(null, "Username or Password is incorrect. Please try again");
}
rs.close();
pst.close();
} catch(Exception e)
{
JOptionPane.showMessageDialog(null, e);
}
}
});
btnLoginCust.setBounds(116, 259, 117, 23);
frame.getContentPane().add(btnLoginCust);
JLabel lblWelcome = new JLabel("Welcome to InsurU");
lblWelcome.setFont(new Font("Tahoma", Font.BOLD | Font.ITALIC, 20));
lblWelcome.setBounds(221, 46, 232, 20);
frame.getContentPane().add(lblWelcome);
passwordFieldCust = new JPasswordField();
passwordFieldCust.setBounds(182, 201, 97, 20);
frame.getContentPane().add(passwordFieldCust);
JLabel label = new JLabel("Username:");
label.setFont(new Font("Tahoma", Font.PLAIN, 14));
label.setBounds(329, 168, 86, 14);
frame.getContentPane().add(label);
JLabel label_1 = new JLabel("Password:");
label_1.setFont(new Font("Tahoma", Font.PLAIN, 14));
label_1.setBounds(329, 204, 65, 14);
frame.getContentPane().add(label_1);
textFieldUsernameComp = new JTextField();
textFieldUsernameComp.setColumns(10);
textFieldUsernameComp.setBounds(425, 165, 97, 20);
frame.getContentPane().add(textFieldUsernameComp);
JButton btnLogincompanyt = new JButton("Login (Company)");
btnLogincompanyt.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
try {
String query="select * from CustomerInfo where UserName=? and Password=?";
PreparedStatement pst=connection.prepareStatement(query);
pst.setString(1, textFieldUsernameComp.getText() );
pst.setString(2, passwordFieldComp.getText() );
ResultSet rs=pst.executeQuery();
int count=0;
while(rs.next()){
count=count+1;
}
if (count==1)
{
JOptionPane.showMessageDialog(null, "Login Successful");
frame.dispose();
CompanyInfo compinfo=new CompanyInfo();
compinfo.setVisible(true);
}
else if(count>1)
{
JOptionPane.showMessageDialog(null, "Duplicate Username or Password");
}
else
{
JOptionPane.showMessageDialog(null, "Username or Password is incorrect. Please try again");
}
rs.close();
pst.close();
} catch(Exception e)
{
JOptionPane.showMessageDialog(null, e);
}
}
});
btnLogincompanyt.setBounds(374, 259, 117, 23);
frame.getContentPane().add(btnLogincompanyt);
JLabel lblCustomerLogin = new JLabel("Customer Login");
lblCustomerLogin.setFont(new Font("Tahoma", Font.PLAIN, 16));
lblCustomerLogin.setBounds(116, 107, 117, 22);
frame.getContentPane().add(lblCustomerLogin);
JLabel lblCompanyLogin = new JLabel("Company Login");
lblCompanyLogin.setFont(new Font("Tahoma", Font.PLAIN, 16));
lblCompanyLogin.setBounds(374, 108, 117, 20);
frame.getContentPane().add(lblCompanyLogin);
passwordFieldComp = new JPasswordField();
passwordFieldComp.setBounds(425, 201, 97, 20);
frame.getContentPane().add(passwordFieldComp);
}
}
CustomerInfo类
public class CustomerInfo extends JFrame {
private JPanel contentPane;
private JTextField textFieldFirstName;
private JTextField textFieldLastName;
private JTextField textFieldAdress;
private JTextField textFieldCity;
private JTextField textFieldZipCode;
private JTextField textFieldEmail;
private JTextField textFieldNumber;
private JTextField textFieldAge;
private JTextField textFieldUsername;
private JTextField textFieldPassword;
private JTextField textField_10;
private JTextField textField_11;
private JTextField textField_12;
private JTextField textField_13;
private JTextField textField_14;
private JTextField textField_15;
private JTextField textField_16;
private JTextField textField_17;
private JTextField textFieldAnnualCar1;
private JTextField textField_19;
private JTextField textField_20;
private JTextField textFieldAnnualCar2;
private JTextField textField_22;
private JTextField textField_23;
private JTextField textFieldAnnualCar3;
private JTextField textFieldTotalDrivers;
private JTextField textField_26;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
CustomerInfo frame = new CustomerInfo();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the frame.
