mainclass.java

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

import javax.swing.*;
import javax.swing.border.BevelBorder;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.sql.Connection;

public class MainClass implements ActionListener
{
    static
    {
        JFrame.setDefaultLookAndFeelDecorated(true);
    }

    private static final String NUM_OF_LOGINS = "Number of remaining logins: ";
    private static final String LOGIN_PANEL = "LOGIN PANEL";
    JLabel loginLabel = new JLabel(LOGIN_PANEL);
    JLabel loginLabel2 = new JLabel("Your password is expired!");
    JLabel unLabel = new JLabel("Username");
    JLabel pswLabel = new JLabel("Password");
    JLabel pswLabel2 = new JLabel("Enter new password:");
    JTextField userField = new JTextField("");
    JTextField pswField = new JTextField("");
    JButton loginButton = new JButton("Login");
    JButton logoutButton = new JButton("Logout");
    JButton setButton = new JButton("Set new password");
    JLabel rlLabel = new JLabel(NUM_OF_LOGINS);
    JLabel sdLabel = new JLabel("STUDENT DATA");
    JLabel sidLabel = new JLabel("Student ID");
    JLabel nameLabel = new JLabel("Name");
    JLabel gpaLabel = new JLabel("GPA");
    JTextField idField = new JTextField("");
    JTextField nameField = new JTextField("");
    JTextField gpaField = new JTextField("");
    JButton fetchButton = new JButton("Fetch Record");
    JButton clearButton = new JButton("Clear search fields");
    JButton updateButton = new JButton("Update Record");
    JPanel pan = new JPanel();
    JFrame frame = new JFrame("Login test");

    boolean isLoggegOn = false;
    UserRecord lastUser = null;
    int lastStudent = 0;

    /**
     * Create the GUI and show it.  For thread safety,
     * this method should be invoked from the
     * event-dispatching thread.
     */
    private static GridBagConstraints getGBC(GridBagConstraints c, int cell_x, int cell_y, int cells_w, int cells_h)
    {
        c.gridx = cell_x;
        c.gridy = cell_y;
        c.gridwidth = cells_w;
        c.gridheight = cells_h;
        c.weightx=5;
        return c;
    }

    private void setLoginMode()
    {
        loginLabel.setVisible(true);
        loginLabel2.setVisible(false);
        unLabel.setVisible(true);
        userField.setVisible(true);
        pswLabel.setVisible(true);
        pswLabel2.setVisible(false);
        loginButton.setVisible(true);
        setButton.setVisible(false);
    }

    private void setNewPswMode()
    {
        loginLabel.setVisible(false);
        loginLabel2.setVisible(true);
        unLabel.setVisible(false);
        userField.setVisible(false);
        pswLabel.setVisible(false);
        pswLabel2.setVisible(true);
        loginButton.setVisible(false);
        setButton.setVisible(true);
    }

    private void setLoggedOn()
    {
        isLoggegOn=true;
        loginLabel.setText(LOGIN_PANEL+" (Logged in)");
        loginButton.setVisible(false);
        logoutButton.setVisible(true);
    }

    private void setLoggedOut()
    {
        isLoggegOn=false;
        loginLabel.setText(LOGIN_PANEL);
        userField.setText("");
        pswField.setText("");
        loginButton.setVisible(true);
        logoutButton.setVisible(false);
        rlLabel.setText(NUM_OF_LOGINS);
    }

