How to use : Java GUI Pass Variable / Class Between Frame

public class UserClass {
	
    public static String sUsername;
    public static String sName;
    
    // Username
    public void setUsername(String username){
    	sUsername = username;

    }
    public static String getUsername(){
    	return sUsername;

    }
    
    // Name
    public void setName(String name){
    	sName = name;
    }
    public static String getName(){
    	return sName;
    }
    
}

// set Variable to Class
UserClass user = new UserClass();
user.setUsername(rec.getString("Username"));
user.setName(rec.getString("Name"));

// get Username & Name from Class
UserClass user = new UserClass();
lblUsername.setText(user.getUsername());
lblName.setText(user.getName());

CREATE TABLE `member` (
  `UserID` int(4) unsigned zerofill NOT NULL auto_increment,
  `Username` varchar(20) NOT NULL,
  `Password` varchar(20) NOT NULL,
  `Email` varchar(150) NOT NULL,
  `Name` varchar(250) NOT NULL,
  PRIMARY KEY  (`UserID`),
  UNIQUE KEY `User` (`Username`)
) ENGINE=MyISAM  DEFAULT CHARSET=utf8 AUTO_INCREMENT=4 ;

-- 
-- dump ตาราง `member`
-- 

INSERT INTO `member` VALUES (0001, 'weerachai', 'weerachai@1', '[email protected]', 'Weerachai Nukitram');
INSERT INTO `member` VALUES (0002, 'surachai', 'surachai@2', '[email protected]', 'Surachai Sirisart');
INSERT INTO `member` VALUES (0003, 'adisorn', 'adisorn@3', '[email protected]', 'Adisorn Bonsong');

package com.java.myapp;

public class UserClass {
	
    public static String sUsername;
    public static String sName;
    
    // Username
    public void setUsername(String username){
    	sUsername = username;

    }
    public static String getUsername(){
    	return sUsername;

    }
    
    // Name
    public void setName(String name){
    	sName = name;
    }
    public static String getName(){
    	return sName;
    }
    
}

package com.java.myapp;

import javax.swing.JButton;
import javax.swing.JDialog;

import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JTextField;
import javax.swing.JLabel;
import javax.swing.JPasswordField;

public class LoginDialog extends JDialog {

	public String sUsername;
	public String sPassword;
	
	public static void main(String[] args) {
		try {
			LoginDialog dialog = new LoginDialog();
			dialog.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
			dialog.setVisible(true);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	public LoginDialog() {
		setBounds(100, 100, 296, 175);
		setTitle("Login Username/Password");
		setResizable(false);
		setLocationRelativeTo(null);
		getContentPane().setLayout(null);
	
		
		// Label Username
		JLabel lblUsername = new JLabel("Username");
		lblUsername.setBounds(33, 25, 82, 14);
		getContentPane().add(lblUsername);
		
		// Label Password
		JLabel lblPassword = new JLabel("Password");
		lblPassword.setBounds(33, 56, 64, 14);
		getContentPane().add(lblPassword);
		
		// Input Username
		final JTextField username = new JTextField();
		username.setBounds(125, 22, 101, 20);
		getContentPane().add(username);
		
		// Input Password
		final JPasswordField password = new JPasswordField();
		password.setBounds(125, 53, 101, 20);
		getContentPane().add(password);
		
		// Button OK
		JButton btnOK = new JButton("OK");
		btnOK.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				sUsername = username.getText();
				sPassword = new String(password.getPassword()); 
				dispose();
			}
		});
		btnOK.setBounds(70, 102, 78, 23);
		getContentPane().add(btnOK);
		
		// Button Cancel
		JButton btnCancel = new JButton("Cancel");
		btnCancel.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				sUsername = "";
				sPassword = "";
				System.exit(0);
			}
		});
		btnCancel.setBounds(158, 102, 74, 23);
		getContentPane().add(btnCancel);
		
		
	}
}

package com.java.myapp;

import java.awt.EventQueue;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
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 java.awt.Font;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;

public class MyForm extends JFrame {

	public static String userName;
	public static String passWord;
	static JLabel lblWelcome;
	
	public static void main(String[] args) {
		EventQueue.invokeLater(new Runnable() {
			public void run() {
				MyForm form = new MyForm();
				form.setVisible(true);
			}
		});
	}
	
	
	public MyForm() {
            
		// Create Form Frame
		super("ThaiCreate.Com Tutorial");
		setSize(679, 385);
		setLocation(500, 280);
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		getContentPane().setLayout(null);
		
