java code to convet to CSV

public static StringBuffer convert(JTable table) {
    StringBuffer sbf = new StringBuffer();
    // Check to ensure we have selected only a contiguous block of cells
    int numcols = table.getColumnCount();
    int numrows = table.getSelectedRowCount();
    int[] rowsselected = table.getSelectedRows();

    if (numrows <= 0) {
        JOptionPane.showMessageDialog(null, "Invalid Copy Selection. Please select atleast one Row.", "Error",
                                      JOptionPane.ERROR_MESSAGE);
        return null;
    }
    for (int i = 0; i < numcols; i++) {
        sbf.append(table.getColumnName(i));
        if (i < numcols - 1) {
            sbf.append(",");
        }
    }
    sbf.append("\n");

    for (int i = 0; i < numrows; i++) {
        for (int j = 0; j < numcols; j++) {
            Object obj = table.getValueAt(rowsselected[i], j);
            if (obj instanceof String) {
                sbf.append("\"");
                sbf.append(obj);
                sbf.append("\"");
            } else if (obj instanceof XDouble) {
                sbf.append("\"");
                sbf.append(table.getValueAt(rowsselected[i], j));
                sbf.append("\"");
            } else if (obj instanceof java.sql.Timestamp) {
                XDate wdt = new XDate((java.sql.Timestamp)
                                      obj);
                sbf.append(wdt);
            } else {
                sbf.append(table.getValueAt(rowsselected[i], j));
            }
            if (j < numcols - 1) {
                sbf.append(",");
            }
        }
        sbf.append("\n");
    }
    return sbf;
}