Having trouble passing a getter method in a PreparedStatement

Question

Basically I've got it so that the user fills in their name, dob etc and when they click on register it inserts their information in a registrations table. However, I'm having trouble getting this working (NullPointerException) so any help would be greatly appreciated :)
RegisterDetails.java
public void writeToTbl() throws SQLException, ClassNotFoundException {
          DBase d = new DBase();
          GUI g = new GUI();
          i = 0;
          String regStr = "INSERT INTO REGISTRATION VALUES(?,?,?,?,?,?,?,?)";
          PreparedStatement st = d.getConnection().prepareStatement(regStr);          
          st.setInt(1, i);
          st.setString(2, g.getName()); //Exception error points to this line
          st.setString(3, g.getDOB());
          st.setString(4, g.getRoad());
          st.setString(5, g.getCity());
          st.setString(6, g.getCounty());
          st.setString(7, g.getPhone());
          st.setString(8, g.getEmail());
          st.executeUpdate();
     }GUI.java
btnReg.addActionListener(new ActionListener() {
               public void actionPerformed(ActionEvent ev) {               
                    if (ev.getSource() == btnReg && (agree.isSelected())) {
                         writeToFile(f, bWriter);
                         RegisterDetails reg = new RegisterDetails();
                         try {
                              reg.writeToTbl(); //Exception error points to this line
                         } catch (SQLException e) {
                              e.printStackTrace();
                         } catch (ClassNotFoundException e) {
                              e.printStackTrace();
                    else {
// JTextFields return their results
public String getName() {
          return name.getText(); //Exception error points to this line
     public String getDOB() {
          return dob.getText();
     public String getRoad() {
          return road.getText();
     public String getCity() {
          return city.getText();
     public String getCounty() {
          return county.getText();
     public String getPhone() {
          return phoneNo.getText();
     public String getEmail() {
          return email.getText();So essentially I'm trying to get the information from the textfields and insert it into the registrations table but nothing seems to work. I've followed numerous tutorials on how to do it, but all of them use "fixed" values e.g., setString(1, "James") etc but I need the value of the JTextFields as they will be different every time. I'm completely at a loss with this at the moment so any help would be magnificent. :-)
Thank you!

Answer 1

so any help would be magnificent.Write a class that accepts the values that you want to insert. I would suggest passing an ArrayList. It opens the connection, does the insert, closes the statement and the connection.
It does NOT have any GUI code in it.
You then debug that class and verify it works.
THEN, after you have verified it works, you write ANOTHER class that does the gui. It uses the class above to do the database work.