I am new to Programming and I'm getting some errors when trying to create a login system using java. I'm using Netbeans to create the GUI, ask for user details, and save it in a database. But when I try to login it gives me a null pointer exception which I can't seem to resolve. Here is the programme I wrote:
public class Final_3_ClientAccountCreation extends javax.swing.JFrame {
/**
* Creates new form ClientAccountCreation
*/
String id, fullName, contactNumber, email, district, postalCode, gender, nameWithInitials, userName, password, confirmPassword;
String accType;
Date birthDate;
Connection conn = null;
static int accNo = 211234546;
public Final_3_ClientAccountCreation() {
initComponents();
jTabbedPane1.setEnabledAt(1, false);
jTabbedPane1.setEnabledAt(2, false);
}
private void switchToPersonalInfoPanel() {
jTabbedPane1.setSelectedIndex(0);
}
private void switchToBankAccountPanel() {
jTabbedPane1.setEnabledAt(1, true);
jTabbedPane1.setSelectedIndex(1);
}
private void switchToOnlineAccountPanel() {
jTabbedPane1.setEnabledAt(2, true);
jTabbedPane1.setSelectedIndex(2);
}
private void getClientInfo() {
this.id = regID.getText();
this.fullName = regFullName.getText();
this.birthDate = regBirthDate.getDate();
this.contactNumber = regContactNumber.getText();
this.email = regEmail.getText();
this.district = (String) regDistrict.getSelectedItem();
this.postalCode = regPostalCode.getText();
if (regIsMale.isSelected()) {
this.gender = "Male";
} else {
this.gender = "Female";
}
this.nameWithInitials = getNameWithInitials(fullName);
}
private void clearFields() {
regBirthDate.setDate(null);
regID.setText(null);
regFullName.setText(null);
regPostalCode.setText(null);
regEmail.setText(null);
regContactNumber.setText(null);
}
public static String getNameWithInitials(String name) {
String nameWithInitials = "";
String[] names = name.split("\\s+");
String lastName = names[names.length - 1];
for (int i = 0; i < names.length - 1; i++) {
nameWithInitials += Character.toUpperCase(names[i].charAt(0)) + ". ";
}
return nameWithInitials + lastName;
}
private void setBankAccPanelValues() {
accName.setText(nameWithInitials);
accBirthDate.setText(birthDate + "");
accContactNumber.setText(contactNumber);
accDistrict.setText(district);
accEmailAddress.setText(email);
accPostalCode.setText(postalCode);
regAccountNumber.setText(accNo + "");
}
private boolean verifyFields() {
getClientInfo();
if (id.equals("") || fullName.equals("") || birthDate.equals(null) || contactNumber.equals("") || email.equals("") || postalCode.equals("")) {
return false;
} else {
return true;
}
}
private boolean verifyUsernameandPassword() {
userName = regUserName.getText();
password = String.valueOf(regPassword.getPassword());
confirmPassword = String.valueOf(regConfirmPassword.getPassword());
if (userName.equals("") || password.equals("") || confirmPassword.equals("")) {
JOptionPane.showMessageDialog(null, "One or More Fields are Empty", "Empty Fields", 2);
return false;
} else if (password.equals(confirmPassword)) {
return true;
} else {
JOptionPane.showMessageDialog(null, "Passwords Don't Match!");
return false;
}
}
public boolean checkUsername() {
PreparedStatement st;
ResultSet rs;
boolean usernameDoesNotExist = true;
System.out.println("Hello");
try {
userName = regUserName.getText();
String query = ("SELECT * FROM `users` WHERE `username` = " + userName);
st = conn.prepareStatement(query);
System.out.println("Hi");
//st.setString(1, userName);
rs = st.executeQuery();
if (rs.next()) {
usernameDoesNotExist = false;
JOptionPane.showMessageDialog(null, "This Username is Already Taken, Choose Another One", "Username Failed", 2);
}
} catch (SQLException ex) {
Logger.getLogger(NewUserForm.class.getName()).log(Level.SEVERE, null, ex);
}
System.out.println(usernameDoesNotExist);
return usernameDoesNotExist;
}
/**
* This method is called from within the constructor to initialize the form.
* WARNING: Do NOT modify this code. The content of this method is always
* regenerated by the Form Editor.
