void Masuk(){
        try{
            Mysqlkoneksi kon = new Mysqlkoneksi();
            Connection con = kon.getConnection();
            Statement st = con.createStatement();
            String sqllogin = "SELECT * FROM user WHERE username='"+txt_username.getText()+"'";
            ResultSet rs = st.executeQuery(sqllogin);
            String sql_username = null;
        String sql_password = null;
        if(rs.next()){
        sql_username = rs.getString("username");
        sql_password = rs.getString("password");

        if(sql_username.equals(txt_username.getText())&&sql_password.equals(txt_passwd.getText())){
                            JOptionPane.showMessageDialog(this, "Berhasil masuk");
                this.setVisible(false);
        }else
                {
                    JOptionPane.showMessageDialog(this, "USERNAME atau PASSWORD anda salah"," PERINGATAN ", JOptionPane.ERROR_MESSAGE);
            }
            }
            else{
                    JOptionPane.showMessageDialog(this, "USERNAME atau PASSWORD anda salah"," PERINGATAN ", JOptionPane.ERROR_MESSAGE);
            }

             rs.close();
             con.close();
        }catch(SQLException e){
            JOptionPane.showMessageDialog(null, "USERNAME atau PASSWORD  anda SALAH", "PESAN", JOptionPane.ERROR_MESSAGE);
        }
    }

    void Kosong(){

        if(txt_username.getText().equals("")){
           JOptionPane.showMessageDialog(this, " USERNAME atau PASSWORD belum diisi", "PESAN", JOptionPane.ERROR_MESSAGE);
        }else if(txt_passwd.getPassword().equals("")){
           JOptionPane.showMessageDialog(this, " USERNAME atau PASSWORD belum diisi", "PESAN", JOptionPane.ERROR_MESSAGE);
        }else{
            Masuk();
        }
    }