Program Menu Login dengan Database

Koneksi.java

import java.sql.*;
/**
 * Ini adalah class koneksinya 
 * @author Resa C.R
 */
public class Koneksi
{
    private static Connection koneksi;
    
    public static Connection getKoneksi()
    {
        if(koneksi == null)
        {
            try
            {
                DriverManager.registerDriver( new org.apache.derby.jdbc.ClientDriver());
                koneksi = DriverManager.getConnection("jdbc:derby://localhost:1527/Penjualan;user=root;password=root");
            }
            catch(Exception ex)
            {
                System.out.println("Gagal Koneksi ke Database");
                System.out.println(ex);
            }
        }
        return koneksi;
    }
}

MenuLogin.java

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.sql.*;
/**
 *
 * @author Resa C.R
 */
public class MenuLogin extends JFrame
{
    private JLabel lblLogin = new JLabel("Login : ");
    private JLabel lblUser = new JLabel("Username");
    private JTextField txtUser = new JTextField();
    private JLabel lblPasswd = new JLabel("Password");
    private JPasswordField pf = new JPasswordField();
    private JLabel lblGambar = new JLabel(new ImageIcon("src/Java/Penjualan/gambar/logo.png"));
    private JButton btnMasuk = new JButton("Masuk",new ImageIcon("src/Java/Penjualan/gambar/masuk.png"));
    private JButton btnBatal = new JButton("Batal",new ImageIcon("src/Java/Penjualan/gambar/batal.png"));
   
    //Konstruktor
    public MenuLogin()
    {
        setTitle("Login");
        setSize(630,500);
        setVisible(true);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLocationRelativeTo(null);
        setResizable(false);
        
        getContentPane().setLayout(null);
        
        lblGambar.setBounds(20,20,256,256);
        getContentPane().add(lblGambar);
        lblLogin.setBounds(460,100,100,25);
        getContentPane().add(lblLogin);
        lblUser.setBounds(450,135,100,25);
        getContentPane().add(lblUser);
        txtUser.setBounds(390,160,200,25);
        getContentPane().add(txtUser);
        lblPasswd.setBounds(450,195,100,25);
        getContentPane().add(lblPasswd);
        pf.setBounds(390,230,200,25);
        getContentPane().add(pf);
        btnMasuk.setBounds(320,280,130,64);
        getContentPane().add(btnMasuk);
        btnBatal.setBounds(470,280,130,64);
        getContentPane().add(btnBatal);
        
        btnMasuk.addActionListener(new ActionListener() 
        {
             @Override
            public void actionPerformed(ActionEvent act) 
            {
                try
                {
                String user = txtUser.getText();
                String passwd = pf.getText();
                if(user.equals(""))
                {
                    JOptionPane.showMessageDialog(null,"Username belum diisi","Pesan",JOptionPane.INFORMATION_MESSAGE);
                }
                else if(passwd.equals(""))
                {
                   JOptionPane.showMessageDialog(null,"Password belum diisi","Pesan",JOptionPane.INFORMATION_MESSAGE);  
                }
                Connection koneksi = Koneksi.getKoneksi();
                Statement state = koneksi.createStatement();
                String sql = "select * from APP.LOGIN where NAMA = '"+txtUser.getText()+"' and PASSWORD = '"+pf.getText()+"'";
                ResultSet rs = state.executeQuery(sql);
                boolean masuk = false;
                masuk = rs.next();
                    if(masuk)
                    {
                    JOptionPane.showMessageDialog(null,"Selamat Datang","Pesan",JOptionPane.PLAIN_MESSAGE);
                    setVisible(false);
                    }
                    else
                    {
                        JOptionPane.showMessageDialog(null,"Anda belum terdaftar di dalam database","Pesan",JOptionPane.INFORMATION_MESSAGE);
                        txtUser.setText("");
                        pf.setText("");
                        txtUser.requestFocus();
                    }
                }
                catch(Exception ex)
                {
                    System.out.println(ex);
                }
                  
            }
        });
        
     }//Akhir Konstruktor


public static void main(String[] ar)
{
     new MenuLogin();
}

}