    public void login()
    {
        DerbyDriver drv = new DerbyDriver();
        Connection conn = null;
        try
        {
            conn = openConnection();
            String name = userField.getText();
            String psw = pswField.getText();
            UserRecord sr = new UserRecord(name, null, -1);
            java.util.List res = drv.getUserRecords(conn, sr);
            if(res.size()>0)
            {
                sr = (UserRecord)res.get(0);
                if(!sr.getPassword().equals(psw))
                {
                    JOptionPane.showMessageDialog(frame,"Invalid password.");
                    return;
                }
                sr = (UserRecord)res.get(0);
                rlLabel.setText(NUM_OF_LOGINS+sr.getLoginAtt());
                if(sr.getLoginAtt()==0)
                {
                    lastUser = sr;
                    setNewPswMode();
                    return;
                }
                else
                {
                    UserRecord newSr = new UserRecord(sr.getName(), sr.getPassword(), sr.getLoginAtt()-1);
                    rlLabel.setText(NUM_OF_LOGINS+(sr.getLoginAtt()-1));
                    drv.updateUserRecord(conn, sr.getName(), newSr);
                    lastUser = newSr;
                    setLoggedOn();
                }
            }
            else
            {
                JOptionPane.showMessageDialog(frame,"Invalid username.");
                return;
            }

        }
        catch(Exception ex)
        {
            ex.printStackTrace();
        }
        finally
        {
            try
            {
                if(conn!=null)
                    conn.close();
            }
            catch(Exception ex)
            {
                ex.printStackTrace();
            }
        }
    }

    private void clearStudFields()
    {
        idField.setText("");
        nameField.setText("");
        gpaField.setText("");
    }

    public void fetch()
    {
        if(!isLoggegOn)
        {
            clearStudFields();
            return;
        }
        String sid = idField.getText();
        String name = nameField.getText();
        String sgpa = gpaField.getText();

        if(sid.length()+name.length()+sgpa.length()==0)
        {
            JOptionPane.showMessageDialog(frame,"Please enter any data for record fetching!");
            return;
        }

        float grade = -1;
        int id=-1;

        if(sid.length()>0)
        {
            try
            {
                id = Integer.parseInt(sid);
            }
            catch(Exception ex)
            {
                JOptionPane.showMessageDialog(frame,"ID must be a number!");
                return;
            }
        }

        if(sgpa.length()>0)
        {
            try
            {
                grade = Float.parseFloat(sgpa);
            }
            catch(Exception ex)
            {
                JOptionPane.showMessageDialog(frame,"GPA must be a float number!");
                return;
            }
        }

        DerbyDriver drv = new DerbyDriver();
        Connection conn = null;
        try
        {
            conn = openConnection();
            StudentRecord srec = null;

            srec = new StudentRecord(id, name, grade);
            java.util.List res = drv.getStudentRecords(conn, id, srec);

            if(res!=null)
                if(res.size()>0)
                {
                    StudentRecord sr = (StudentRecord)res.get(0);
                    nameField.setText(sr.getName());
                    idField.setText(String.valueOf(sr.getId()));
                    gpaField.setText(String.valueOf(sr.getGrade()));
                    lastStudent = sr.getId();
                    return;
                }

           StringBuffer sb = new StringBuffer("There is no student record with ");

           if(id>-1)
            sb.append("ID=").append(id).append(" ");

            if(name.length()>0)
             sb.append("Name='").append(name).append("' ");

            if(sgpa.length()>0)
             sb.append("GPA=").append(sgpa).append(" ");

           JOptionPane.showMessageDialog(frame,sb.toString());
           return;
        }
        catch(Exception ex)
        {
            ex.printStackTrace();
        }
        finally
        {
            try
            {
                if(conn!=null)
                    conn.close();
            }
            catch(Exception ex)
            {
                ex.printStackTrace();
            }
        }
}

    public void update()
    {
        String sid = idField.getText();
        String name = nameField.getText();
        String sgpa = gpaField.getText();
        int id=-1;
        float grade = -1;

        if(sid.length()>0)
        {
            try
            {
                id = Integer.parseInt(sid);
            }
            catch(Exception ex)
            {
                JOptionPane.showMessageDialog(frame,"ID must be a number!");
                return;
            }
        }
        else
        {
            JOptionPane.showMessageDialog(frame,"You must enter ID of record to be updated!");
            return;
        }

        if(sgpa.length()>0)
        {
            try
            {
                grade = Float.parseFloat(sgpa);