JTable using abstracttablemodel not updating after insert

Question

This is a follow-up question to my post here.

My JTable is populated using abstracttablemodel. I implemented an insertRow method which works perfectly in the database but does not refresh my JTable. As seen in the code below, after the insert, I use the fireTableRowsInserted method to update the model but this doesn't seem to work. The abstracttablemodel with insertRow method is as below:

class ResultSetTableModel extends AbstractTableModel
{
 private final Connection connection;
 private final Statement statement;
 private ResultSet resultSet;
 private ResultSetMetaData resultSetMetaData;
 private int numberOfRows;
 
 private static final String oracleDriver = "oracle.jdbc.driver.OracleDriver";


 //track DB connection status
 private boolean dbConnStatus = false;
 
 //constructor initializes rSet and obtains its
 //metadata object; also determines number of rows
 public ResultSetTableModel(String oracleConnection, String username, String password, String query) throws SQLException
 {
  
  //connect to the database
  connection = getDBConnection(oracleConnection, username, password);
  
  //create statement to query database
  statement = connection.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_UPDATABLE);
  
  //update database connection status
  dbConnStatus = true;
  
  //set query and execute it
  setQuery(query);
 }
 
 private static Connection getDBConnection(String oraConn, String user, String pwd)
 {
  Connection dbConn = null;
  
  try
  {
   Class.forName(oracleDriver);
  }
  catch (ClassNotFoundException classExcep)
  {
   System.out.println(classExcep.getMessage());
  }
  
  try
  {
   dbConn = DriverManager.getConnection(oraConn, user, pwd);
   
   return dbConn;
  }
  catch (SQLException sqlExcep)
  {
   System.out.println(sqlExcep.getMessage());
  }
  
  return dbConn;
 }
 
 //get class that represents column type
 @SuppressWarnings({ "unchecked", "rawtypes" })
 public Class getColumnClass(int column) throws IllegalStateException
 {
  //ensure database connection is available
  if(!dbConnStatus)
   throw new IllegalStateException("No connection to the Database");
  
  //determine Java class of column
  try
  {
   String className = resultSetMetaData.getColumnClassName(column + 1);
   
   //return Class object that represents class Name
   return Class.forName(className);
  }
  catch (Exception e)
  {
   e.printStackTrace();
  }
  
  return Object.class; //if problems occur above, assume type Object
 }

 //remove row in the ResultSet
 public void removeRow(String empID)
 {
  int rsRow = 0;
  
  try
  {
   //set cursor to beginning of data set (before first row)
   if(!resultSet.isBeforeFirst())
    resultSet.beforeFirst();
   
   //iterate through resultSet to find matching record with
   //correct employee ID. once found delete row
   while(resultSet.next())
   {
    if(resultSet.getString("EMPLOYEENO").equals(empID))
    {
     rsRow = resultSet.getRow();
     
     resultSet.absolute(rsRow);
     resultSet.deleteRow();
     
     break;
    }
   }
 
   resultSet.last();
   numberOfRows = resultSet.getRow();

   fireTableDataChanged();

  }
  catch (SQLException e)
  {
   e.printStackTrace();
  }
 }
 
 //add row into ResultSet
 public void insertRow(String fName, String lName, String userID, String company, String group)
 {
  //get display name of user
  String displayName = fName.substring(0, 1).concat(". ").concat(lName);

  try
  {
   //move cursor to staging row for record insertion
   resultSet.moveToInsertRow();
   
   resultSet.updateString("EMPLOYEENO", userID);
   resultSet.updateString("FIRSTNAME", fName);
   resultSet.updateString("LASTNAME", lName);
   resultSet.updateString("DISPLAYNAME", displayName);
   resultSet.updateString("GROUPNAME", group);
   resultSet.updateString("COMPANYNAME", company);
   
   resultSet.insertRow();
   resultSet.beforeFirst();
   
   //resultSet.last();
   //row = resultSet.getRow();

   //fireTableDataChanged();
   //fireTableStructureChanged();
   fireTableRowsInserted(this.getRowCount() - 1, this.getRowCount() - 1);

  } 
  catch (SQLException e)
  {
   e.printStackTrace();
  } 
 }
 
 //get the number of columns in the ResultSet
 public int getColumnCount() throws IllegalStateException
 {
  //ensure database connection is available
  if(!dbConnStatus)
   throw new IllegalStateException("No connection to the Database");
  