*/
private void regIsMaleActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
if (regIsMale.isSelected()) {
regIsFemale.setSelected(false);
}
}
private void regIsFemaleActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
if (regIsFemale.isSelected()) {
regIsMale.setSelected(false);
}
}
private void BackButton1ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
Final_2_ClientLogin newClientLoginForm = new Final_2_ClientLogin();
newClientLoginForm.setVisible(true);
newClientLoginForm.pack();
newClientLoginForm.setLocationRelativeTo(null);
this.dispose();
}
private void ClearButton1ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
clearFields();
}
private void NextButton1ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
id = regID.getText();
fullName = regFullName.getText();
birthDate = regBirthDate.getDate();
contactNumber = regContactNumber.getText();
email = regEmail.getText();
district = (String) regDistrict.getSelectedItem();
postalCode = regPostalCode.getText();
if (regIsMale.isSelected()) {
gender = "Male";
} else {
gender = "Female";
}
if (verifyFields()) {
setBankAccPanelValues();
switchToBankAccountPanel();
} else {
JOptionPane.showMessageDialog(null, "One or More Fields are Empty");
}
}
private void NextButton2ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
switchToOnlineAccountPanel();
this.accType = (String) regAccountType.getSelectedItem();
}
private void BackButton2ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
switchToPersonalInfoPanel();
}
private void regAccountTypeItemStateChanged(java.awt.event.ItemEvent evt) {
// TODO add your handling code here:
if (regAccountType.getSelectedIndex() == 0) {
regFixedDepositPeriod.setEnabled(false);
} else {
regFixedDepositPeriod.setEnabled(true);
}
}
private void CreateAccountButtonActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
if (verifyUsernameandPassword()&& !checkUsername()) {
getClientInfo();
System.out.println("true");
PreparedStatement ps;
ResultSet rs;
String registerUserQuery = "INSERT INTO `users`(`national_id`, `full_name`, `birth_date`, `contact_number`, `email`, `gender`, `district`, `postal_code`, `username`, `password`) VALUES (?,?,?,?,?,?,?,?,?,?)";
try {
ps = conn.prepareStatement(registerUserQuery);
ps.setString(1, id);
ps.setString(2, fullName);
ps.setDate(3, (java.sql.Date) birthDate);
ps.setString(4, contactNumber);
ps.setString(5, email);
ps.setString(6, gender);
ps.setString(7, district);
ps.setString(8, postalCode);
ps.setString(9, userName);
ps.setString(10, password);
} catch (SQLException ex) {
Logger.getLogger(Final_3_ClientAccountCreation.class.getName()).log(Level.SEVERE, null, ex);
}
} else {
System.out.println("false");
}
}
private void BackToLoginButtonActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
Final_2_ClientLogin newClientLoginForm = new Final_2_ClientLogin();
newClientLoginForm.setVisible(true);
newClientLoginForm.pack();
newClientLoginForm.setLocationRelativeTo(null);
this.dispose();
}
private void ExitButtonActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
System.exit(0);
}
and the error I get:
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at finalproject.Final_3_ClientAccountCreation.checkUsername(Final_3_ClientAccountCreation.java:143)
at finalproject.Final_3_ClientAccountCreation.CreateAccountButtonActionPerformed(Final_3_ClientAccountCreation.java:779)
at finalproject.Final_3_ClientAccountCreation$9.actionPerformed(Final_3_ClientAccountCreation.java:617)
at java.desktop/javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1967)
at java.desktop/javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2308)
at java.desktop/javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:405)
at java.desktop/javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:262)
at java.desktop/javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:279)
at java.desktop/java.awt.Component.processMouseEvent(Component.java:6635)
at java.desktop/javax.swing.JComponent.processMouseEvent(JComponent.java:3342)
at java.desktop/java.awt.Component.processEvent(Component.java:6400)
at java.desktop/java.awt.Container.processEvent(Container.java:2263)
at java.desktop/java.awt.Component.dispatchEventImpl(Component.java:5011)
at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2321)
at java.desktop/java.awt.Component.dispatchEvent(Component.java:4843)
at java.desktop/java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4918)
at java.desktop/java.awt.LightweightDispatcher.processMouseEvent(Container.java:4547)
at java.desktop/java.awt.LightweightDispatcher.dispatchEvent(Container.java:4488)
at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2307)
at java.desktop/java.awt.Window.dispatchEventImpl(Window.java:2772)
at java.desktop/java.awt.Component.dispatchEvent(Component.java:4843)
at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:772)
at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:721)
at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:715)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85)
at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:95)
at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:745)
at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:743)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85)
at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:742)
at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203)
at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124)
at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113)
at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109)
at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)
The error indicates that the null pointer exception is at line 143, which is in checkUsername function:
public boolean checkUsername() {
PreparedStatement st;
ResultSet rs;
boolean usernameDoesNotExist = true;
System.out.println("Hello");
try {
userName = regUserName.getText();
String query = ("SELECT * FROM `users` WHERE `username` = " + userName);
st = conn.prepareStatement(query); //this is line 143
System.out.println("Hi");
//st.setString(1, userName);
rs = st.executeQuery();
if (rs.next()) {
usernameDoesNotExist = false;
JOptionPane.showMessageDialog(null, "This Username is Already Taken, Choose Another One", "Username Failed", 2);
}
} catch (SQLException ex) {
Logger.getLogger(NewUserForm.class.getName()).log(Level.SEVERE, null, ex);
}
System.out.println(usernameDoesNotExist);
return usernameDoesNotExist;
}
Thank you
