I want to present the username from database JAVA Jframe

I have two JFrame windows one for the login and the second for the welcome. Now I want to present the Firstname and the Lastname of the connected user near to the hello in the welcome screen.

I tried many things but none of them worked so I'm asking for you help. I just started to learn GUI:

The login code:

import java.awt.EventQueue;
import java.sql.*;
import javax.swing.*;
import java.awt.Font;
import java.awt.Image;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;

public class Login {

    private JFrame frame;
    private JLabel MainLogo;
    String  Firstname=null; 
    String  Lastname=null;


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

    /**
     * Create the application.
     */
    Connection connected = null;
    private JTextField UsernameFiled;
    private JPasswordField passwordField;

    public Login() {
        initialize();

        connected = DBConnection.DBconnector();

    }

    /**
     * Initialize the contents of the frame.
     */
    private void initialize() {
        frame = new JFrame();
        frame.setBounds(100, 100, 560, 256);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().setLayout(null);

        JLabel lblNewLabel = new JLabel("UserName: ");
        lblNewLabel.setFont(new Font("Tahoma", Font.BOLD, 20));
        lblNewLabel.setBounds(160, 11, 140, 50);
        frame.getContentPane().add(lblNewLabel);

        JLabel lblPassword = new JLabel("PassWord: ");
        lblPassword.setFont(new Font("Tahoma", Font.BOLD, 20));
        lblPassword.setBounds(160, 72, 140, 40);
        frame.getContentPane().add(lblPassword);

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

                try {


                    String query = "Select * from Users where nickname=? and password=?";
                    PreparedStatement pst = connected.prepareStatement(query);
                    pst.setString(1, UsernameFiled.getText());
                    pst.setString(2, passwordField.getText());

                    ResultSet res = pst.executeQuery();
                    Firstname = res.getString("Firstname");
                    Lastname = res.getString("Lastname");
                    int c=0;

                    while(res.next()) {
                        c++;
                    }

                    if(c == 0) {
                        JOptionPane.showMessageDialog(null, "You didnt put any username or password!");
                    }
                    else if(c == 1) {
                        JOptionPane.showMessageDialog(null, "Hello to you, " + Firstname +" "+ Lastname);
                        frame.dispose();
                        UserPage UserFrame = new UserPage();
                        UserFrame.setVisible(true);

                    }else if( c > 1) {
                        JOptionPane.showMessageDialog(null, "Duplicate Username and Password");
                    }else {
                        JOptionPane.showMessageDialog(null, "Username and Password are inncorect...Try agian!");
                    }

                    pst.close();
                    res.close();

                }catch(Exception LoginError) {
                    JOptionPane.showMessageDialog(null, LoginError);

                }




            }
        });

        Loginbtn.setFont(new Font("Tahoma", Font.BOLD, 20));
        Loginbtn.setBounds(160, 148, 186, 40);
        frame.getContentPane().add(Loginbtn);

        UsernameFiled = new JTextField();
        UsernameFiled.setFont(new Font("Tahoma", Font.BOLD, 16));
        UsernameFiled.setBounds(310, 28, 186, 25);
        frame.getContentPane().add(UsernameFiled);
        UsernameFiled.setColumns(10);

        passwordField = new JPasswordField();
        passwordField.setFont(new Font("Tahoma", Font.BOLD, 16));
        passwordField.setBounds(310, 84, 186, 25);
        frame.getContentPane().add(passwordField);

        MainLogo = new JLabel("");
        Image imgs = new ImageIcon(this.getClass().getResource("/login.png")).getImage();
        MainLogo.setIcon(new ImageIcon(imgs));
        MainLogo.setBounds(10, 11, 128, 128);
        frame.getContentPane().add(MainLogo);
    }
}

The Welcome Code:

import java.awt.BorderLayout;
import java.awt.EventQueue;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;

import net.proteanit.sql.DbUtils;

import javax.swing.JLabel;
import javax.swing.JOptionPane;

import java.awt.Font;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

import java.sql.*;
import javax.swing.*;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;

public class UserPage extends JFrame {

    private JPanel contentPane;

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

    /**
     * Create the frame.
     */

    Connection connected=null;
    private JTable table;

    public UserPage() {
        connected=DBConnection.DBPreconnector();
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 576, 410);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        setContentPane(contentPane);
        contentPane.setLayout(null);

        JButton bntLoadData = new JButton("Show Users Data");
        bntLoadData.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {


                try {

                    String query = "Select ID,Age,Password,Firstname,Lastname from users";
                    PreparedStatement pst = connected.prepareStatement(query);

                    ResultSet res = pst.executeQuery();
                    table.setModel(DbUtils.resultSetToTableModel(res));


                } catch (Exception Error) {

                    Error.printStackTrace();
                }

            }
        });

        JLabel lblNewLabel = new JLabel("Hello,  "  + "The Username name");
        lblNewLabel.setFont(new Font("Tahoma", Font.BOLD, 18));
        lblNewLabel.setBounds(10, 11, 280, 19);
        contentPane.add(lblNewLabel);

        bntLoadData.setFont(new Font("Tahoma", Font.BOLD, 20));
        bntLoadData.setBounds(162, 102, 238, 23);
        contentPane.add(bntLoadData);

        table = new JTable();
        table.setBounds(28, 136, 508, 221);
        contentPane.add(table);
    }
}

Solution

In your code, you does not seem to load the username or password of the logged in user at the welcome frame. Either you will have to pass that from the login frame or you will have to re-query the database and get firstname and lastname.

I suggest, simply pass the firstname and lastname from welcome screen via constructor.

In successful login, simply pass the name in the constructor: Login code addition:

                } else if(c == 1) {
                    JOptionPane.showMessageDialog(null, "Hello to you, " + Firstname +" "+ Lastname);
                    frame.dispose();
                    UserPage UserFrame = new UserPage( Firstname, Lastname );
                    UserFrame.setVisible(true);
                }

In the welcome frame, add a constructor to handle this:

public UserPage(String loggedInFirstName, String loggedInLastName){
   // your remaining code
   JLabel lblNewLabel = new JLabel("Hello,  "  + loggedInFirstName + " " + loggedInLastName );
   // your remaining code.
}

A approach like this might work for your case and don't forget to mark the answer as accepted if this works for you