  //determine number of columns
  try
  {
   return resultSetMetaData.getColumnCount();
  }
  catch (SQLException sqlException)
  {
   sqlException.printStackTrace();
  }
  
  return 0; //if problem occur above, return 0 for number of columns
 }
 
 //get name of a particular column in ResultSet
 public String getColumnName(int column) throws IllegalStateException
 {
  //ensure database connection is available
  if(!dbConnStatus)
   throw new IllegalStateException("No connection to the Database");
  
  //determine column name
  try
  {
   return resultSetMetaData.getColumnName(column + 1);
  }
  catch (SQLException sqlException)
  {
   sqlException.printStackTrace();
  }
  
  return ""; //if problems occur above, return empty string for column name 
 }
 
 //return number of rows in ResultSet
 public int getRowCount() throws IllegalStateException
 {
  //ensure database connection is available
  if(!dbConnStatus)
   throw new IllegalStateException("No connection to the Database");
  
  return numberOfRows; 
 }
 
 //obtain value in particular row and column
 public Object getValueAt(int row, int column) throws IllegalStateException
 {
  //ensure database connection is available
  if(!dbConnStatus)
   throw new IllegalStateException("No connection to the Database");
  
  //obtain a value at specified ResultSet row and column
  try
  {
   resultSet.absolute(row + 1);
   return resultSet.getObject(column + 1);
  }
  catch (SQLException sqlException)
  {
   sqlException.printStackTrace();
  }
  
  return ""; //if problems occur above, return empty string object  
 }
 
 //set new database query string
 public void setQuery(String query) throws SQLException, IllegalStateException
 {
  //ensure database connection is available
  if(!dbConnStatus)
   throw new IllegalStateException("No connection to the Database");
  
  //specify query and execute it
  resultSet = statement.executeQuery(query);
  
  //obtain metadata for ResultSet
  resultSetMetaData = resultSet.getMetaData();
  
  //determine number of rows in ResultSet
  resultSet.last(); //move to last row
  numberOfRows = resultSet.getRow(); //get row number
  
  //notify JTable that model has changed
  fireTableStructureChanged();
 }
 
 //close Statement and Connection
 public void disconnectFromDatabase()
 {
  //ensure database connection is available
  if(dbConnStatus);
  
  //determine number of columns
  try
  {
   resultSet.close();
   statement.close();
   connection.close();
  }
  catch (SQLException sqlException)
  {
   sqlException.printStackTrace();
  }
  finally
  {
   dbConnStatus = false;
  }
  
 }
} //end class ResultSetTableModel

My custom JFrame class that includes the button call for the insert:

class AdministrationFrame extends JFrame
{
//set default query to retrieve all non-disabled users
private static final String DEFAULT_QUERY = 
    "SELECT EMPLOYEENO, FIRSTNAME, LASTNAME, DISPLAYNAME, GROUPNAME, COMPANYNAME "
    + "FROM EMPLOYEES "
    + "WHERE DISABLED IS NULL ";

//query to retrieve all groups
private static final String ALL_GROUPS_QUERY = 
    "SELECT DISTINCT GROUPNAME "
    + "FROM EMPLOYEES "
    + "ORDER BY GROUPNAME ";

private static final String ALL_COMPANIES_QUERY = 
    "SELECT DISTINCT COMPANYNAME "
    + "FROM EMPLOYEES ";

private static final String ORACLE_CONNECTION = "jdbc:oracle:thin:@..."; //connection to UAT DB

private static final String USERNAME = "...";
private static final String PASSWORD = "...";

//layout for window
private final BorderLayout layout;

private final GridBagLayout gbLayout;
private final GridBagConstraints c;

//administration window
private final JFrame adminFrame;

private final JPanel tablePanel;
private final JPanel tablePanel2;
private final JPanel modifyPanel;
private final JPanel buttonPanel;

//items for tablePanel
private final JLabel filterLabel;
private final JTextField filterTextField;
private final JButton filterButton;

