mainclass.java

Example of Derby DB usage. Simple student system implemented using Swing.

            }
            catch(Exception ex)
            {
                JOptionPane.showMessageDialog(frame,"GPA must be a float number!");
                return;
            }
        }

        if(name.length()==0)
        {
            JOptionPane.showMessageDialog(frame,"Please enter the name!");
            return;
        }

        DerbyDriver drv = new DerbyDriver();
        Connection conn = null;
        try
        {
            StudentRecord sr = new StudentRecord(id, name, grade);
            conn = openConnection();
            int num = drv.updateStudentRecord(conn, id, sr);
            if(num==0)
                JOptionPane.showMessageDialog(frame,"Can't find record for updating with ID="+sid+"!");
            else
                JOptionPane.showMessageDialog(frame,"Record with ID="+sid+" updated successfully!");
        }
        catch(Exception ex)
        {
            ex.printStackTrace();
        }
        finally
        {
            try
            {
                if(conn!=null)
                    conn.close();
            }
            catch(Exception ex)
            {
                ex.printStackTrace();
            }
        }
    }

    private boolean isNum(char chr)
    {
        try
        {
            StringBuffer sb = new StringBuffer();
            sb.append(chr);
            Integer.parseInt(sb.toString());
        }
        catch(Exception ex)
        {
            return false;
        }
        return true;
    }

    public void setPsw()
    {
        System.out.println("Set new password");
        String psw = pswField.getText();
        int letters = 0;
        int nums = 0;

        for(int i=0; i<psw.length(); i++)
            if(isNum(psw.charAt(i)))
                nums++;
            else
                letters++;

        if(nums<3)
        {
            JOptionPane.showMessageDialog(frame, "You password must contain at least 3 digits!");
            return;
        }

        if(letters<5)
        {
            JOptionPane.showMessageDialog(frame, "You password must contain at least 5 letters!");
            return;
        }


        String oldPsw = lastUser.getPassword();
        int differs=0;
        int len = Math.min(oldPsw.length(), psw.length());

        for(int i=0; i<len; i++)
        {
            if(psw.charAt(i)!=oldPsw.charAt(i))
                differs++;
        }

        if(differs<2)
        {
            JOptionPane.showMessageDialog(frame, "Old and new password must differ more than 1 characters!");
            return;
        }

        Connection conn = null;
        try
        {
            DerbyDriver drv = new DerbyDriver();
            conn = openConnection();
            UserRecord newData = new UserRecord(lastUser.getName(), psw, 3);
            drv.updateUserRecord(conn, lastUser.getName(), newData);
            userField.setText("");
            pswField.setText("");
            setLoginMode();
            setLoggedOut();
        }
        catch (Exception ex)
        {
            ex.printStackTrace();
        }
        finally
        {
            try
            {
                if(conn!=null)
                    conn.close();
            }
            catch(Exception ex)
            {
                ex.printStackTrace();
            }
        }
    }

    public void actionPerformed(ActionEvent e)
    {
        String cmd = e.getActionCommand();
        if("login".equals(cmd))
            login();

        if("fetch".equals(cmd))
            if(isLoggegOn)
            {
                fetch();
            }
            else
            {
                JOptionPane.showMessageDialog(frame,"You are not logged in!");
            }

        if("clear".equals(cmd))
               clearStudFields();

        if("logout".equals(cmd))
            if(isLoggegOn)
            {
                setLoggedOut();
            }
            else
            {
                JOptionPane.showMessageDialog(frame,"You are not logged in!");
            }

        if("update".equals(cmd))
            if(isLoggegOn)
            {
                update();
            }
            else
            {
                JOptionPane.showMessageDialog(frame,"You are not logged in!");
            }

        if("set_psw".equals(cmd))
            setPsw();
    }

    private void createAndShowGUI()
    {
        Container cnt = frame.getContentPane();