		// Label Welcome
		lblWelcome = new JLabel("lblWelcome",JLabel.CENTER);
		lblWelcome.setFont(new Font("Tahoma", Font.PLAIN, 20));
		lblWelcome.setBounds(168, 110, 336, 25);
		getContentPane().add(lblWelcome);
		
		// Button Open Form
		JButton btnGoToNext = new JButton("Go to Next Windows");
		btnGoToNext.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent arg0) {
				MyForm2 form2 = new MyForm2();
				form2.setVisible(true);
			}
		});
		btnGoToNext.setBounds(260, 210, 172, 23);
		getContentPane().add(btnGoToNext);
		
		// When Frame Loaded
		addWindowListener(new WindowAdapter() {
			@Override
			public void windowOpened(WindowEvent e) {
				OpenDialog();
			}
		});
					
	}
	
	public static Boolean getLogin() {
		
		Connection connect = null;
		PreparedStatement pre = null;
		Boolean status = false;
		
		try {
			Class.forName("com.mysql.jdbc.Driver");

			connect =  DriverManager.getConnection("jdbc:mysql://localhost/mydatabase" +
					"?user=root&password=root");	
			
			String sql = " SELECT * FROM  member " +
					" WHERE Username = ? " +
					" AND Password = ? ";
			pre = connect.prepareStatement(sql);
			pre.setString(1, userName);
			pre.setString(2, passWord);

			ResultSet rec = pre.executeQuery();
			if(rec.next()) {
				lblWelcome.setText("Welcome : " + rec.getString("Name"));
				
				// Passing Variable to Class
				UserClass user = new UserClass();
				user.setUsername(rec.getString("Username"));
				user.setName(rec.getString("Name"));
				
				status = true;
			} else {
     		JOptionPane.showMessageDialog(null, "Incorrect Username/Password");
			}
             
		} catch (Exception e) {
			// TODO Auto-generated catch block
			JOptionPane.showMessageDialog(null, e.getMessage());
			e.printStackTrace();
		}
		
		try {
			if(pre != null) {
				pre.close();
				connect.close();
			}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			System.out.println(e.getMessage());
			e.printStackTrace();
		}
		
		return status;
	}
	
	
	public static void OpenDialog() {

		LoginDialog dialog = new LoginDialog();
		dialog.setModal(true);
		dialog.setVisible(true);
	
		
		userName = dialog.sUsername;
		passWord =  dialog.sPassword;
		
		// Check Login
		if(!getLogin()){
			OpenDialog(); // Login Again
		}
		
	}
}

package com.java.myapp;

import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JLabel;
import java.awt.Font;
import javax.swing.SwingConstants;

public class MyForm2 extends JFrame {

	private JPanel contentPane;

	/**
	 * Launch the application.
	 */
	public static void main(String[] args) {
		EventQueue.invokeLater(new Runnable() {
			public void run() {
				try {
					MyForm2 frame = new MyForm2();
					frame.setVisible(true);
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		});
	}

	/**
	 * Create the frame.
	 */
	public MyForm2() {
		super("ThaiCreate.Com Tutorial");
		setSize(679, 385);
		setLocation(500, 280);
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		getContentPane().setLayout(null);
		
		// Username
		JLabel lblUsername = new JLabel("Username");
		lblUsername.setHorizontalAlignment(SwingConstants.CENTER);
		lblUsername.setFont(new Font("Tahoma", Font.PLAIN, 18));
		lblUsername.setBounds(186, 108, 307, 14);
		getContentPane().add(lblUsername);
		
		// Name
		JLabel lblName = new JLabel("Name");
		lblName.setHorizontalAlignment(SwingConstants.CENTER);
		lblName.setFont(new Font("Tahoma", Font.PLAIN, 18));
		lblName.setBounds(186, 162, 307, 14);
		getContentPane().add(lblName);
		
		// get Username & Name from Class
		UserClass user = new UserClass();
		lblUsername.setText(user.getUsername());
		lblName.setText(user.getName());
		
	}
}