JTable How to refresh table model after insert delete or update the data.

This is my jTable

private JTable getJTable() {
    String[] colName = { "Name", "Email", "Contact No. 1", "Contact No. 2",
            "Group", "" };
    if (jTable == null) {
        jTable = new JTable() {
            public boolean isCellEditable(int nRow, int nCol) {
                return false;
            }
        };
    }
    DefaultTableModel contactTableModel = (DefaultTableModel) jTable
            .getModel();
    contactTableModel.setColumnIdentifiers(colName);
    jTable.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
    return jTable;
}

I will call this method to retrieve the data from database and put it into table model

public void setUpTableData() {
    DefaultTableModel tableModel = (DefaultTableModel) jTable.getModel();
    ArrayList<Contact> list = new ArrayList<Contact>();
    if (!con.equals(""))
        list = sql.getContactListsByGroup(con);
    else
        list = sql.getContactLists();
    for (int i = 0; i < list.size(); i++) {
        String[] data = new String[7];

            data[0] = list.get(i).getName();
            data[1] = list.get(i).getEmail();
            data[2] = list.get(i).getPhone1();
            data[3] = list.get(i).getPhone2();
            data[4] = list.get(i).getGroup();
            data[5] = list.get(i).getId();

        tableModel.addRow(data);
    }
    jTable.setModel(tableModel);
}

Currently I was using this method to refresh the table after updating the table data. I will first clear the table

DefaultTableModel tableModel = (DefaultTableModel) jTable.getModel();
tableModel.setRowCount(0);

and then restructure the table model again so it will refresh the jTable. But I was thinking is there any best practices or better way to do that?

If you want to notify your JTable about changes of your data, use
tableModel.fireTableDataChanged()

From the documentation:

Notifies all listeners that all cell values in the table's rows may have changed. The number of rows may also have changed and the JTable should redraw the table from scratch. The structure of the table (as in the order of the columns) is assumed to be the same.

The faster way for your case is:

    jTable.repaint(); // Repaint all the component (all Cells).

The optimized way when one or few cell change:

    ((AbstractTableModel) jTable.getModel()).fireTableCellUpdated(x, 0); // Repaint one cell.

try this

public void setUpTableData() {
    DefaultTableModel tableModel = (DefaultTableModel) jTable.getModel();

    /**
    * additional code.
    **/
    tableModel.setRowCount(0);
    /**/
    ArrayList<Contact> list = new ArrayList<Contact>();
    if (!con.equals(""))
        list = sql.getContactListsByGroup(con);
    else
        list = sql.getContactLists();
    for (int i = 0; i < list.size(); i++) {
        String[] data = new String[7];

        data[0] = list.get(i).getName();
        data[1] = list.get(i).getEmail();
        data[2] = list.get(i).getPhone1();
        data[3] = list.get(i).getPhone2();
        data[4] = list.get(i).getGroup();
        data[5] = list.get(i).getId();

        tableModel.addRow(data);
    }
    jTable.setModel(tableModel);
    /**
    * additional code.
    **/
    tableModel.fireTableDataChanged();
    /**/
}

DefaultTableModel dm = (DefaultTableModel)table.getModel();
dm.fireTableDataChanged(); // notifies the JTable that the model has changed