        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        cnt.setLayout(new GridBagLayout());
        GridBagConstraints c = new GridBagConstraints();
        c.fill = GridBagConstraints.HORIZONTAL;

        userField.setSize(100,20);
        userField.setLocation(100,100);
        pswField.setSize(100,20);
        pswField.setLocation(100,150);

        cnt.add(loginLabel, getGBC(c,1,0,1,1));
        cnt.add(loginLabel2, getGBC(c,1,0,1,1));
        cnt.add(unLabel, getGBC(c,0,1,1,1));
        cnt.add(userField, getGBC(c,0,2,3,1));
        cnt.add(pswLabel, getGBC(c,0,3,1,1));
        cnt.add(pswLabel2, getGBC(c,0,3,1,1));
        cnt.add(pswField, getGBC(c,0,4,3,1));
        cnt.add(loginButton,getGBC(c,1,5,1,1));
        cnt.add(logoutButton,getGBC(c,1,5,1,1));
        cnt.add(setButton,getGBC(c,1,5,1,1));
        cnt.add(rlLabel,getGBC(c,0,6,3,1));

        pan.setBorder(BorderFactory.createBevelBorder(BevelBorder.RAISED));

        c.fill = GridBagConstraints.VERTICAL;
        cnt.add(pan, getGBC(c,3,0,1,8));
        c.fill = GridBagConstraints.HORIZONTAL;
        cnt.add(sdLabel, getGBC(c,5,0,2,1));
        cnt.add(sidLabel, getGBC(c,4,2,1,1));
        cnt.add(idField, getGBC(c,5,2,2,1));
        cnt.add(fetchButton, getGBC(c,7,2,1,1));
        cnt.add(clearButton, getGBC(c,7,3,1,1));
        cnt.add(nameLabel,  getGBC(c,4,4,1,1));
        cnt.add(nameField,  getGBC(c,5,4,2,1));
        cnt.add(gpaLabel,  getGBC(c,4,5,1,1));
        cnt.add(gpaField,  getGBC(c,5,5,2,1));
        cnt.add(updateButton,  getGBC(c,7,5,1,1));

        frame.setBounds(0,0,600,200);
        //Display the window.
        //frame.pack();
        frame.setVisible(true);

        clearButton.setActionCommand("clear");
        clearButton.addActionListener(this);
        logoutButton.setActionCommand("logout");
        logoutButton.addActionListener(this);
        loginButton.setActionCommand("login");
        loginButton.addActionListener(this);
        fetchButton.setActionCommand("fetch");
        fetchButton.addActionListener(this);
        updateButton.setActionCommand("update");
        updateButton.addActionListener(this);
        setButton.setActionCommand("set_psw");
        setButton.addActionListener(this);
        setLoginMode();
        setLoggedOut();
    }

    public Connection openConnection()
    {
        Connection conn = null;
        try
        {
            DerbyDriver drv = new DerbyDriver();
            conn = drv.getConnection(DerbyDriver.DB_DRIVER, DerbyDriver.DB_NAME);
            if(conn==null)
                throw new Exception("Error creating DB connection!");
        }
        catch (Exception ex)
        {
            ex.printStackTrace();
        }
        return conn;
    }

    public void testDB()
    {
        Connection conn = null;
        try
        {
            DerbyDriver drv = new DerbyDriver();
            conn = openConnection();
            drv.printDB(conn);
        }
        catch (Exception ex)
        {
            ex.printStackTrace();
        }
        finally
        {
            try
            {
                if(conn!=null)
                    conn.close();
            }
            catch(Exception ex)
            {
                ex.printStackTrace();
            }
        }
    }

    public static void main(String[] args)
    {
        //Schedule a job for the event-dispatching thread:
        //creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(
                new Runnable()
                {
                    public void run()
                    {
                        MainClass mc = new MainClass();
                        mc.testDB();
                        mc.createAndShowGUI();
                    }
                }
        );
    }

}