//items for modifyPanel
private final JLabel firstNameLabel;
private final JLabel lastNameLabel;
private final JLabel userIDLabel;
private final JLabel companyLabel;
private final JLabel groupLabel;

private final JTextField firstNameField;
private final JTextField lastNameField;
private final JTextField userIDField;
private final JTextField companyField;
private final JTextField groupField;

private final JComboBox<String> groupsDropDown;
private final JComboBox<String> companiesDropDown;

//items for buttonPanel
private final JButton updateButton;

private Connection conn;

private JTable resultTable;

private static ResultSetTableModel tblModel;

@SuppressWarnings("unchecked")
public AdministrationFrame()
{
  layout = new BorderLayout(10, 10);
  setLayout(layout);

  gbLayout = new GridBagLayout();
  c = new GridBagConstraints();

  //place GUI components on JFrame's content pane
  adminFrame = new JFrame("Employee Modification Panel");

  //set up JPanels
  tablePanel = new JPanel();
  tablePanel2 = new JPanel();

  String tablePanelTitle = "Employee Details";
  tablePanel.setBorder(BorderFactory.createTitledBorder(null, 
      tablePanelTitle, TitledBorder.CENTER, TitledBorder.TOP,
      new Font("Arial", Font.BOLD + Font.ITALIC, 22), Color.BLACK));

  tablePanel2.setLayout(new BoxLayout(tablePanel2, BoxLayout.Y_AXIS));

  modifyPanel = new JPanel();
  modifyPanel.setLayout(gbLayout);

  buttonPanel = new JPanel();

  //set up items in each JPanel
  filterLabel = new JLabel("Filter:");
  filterLabel.setAlignmentX(LEFT_ALIGNMENT);
  filterTextField = new JTextField();
  filterTextField.setAlignmentX(LEFT_ALIGNMENT);
  filterButton = new JButton("Apply Filter");
  filterButton.setAlignmentX(LEFT_ALIGNMENT);

  firstNameLabel = new JLabel("First Name:");
  lastNameLabel = new JLabel("Last Name:");
  userIDLabel = new JLabel("Employee ID:");
  companyLabel = new JLabel("Company:");
  groupLabel = new JLabel("Group:");

  firstNameField = new JTextField();
  lastNameField = new JTextField();
  userIDField = new JTextField();
  companyField = new JTextField();
  companyField.setEditable(false);
  groupField = new JTextField();
  groupField.setEditable(false);

  updateButton = new JButton("Insert/Modify");

  //create custom renderer for the company & group
  //drop down menus - changes their behavior
  class PromptComboBoxRenderer extends BasicComboBoxRenderer
  {
    //set the text to display when no item has been selected
    private String prompt;

    public PromptComboBoxRenderer(String prompt)
    {
      this.prompt = prompt;
    }

    @SuppressWarnings("rawtypes")
    public Component getListCellRendererComponent(
        JList list, Object value, int index,
        boolean isSelected, boolean cellHasFocus)
    {
      super.getListCellRendererComponent(list, value, index, isSelected, cellHasFocus);

      if(value == null)
        setText(prompt);

      return this;
    }
  }

  groupsDropDown = new JComboBox<String>();
  groupsDropDown.setRenderer(new PromptComboBoxRenderer("Select a Group"));
  groupsDropDown.addItemListener(new ItemListener() //anonymous inner class
  {
    @Override
    public void itemStateChanged(ItemEvent event)
    {
      if(event.getStateChange() == ItemEvent.SELECTED)
      {
        if(groupsDropDown.getSelectedItem().toString() != "")
        {
          String selectedGroup = groupsDropDown.getSelectedItem().toString();
          //System.out.println("You selected group: " + selectedGroup);
          groupField.setText(selectedGroup);
        }
      }
    }
  });

  companiesDropDown = new JComboBox<String>();
  companiesDropDown.setRenderer(new PromptComboBoxRenderer("Select a Company"));
  companiesDropDown.addItemListener(new ItemListener() //anonymous inner class
  {
    @Override
    public void itemStateChanged(ItemEvent event)
    {
      if(event.getStateChange() == ItemEvent.SELECTED)
      {
        if(companiesDropDown.getSelectedItem().toString() != "")
        {
          String selectedCompany = companiesDropDown.getSelectedItem().toString();
          //System.out.println("You selected company: " + selectedCompany);
          companyField.setText(selectedCompany);
        }
      }
    }
  });

