private static ArrayList<Student> registeredUsers = new ArrayList<Student>(); // ArrayList to store Student objects
    public static StudentManager sm;

    public Register() {
    initComponents();
    Initialization();
    }

    static void Initialization(){

    sm = new StudentManager();

    try {
        // Reads the objects from the .txt file
        registeredUsers = sm.load();
               } catch(Exception ex) {
               ex.printStackTrace();
               }
    }

// Registering a new Student to the system
    private void RegisterNewButtonActionPerformed(java.awt.event.ActionEvent evt) {
    boolean valid_studentID = false;
    boolean valid_firstName = false;
    boolean valid_lastName = false;
    boolean valid_contactNo = false;
    boolean valid_email = false;
    boolean valid_carNo = false;

       // Test if 'StudentID' field is empty
       if(StudentIDBox.getText().isEmpty()){
       JFrame frame = new JFrame("");
       JOptionPane.showMessageDialog(frame, "StudentID field is empty.", "TODO", JOptionPane.OK_OPTION);

       // Test if studentID already exists
       }else if(!StudentIDBox.getText().isEmpty()){
           String testStudentID = StudentIDBox.getText();
          // Search  existing Students for a possible match
           if(sm.searchStudents(registeredUsers, testStudentID) == true){
           JFrame frame = new JFrame("");
           JOptionPane.showMessageDialog(frame, "StudentID already exists.", "TODO", JOptionPane.OK_OPTION);
           }
           // If StudentID is valid
           if(sm.searchStudents(registeredUsers, testStudentID) == false){
           studentID = StudentIDBox.getText();
           valid_studentID = true;
           }

       // Continue and check if 'First name' is valid
       if(valid_studentID){

           // Test if 'First name' field is empty
           if(FirstNameBox.getText().isEmpty()){
           JFrame frame = new JFrame("");
           JOptionPane.showMessageDialog(frame, "First name field is empty.", "TODO", JOptionPane.OK_OPTION);
           // If not empty, assign to a variable
           }else if(!FirstNameBox.getText().isEmpty()){
           firstName = FirstNameBox.getText();
           valid_firstName = true;
           }
       }

       // Continue and check if 'Last name' is valid
       if(valid_firstName){

           // Test if 'Last name' field is empty
           if(LastNameBox.getText().isEmpty()){
           JFrame frame = new JFrame("");
           JOptionPane.showMessageDialog(frame, "Last name field is empty.", "TODO", JOptionPane.OK_OPTION);
           }else if(!LastNameBox.getText().isEmpty()){
           lastName = LastNameBox.getText();
           valid_lastName = true;
           }
       }

       // Continue and check if 'Contact number' is valid
       if(valid_lastName){

           if(ContactNoBox.getText().isEmpty()){
           JFrame frame = new JFrame("");
           JOptionPane.showMessageDialog(frame, "Contact number field is empty.", "TODO", JOptionPane.OK_OPTION);
           }else if(!ContactNoBox.getText().isEmpty()){
           if(ContactNoBox.getText().matches("[0-9]+")){
           // Save contact number and convert it to Integer
           contactNumber = ContactNoBox.getText();
           valid_contactNo = true;
           }else{
               JFrame frame = new JFrame("");
               JOptionPane.showMessageDialog(frame, "Contact number field contains invalid characters.", "TODO", JOptionPane.OK_OPTION);
           }
           }
       }

       // Continue and check if 'Email address' is valid
       if(valid_contactNo){
           if(EmailBox.getText().isEmpty()){
           JFrame frame = new JFrame("");
           JOptionPane.showMessageDialog(frame, "Email address field is empty.", "TODO", JOptionPane.OK_OPTION);
           }else if(!EmailBox.getText().isEmpty()){
           // Save Email address
           emailAddress = EmailBox.getText();
           valid_email = true;
           }
       }

       // Continue and check if 'Car Number' is valid
       if(valid_email){
           if(CarNoBox.getText().isEmpty()){
           JFrame frame = new JFrame("");
           JOptionPane.showMessageDialog(frame, "Car number field is empty.", "TODO", JOptionPane.OK_OPTION);
           }else if(!CarNoBox.getText().isEmpty()){
           // Save Car number
           carNumber = CarNoBox.getText();
           valid_carNo = true;
           }
       }

       // If all the information is OK, register user to the system
       if (valid_studentID && valid_firstName && valid_lastName && valid_contactNo && valid_email && valid_carNo){
        currentDate = new SimpleDateFormat("dd-MM-yyyy HH:mm").format(new Date());
        System.out.println(currentDate);
        registeredUsers.add(new Student(studentID, firstName, lastName, contactNumber, emailAddress, carNumber, currentDate));
        JFrame frame = new JFrame("");
        JOptionPane.showMessageDialog(frame, "StudentID: "+studentID+" was registered to the system.", "Registration successful.", JOptionPane.INFORMATION_MESSAGE);
        System.out.println("Debug log: New student registered");
        System.out.println("Debug log: Number of registered students = "+registeredUsers.size());
          try {
              // Save the user to the system
               sm.save(registeredUsers);
               } catch(Exception ex) {
               ex.printStackTrace();
               }
             }
    }
    }