*/
public CustomerInfo() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 623, 382);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
contentPane.setLayout(null);
JTabbedPane tabbedPane = new JTabbedPane(JTabbedPane.TOP);
tabbedPane.setBounds(10, 11, 593, 327);
contentPane.add(tabbedPane);
JPanel panel = new JPanel();
tabbedPane.addTab("Profile", null, panel, null);
panel.setLayout(null);
JLabel lblFirstName = new JLabel("First Name:");
lblFirstName.setBounds(26, 26, 65, 14);
panel.add(lblFirstName);
textFieldFirstName = new JTextField();
textFieldFirstName.setBounds(92, 23, 86, 20);
panel.add(textFieldFirstName);
textFieldFirstName.setColumns(10);
JLabel lblAdress = new JLabel("Adress:");
lblAdress.setBounds(26, 51, 46, 14);
panel.add(lblAdress);
JLabel lblDOB = new JLabel("Date of Birth:");
lblDOB.setBounds(26, 155, 76, 14);
panel.add(lblDOB);
JLabel lblRelationship = new JLabel("Relationship Status:");
lblRelationship.setBounds(310, 186, 96, 14);
panel.add(lblRelationship);
JLabel lblEmail = new JLabel("E-mail:");
lblEmail.setBounds(26, 211, 46, 14);
panel.add(lblEmail);
JLabel lblPhone = new JLabel("Phone Number:");
lblPhone.setBounds(310, 211, 76, 14);
panel.add(lblPhone);
JLabel lblLastName = new JLabel("Last Name:");
lblLastName.setBounds(204, 26, 65, 14);
panel.add(lblLastName);
textFieldLastName = new JTextField();
textFieldLastName.setBounds(270, 23, 86, 20);
panel.add(textFieldLastName);
textFieldLastName.setColumns(10);
JLabel lblCityAdress = new JLabel("City:");
lblCityAdress.setBounds(26, 76, 46, 14);
panel.add(lblCityAdress);
JLabel lblStateAdress = new JLabel("State:");
lblStateAdress.setBounds(26, 101, 46, 14);
panel.add(lblStateAdress);
JLabel lblZipCode = new JLabel("Zip Code:");
lblZipCode.setBounds(26, 126, 46, 14);
panel.add(lblZipCode);
textFieldAdress = new JTextField();
textFieldAdress.setBounds(92, 48, 264, 20);
panel.add(textFieldAdress);
textFieldAdress.setColumns(10);
textFieldCity = new JTextField();
textFieldCity.setBounds(92, 73, 86, 20);
panel.add(textFieldCity);
textFieldCity.setColumns(10);
textFieldZipCode = new JTextField();
textFieldZipCode.setBounds(92, 123, 86, 20);
panel.add(textFieldZipCode);
textFieldZipCode.setColumns(10);
JComboBox comboBoxState = new JComboBox();
comboBoxState.setModel(new DefaultComboBoxModel(new String[] {"Al", "AK", "AZ", "AR", "CA", "CO", "CT", "DE", "FL", "GA", "HI", "ID", "IL", "IN", "IA", "KS", "KY", "LA", "ME", "MD", "MA", "MI", "MN", "MS", "MO", "MT", "NE", "NV", "NH", "NJ", "NM", "NY", "NC", "ND", "OH", "OK", "OR", "PA", "RI", "SC", "SD", "TN", "TX", "UT", "VT", "VA", "WA", "WV", "WI", "WY"}));
comboBoxState.setBounds(92, 98, 46, 20);
panel.add(comboBoxState);
JComboBox comboBoxDBMonth = new JComboBox();
comboBoxDBMonth.setModel(new DefaultComboBoxModel(new String[] {"01", "02", "03", "04", "05", "06", "07", "08", "09", "10", "11", "12"}));
comboBoxDBMonth.setBounds(92, 152, 46, 20);
panel.add(comboBoxDBMonth);
JComboBox comboBoxDBDay = new JComboBox();
comboBoxDBDay.setModel(new DefaultComboBoxModel(new String[] {"1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", "14", "15", "16", "17", "18", "19", "20", "21", "22", "23", "24", "25", "26", "27", "28", "29", "30", "31"}));
comboBoxDBDay.setBounds(141, 152, 37, 20);
panel.add(comboBoxDBDay);
JComboBox comboBoxDBYear = new JComboBox();
comboBoxDBYear.setBounds(182, 152, 65, 20);
panel.add(comboBoxDBYear);
textFieldEmail = new JTextField();
textFieldEmail.setBounds(92, 208, 130, 20);
panel.add(textFieldEmail);
textFieldEmail.setColumns(10);
JComboBox comboRelationshipStatus = new JComboBox();
comboRelationshipStatus.setModel(new DefaultComboBoxModel(new String[] {"Married", "Single", "Divorced", "Widowed", "Domestic Partners"}));
comboRelationshipStatus.setBounds(422, 183, 86, 20);
panel.add(comboRelationshipStatus);
textFieldNumber = new JTextField();
textFieldNumber.setBounds(422, 208, 122, 20);
panel.add(textFieldNumber);
textFieldNumber.setColumns(10);
Statement stmt = null;
Connection connection=null;
connection=sqliteConnection.dbConnector();
try{
Class.forName("org.sqlite.JDBC");
Connection conn=DriverManager.getConnection("jdbc:sqlite:C:\\Users\\Gregory\\workspacefinal\\Customer.sqlite");
stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery("SELECT FirstName, LastName, Adress, City, ZipCode, Email, PhoneNumber, Age FROM CustomerInfo WHERE Username = username");
String firstName = rs.getString("FirstName");
String lastName = rs.getString("LastName");
String adress = rs.getString("Adress");
String city = rs.getString("City");
String zipcode = rs.getString("ZipCode");
String email = rs.getString("Email");
String phonenumber = rs.getString("PhoneNumber");
String age = rs.getString("Age");
textFieldFirstName.setText(firstName);
textFieldLastName.setText(lastName);
textFieldAdress.setText(adress);
textFieldCity.setText(city);
textFieldZipCode.setText(zipcode);
textFieldEmail.setText(email);
textFieldNumber.setText(phonenumber);
textFieldAge.setText(age);
stmt.close();
conn.close();
}
catch(Exception e){
JOptionPane.showMessageDialog(null, e);
}
# 1 楼答案
gui逻辑和应用程序逻辑的这种混合非常糟糕
您的主要职能应按以下结构进行：
LoginInfo类中返回它们，该类专门创建用于保存用户名和密码CustomerInfo类中返回该信息。（不要调用对话框CustomerInfo。该对话框应称为CustomerInfoDialog。）gui函数返回null而不是实际的
LoginInfo或CustomerInfo对象意味着用户已取消# 2 楼答案
首先，CustomerInfo看起来做的比名字暗示的要多。它扩展了JFrame，这意味着它是视图的一部分。您应该在类名中反映这一点
考虑将用户名传递给CuuthEnror的构造函数。