  //user click "Insert/Modify"
  updateButton.addActionListener(new ActionListener()
  {
    @Override
    public void actionPerformed(ActionEvent e)
    {
      tblModel.insertRow(getFirstName(), getLastName(), getUserID(), getCompany(), getGroup());
      refreshScreen();

    }
  });

  //create ResultSetTableModel and display database table
  try
  {
    //create TableModel for results of the default query
    tblModel = new ResultSetTableModel(ORACLE_CONNECTION, USERNAME, PASSWORD, DEFAULT_QUERY);

    //create JTable based on the tblModel
    resultTable = new JTable(tblModel)
    {
      @Override
      public Dimension getPreferredScrollableViewportSize()
      {
        return new Dimension(600, 250);
      }
    };

    resultTable.setAutoResizeMode(JTable.AUTO_RESIZE_ALL_COLUMNS);
    resultTable.getTableHeader().setResizingAllowed(false); //disable column resizing
    resultTable.getTableHeader().setReorderingAllowed(false); //disable column dragging
    resultTable.setSelectionMode(ListSelectionModel.SINGLE_SELECTION); //sets table to only allow selection of single row
    resultTable.getSelectionModel().addListSelectionListener(new RowListener()); //register event handlers
    final JScrollPane tablePane = new JScrollPane(resultTable);

    //add items to JPanels
    tablePanel2.add(filterLabel);
    tablePanel2.add(Box.createRigidArea(new Dimension(0, 2)));
    tablePanel2.add(filterTextField);
    tablePanel2.add(Box.createRigidArea(new Dimension(0, 10)));
    tablePanel2.add(filterButton);

    tablePanel.add(tablePane);
    tablePanel.add(tablePanel2);

    buttonPanel.add(updateButton);

    //fill ComboBoxes
    conn = DriverManager.getConnection(ORACLE_CONNECTION, USERNAME, PASSWORD);
    Statement stmt = conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);

    ResultSet groupResultSet = stmt.executeQuery(ALL_GROUPS_QUERY);

    while(groupResultSet.next())
    {
      String group = groupResultSet.getString("GROUPNAME");
      groupsDropDown.addItem(group);
    }

    groupsDropDown.setSelectedIndex(-1);
    groupField.setText("");

    ResultSet companiesResultSet = stmt.executeQuery(ALL_COMPANIES_QUERY);

    while(companiesResultSet.next())
    {
      String company = companiesResultSet.getString("COMPANYNAME");
      companiesDropDown.addItem(company);
    }

    companiesDropDown.setSelectedIndex(-1);
    companyField.setText("");

    //add items to modifyPanel
    c.fill = GridBagConstraints.HORIZONTAL;
    c.insets = new Insets(10, 150, 5, 0); //no padding on right for labels
    c.gridx = 0;
    c.gridy = 0;
    modifyPanel.add(firstNameLabel, c);

    c.gridx = 0;
    c.gridy = 1;
    modifyPanel.add(lastNameLabel, c);

    c.gridx = 0;
    c.gridy = 2;
    modifyPanel.add(userIDLabel, c);

    c.gridx = 0;
    c.gridy = 3;
    modifyPanel.add(companyLabel, c);

    c.gridx = 0;
    c.gridy = 4;
    modifyPanel.add(groupLabel, c);

    c.insets = new Insets(0, 10, 5, 10); //no padding on top for fields
    c.anchor = GridBagConstraints.SOUTH;
    c.fill = GridBagConstraints.BOTH;
    c.weightx = 1;

    c.gridx = 1;
    c.gridy = 0;
    c.gridwidth = 2;
    modifyPanel.add(firstNameField, c);

    c.gridx = 1;
    c.gridy = 1;
    c.gridwidth = 2;
    modifyPanel.add(lastNameField, c);

    c.gridx = 1;
    c.gridy = 2;
    c.gridwidth = 2;
    modifyPanel.add(userIDField, c);

    c.gridx = 1;
    c.gridy = 3;
    c.gridwidth = 2;
    modifyPanel.add(companyField, c);

    c.gridx = 1;
    c.gridy = 4;
    c.gridwidth = 2;
    modifyPanel.add(groupField, c);

    c.insets = new Insets(0, 10, 5, 80); //padding for dropdowns
    c.gridx = 4;
    c.gridy = 3;
    modifyPanel.add(companiesDropDown, c);

    c.gridx = 4;
    c.gridy = 4;
    modifyPanel.add(groupsDropDown, c);

