public void createProfile(
      String username, String password, String securityQuestion, String securityAnswer) {
    // Create a linked list containing the user's password, security question, and security answer.
    LinkedList<String> userProfile = new LinkedList<>();
    userProfile.add(ProfileItem.USERNAME.ordinal(), username);
    userProfile.add(ProfileItem.PASSWORD.ordinal(), password);
    userProfile.add(ProfileItem.QUESTION.ordinal(), securityQuestion);
    userProfile.add(ProfileItem.ANSWER.ordinal(), securityAnswer);

    // Add the user's profile to the linked list.
    profileList.add(userProfile);
  }
 /**
  * This class is a singleton class. Instances may only be obtained using the getInstance() method.
  */
 private ProfileModel() {
   currentUsername = null;
   profileList = new LinkedList<>();
   if (DEBUG) {
     LinkedList<String> adminAccount = new LinkedList<>();
     adminAccount.add(ProfileItem.USERNAME.ordinal(), "admin");
     adminAccount.add(ProfileItem.PASSWORD.ordinal(), "password");
     adminAccount.add(ProfileItem.QUESTION.ordinal(), null);
     adminAccount.add(ProfileItem.ANSWER.ordinal(), null);
     profileList.add(adminAccount);
   }
 }