public class LoginCumReg implements ActionListener,KeyListener {
    private JFrame form;
    private JTextField txtunm;
    private JTextField txtnm;
    private JTextField txteml;
    private JButton cmdcreate;
    private JPasswordField txtpass;
    private JPasswordField txtpassreg;
    private JButton cmdok;
    private JLabel lblunm;
    private JLabel lblpass;
    private JLabel lbleml;
    private JLabel lblpassreg;
    private JLabel lblnm;
    private JPanel panel_1;
public LoginCumReg() {
    // construct components
    form = new JFrame("Sign Up");
    form.getContentPane().setFont(
            new Font("Plantagenet Cherokee", Font.BOLD, 18));
    txtunm = new JTextField(5);
    txtunm.addKeyListener(this);
    txtunm.setBounds(637, 55, 100, 25);
    txtnm = new JTextField(5);
    txtnm.setBounds(637, 228, 100, 25);
    txteml = new JTextField(5);
    txteml.setBounds(637, 264, 100, 25);
    cmdcreate = new JButton("Create Account");
    cmdcreate.setBounds(527, 350, 188, 25);
    txtpass = new JPasswordField(5);
    txtpass.setBounds(637, 91, 100, 25);
    txtpassreg = new JPasswordField(5);
    txtpassreg.setBounds(637, 300, 100, 25);
    cmdok = new JButton("OK");
    cmdok.setBounds(527, 139, 100, 25);
    lblunm = new JLabel("UserName");
    lblunm.setBounds(527, 55, 73, 25);
    lblpass = new JLabel("Password");
    lblpass.setBounds(527, 91, 100, 25);
    lbleml = new JLabel("Email ID");
    lbleml.setBounds(527, 264, 100, 25);
    lblpassreg = new JLabel("Password");
    lblpassreg.setBounds(527, 300, 100, 25);
    lblnm = new JLabel("Full Name");
    lblnm.setBounds(527, 228, 100, 25);

    // form.setResizable(false);

    // adjust size and set layout
    form.setPreferredSize(new Dimension(800, 450));

    form.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    form.getContentPane().setLayout(null);

    // add components
    form.getContentPane().add(txtunm);
    form.getContentPane().add(txtnm);
    form.getContentPane().add(txteml);
    form.getContentPane().add(cmdcreate);
    form.getContentPane().add(txtpass);
    form.getContentPane().add(txtpassreg);
    form.getContentPane().add(cmdok);
    form.getContentPane().add(lblunm);
    form.getContentPane().add(lblpass);
    form.getContentPane().add(lbleml);
    form.getContentPane().add(lblpassreg);
    form.getContentPane().add(lblnm);

    cmdcreate.setActionCommand("Create Account");
    cmdcreate.addActionListener(this);
    cmdok.setActionCommand("Login");

    JPanel panel = new JPanel();
    panel.setBounds(502, 29, 254, 154);
    panel.setFont(new Font("Palatino Linotype", Font.PLAIN, 14));
    panel.setBorder(new TitledBorder(new EtchedBorder(EtchedBorder.RAISED,
            null, null), "LOGIN", TitledBorder.LEADING, TitledBorder.TOP,
            null, null));
    panel.setBackground(SystemColor.controlHighlight);
    form.getContentPane().add(panel);

    panel_1 = new JPanel();
    panel_1.setBounds(500, 204, 254, 186);
    panel_1.setFont(new Font("Palatino Linotype", Font.PLAIN, 14));
    panel_1.setBorder(new TitledBorder(new EtchedBorder(
            EtchedBorder.RAISED, null, null), "SIGN UP",
            TitledBorder.LEADING, TitledBorder.TOP, null, null));
    panel_1.setBackground(SystemColor.controlHighlight);
    form.getContentPane().add(panel_1);

    JLabel lblNewLabel = new JLabel("New label");
    lblNewLabel.setBounds(91, 139, 286, 101);
    lblNewLabel.setIcon(new ImageIcon(
            "C:\\Users\\JAsh\\Desktop\\Projects\\JAsh.png"));
    form.getContentPane().add(lblNewLabel);

    JPanel panel_2 = new JPanel();
    panel_2.setBounds(77, 118, 315, 145);
    panel_2.setBorder(new EtchedBorder(EtchedBorder.RAISED,
            SystemColor.activeCaptionBorder, SystemColor.menu));
    panel_2.setBackground(SystemColor.controlHighlight);
    form.getContentPane().add(panel_2);
    cmdok.addActionListener(this);

    form.setResizable(false);
    form.pack();
    form.setVisible(true);
    System.out.println("const..");
}

public static void main(String[] args) {
    new LoginCumReg();
}

@Override
public void actionPerformed(ActionEvent ae) {
    // TODO Auto-generated method stub

    if (ae.getActionCommand().equals("Create Account")) {
        new Registration(txtnm.getText(), txteml.getText(), new String(
                txtpassreg.getPassword()));
        form.setVisible(false);
    }

    if (ae.getActionCommand().equals("Login")) {
        try {
            if (txtunm.getText().equalsIgnoreCase("admin")
                    && new String(txtpass.getPassword()).equals("admin")) {
                form.setVisible(false);
                new Admin();
            } else {
                DataBase db = new DataBase();
                db.connect();
                String sql = "SELECT * FROM LOGIN WHERE USERNAME='"
                        + txtunm.getText() + "'";
                ResultSet rs = db.getDDL(sql);
                boolean found = false;
                while (rs.next()) {
                    if (rs.getString("Password").equals(
                            new String(txtpass.getPassword()))) {
                        found = true;
                        form.setVisible(false);
                        String name = rs.getString("FullName");
                        Session.startSession(txtunm.getText(), name);
                        new FacultyWelcome();
                    }
                }
                if (!found)
                    JOptionPane.showMessageDialog(new JFrame(),
                            "Invalid Credentials");
                db.close();
            }
        } catch (Exception e) {
        }
    }

}

@Override
public void keyPressed(KeyEvent arg0) {
    // TODO Auto-generated method stub
}

@Override
public void keyReleased(KeyEvent arg0) {
    // TODO Auto-generated method stub

}

@Override
public void keyTyped(KeyEvent arg0) {
    // TODO Auto-generated method stub
//  JOptionPane.showMessageDialog(new JFrame(), arg0.getKeyChar()+"-"+arg0.getKeyCode());

}

}

Der obige Code funktioniert perfekt auf dem Laptop meines Freundes und löst diesen Fehler auf meinem Laptop aus. Ich habe den Code auf Eclipse Juno mit Java 7 ausgeführt. Ich habe auch viele Java-Programme auf meinem Laptop getestet und ausgeführt, alles funktioniert gut. Dies ist das einzige Programm, das einen solchen Fehler verursacht. Dies ist mein letztes Jahr Projekt und ich brauche es, um an meinem Laptop zu arbeiten. Ich werde jedem dankbar sein, der hilft