    //add JPanels to frame
    adminFrame.add(tablePanel, BorderLayout.NORTH);
    adminFrame.add(modifyPanel, BorderLayout.CENTER);
    adminFrame.add(buttonPanel, BorderLayout.SOUTH);   

    final TableRowSorter<TableModel> sorter = new TableRowSorter<TableModel>(tblModel);
    resultTable.setRowSorter(sorter);

    //create listener for filterButton
    filterButton.addActionListener(new ActionListener()
    {
      //pass filter text to Listener
      public void actionPerformed(ActionEvent e)
      {
        String text = filterTextField.getText();

        if (text.length() == 0)
          sorter.setRowFilter(null);
        else
        {
          try
          {
            //make filter case-insensitive
            sorter.setRowFilter(RowFilter.regexFilter("(?i)" + text));
          }
          catch (PatternSyntaxException pse)
          {
            JOptionPane.showMessageDialog(null, "Bad regex pattern",
                "Bad regex pattern", JOptionPane.ERROR_MESSAGE);
          }
        }
      }
    });

    pack();

    //dispose of window when user quits application
    //(do not want to close application)
    adminFrame.setDefaultCloseOperation(DISPOSE_ON_CLOSE);
    adminFrame.setSize(800, 600);
    adminFrame.setVisible(true);
    adminFrame.setLocationRelativeTo(null);
    adminFrame.setResizable(false);

    //ensure database is closed when user quits application
    adminFrame.addWindowListener(new WindowAdapter()
    {
      //disconnect from database and exit when window has closed
      public void windowClosed(WindowEvent event)
      {
        tblModel.disconnectFromDatabase();
        System.exit(0);
      }
    });
  }
  catch (SQLException sqlException)
  {
    JOptionPane.showMessageDialog(null, sqlException.getMessage(),
        "Database error", JOptionPane.ERROR_MESSAGE);
    tblModel.disconnectFromDatabase();
    System.exit(1); //terminate application
  }
}

private class RowListener implements ListSelectionListener
{
  @Override
  public void valueChanged(ListSelectionEvent event)
  {
    if(!event.getValueIsAdjusting())
    {
      int row = resultTable.getSelectedRow();
      if(row == -1) //no row found
        JOptionPane.showMessageDialog(adminFrame, "Selected row not found in filtered set",
            null, JOptionPane.WARNING_MESSAGE);
      else
      {
        firstNameField.setText(resultTable.getValueAt(row, resultTable.getColumn("FIRSTNAME").getModelIndex()).toString());
        lastNameField.setText(resultTable.getValueAt(row, resultTable.getColumn("LASTNAME").getModelIndex()).toString());
        userIDField.setText(resultTable.getValueAt(row, resultTable.getColumn("EMPLOYEENO").getModelIndex()).toString());
        companyField.setText(resultTable.getValueAt(row, resultTable.getColumn("COMPANYNAME").getModelIndex()).toString());
        groupField.setText(resultTable.getValueAt(row, resultTable.getColumn("GROUPNAME").getModelIndex()).toString());
      }
    }
  }
};

//refreshes the window after an update
//by clearing out all fields
//and resetting dropdown menus
public void refreshScreen()
{
  firstNameField.setText("");
  lastNameField.setText("");
  userIDField.setText("");
  companyField.setText("");
  groupField.setText("");

  groupsDropDown.setSelectedIndex(-1);
  companiesDropDown.setSelectedIndex(-1);

}

//get methods for text fields
public String getFirstName()
{
  return firstNameField.getText();
}

public String getLastName()
{
  return lastNameField.getText();
}

public String getUserID()
{
  return userIDField.getText();
}

public String getCompany()
{
  return companyField.getText();
}

public String getGroup()
{
  return groupField.getText();
}

}//end class EmpInOutBoard

I noticed other similar posts using abstracttablemodel have used Lists or some other type of collection to modify the underlying result set. Is this something I need with my application as well or am I missing something very basic here?

Thank in advance.