Linking to another application when using preparestatement

Question

so I am using eclipse and mysql to create a login interface. The interface worked fine as a shell, so without being connected to the databse, and now I finally got it connected to the database but I'm running into the problem of linking it to another application upon successful login.

So for the shell of it I just gave the code a single username/password combo to proceed to the next part of the interface, but if I want to have the link work upon successful login in general, where do I place it in the code?

My code:

package project_files;



import javax.swing.JFrame;
import javax.swing.JToolBar;
import project_files.registration_test;
import project_files.root_login;
import project_files.gui_interface;
import project_files.video_interface;

import javax.swing.JList;
import javax.swing.JOptionPane;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.JTextPane;
import javax.swing.JPasswordField;
import javax.swing.JButton;
import javax.swing.JSeparator;
import java.awt.event.ActionListener;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;

public class login_sys {

    private JFrame frame;
    private JTextField txtUsername;
    private JPasswordField txtPassword;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    login_sys window = new login_sys();
                    window.frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the application.
     */
    public login_sys() {
        initialize();
    }


    /**
     * Initialize the contents of the frame.
     */
    private void initialize() {
        frame = new JFrame();
        frame.setBounds(200, 200, 523, 300);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().setLayout(null);

        JLabel LabelLogin = new JLabel("Login Page");
        LabelLogin.setBounds(209, 12, 100, 15);
        frame.getContentPane().add(LabelLogin);

        JLabel LabelUsername = new JLabel("Username");
        LabelUsername.setBounds(61, 68, 92, 17);
        frame.getContentPane().add(LabelUsername);

        JLabel LabelPassword = new JLabel("Password");
        LabelPassword.setBounds(61, 133, 66, 15);
        frame.getContentPane().add(LabelPassword);

        txtUsername = new JTextField();
        txtUsername.setBounds(244, 68, 124, 19);
        frame.getContentPane().add(txtUsername);
        txtUsername.setColumns(10);

        txtPassword = new JPasswordField();
        txtPassword.setBounds(244, 131, 124, 19);
        frame.getContentPane().add(txtPassword);

        JButton btnLogin = new JButton("Login");
        btnLogin.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {

                try {

                    Class.forName("com.mysql.cj.jdbc.Driver");
                    Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/userdatabase", "root", "pass1234");
                            Statement stmt= con.createStatement();
                            String sql = "Select * from user where Email = '" +txtUsername.getText()+"' and Password ='" +txtPassword.getText().toString()+"'";
                            ResultSet rs=stmt.executeQuery(sql);
                            if(rs.next())
                                JOptionPane.showMessageDialog(null, "Login Successfully...");
                            else 
                                JOptionPane.showMessageDialog(null, "Incorrect username and password...");
                            con.close();
                } catch(Exception e) {System.out.print (e);}




                String password = txtPassword.getText();
                String username = txtUsername.getText();

                if(password.contains("pass1234") && username.contains("root")){
                    txtPassword.setText(null);
                    txtUsername.setText(null);
                    root_login info = new root_login();
                    root_login.main(null);
                }
                else
                {

                    if(password.contains("pass1234") && username.contains("john@gmail.com")){
                        txtPassword.setText(null);
                        txtUsername.setText(null);
                        JOptionPane.showMessageDialog(null, "Login Successful", "Login Warning", JOptionPane.WARNING_MESSAGE);
                        video_interface info = new video_interface();
                        video_interface.main(null);
                    }
                    else
                    {

                            JOptionPane.showMessageDialog(null, "Invalid Login Details", "Login Error", JOptionPane.ERROR_MESSAGE);
                            txtPassword.setText(null);
                            txtUsername.setText(null);
                }

            }
            }});
        btnLogin.setBounds(23, 203, 130, 25);
        frame.getContentPane().add(btnLogin);

        JButton btnReset = new JButton("Reset");
        btnReset.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {

                txtUsername.setText(null);
                txtPassword.setText(null);
            }
        });
        btnReset.setBounds(212, 203, 114, 25);
        frame.getContentPane().add(btnReset); 

        JButton btnNewExit = new JButton("Exit");
        btnNewExit.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {

                JFrame frmLogin_sys = new JFrame("Exit");
                if (JOptionPane.showConfirmDialog(frmLogin_sys, "Confirm if you want to exit", "Login System",
                JOptionPane.YES_NO_OPTION)== JOptionPane.YES_NO_OPTION) {
                    System.exit(0);
                }
            }
        });
        btnNewExit.setBounds(373, 203, 114, 25);
        frame.getContentPane().add(btnNewExit);

        JSeparator separator = new JSeparator();
        separator.setBounds(12, 175, 499, 2);
        frame.getContentPane().add(separator);

        JSeparator separator_1 = new JSeparator();
        separator_1.setBounds(12, 36, 499, 2);
        frame.getContentPane().add(separator_1);

        JButton btnCreateAccount = new JButton("Create Account");
        btnCreateAccount.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0)


            {
        registration_test info = new registration_test();
        registration_test.main(null);
            }
        });
        btnCreateAccount.setBounds(135, 233, 265, 25);
        frame.getContentPane().add(btnCreateAccount);



    }
}

I was using (and it is still in my code currently)

if(password.contains("pass1234") && username.contains("john@gmail.com")){
                        txtPassword.setText(null);
                        txtUsername.setText(null);
                        JOptionPane.showMessageDialog(null, "Login Successful", "Login Warning", JOptionPane.WARNING_MESSAGE);
                        video_interface info = new video_interface();
                        video_interface.main(null);

to link a successful login to an additional application interface. Can i just use

video_interface info = new video_interface();
                            video_interface.main(null);

as I have been doing? Where is the correct place to add this code? The second application location is imported at the beginning of my code.

Answer 1

If you change the constructor of the video_interface class to initialize and show the GUI components (as you're currently doing in the login_sys.initialize method), you'll be just fine with

video_interface info = new video_interface()

There should only be one static void main(String[] args) method in any Java program.

As a side note, Java conventionally uses camelCasing, (eg JFrame , JTextField ) and if you adopt that convention your code will be easier to read.