protected short groupColumns(String value,
    String previous,
    String next,
    int currentGroup) 
{
        short groupingKey = GROUP_NO_CHANGE;
        if (lowestEndedGroup <  currentGroup)
        {
            // if a lower group has ended, cascade so that all subgroups end as well
            groupingKey += GROUP_END;
        }
        else if (next == null || !ObjectUtils.equals(value, next))
        {
            // at the end of the list
            groupingKey += GROUP_END;
            lowestEndedGroup = currentGroup;
        }
        if (lowestStartedGroup <  currentGroup)
        {
            // if a lower group has started, cascade so that all subgroups restart as well
            groupingKey += GROUP_START;
        }
        else if (previous == null || !ObjectUtils.equals(value, previous))
        {
            // At the start of the list
            groupingKey += GROUP_START;
            lowestStartedGroup = currentGroup;
        }
        return groupingKey;
}

This takes a column value and grouping index as the argument. It then groups the column and returns the appropriate string back to the caller.

 abstract protected  void writeBottomBanner(TableModel model) throws Exception
Called by writeTable to write the table's footer.

 abstract protected  void writeCaption(TableModel model) throws Exception
Called by writeTable to write the table's caption.

 abstract protected  void writeColumnCloser(Column column) throws Exception
Called by writeTableBody to write the end of the column structure.

 abstract protected  void writeColumnOpener(Column column) throws Exception
Called by writeTableBody to write the start of the column structure.

 abstract protected  void writeColumnValue(Object value,
    Column column) throws Exception
Called by writeTableBody to write a column's value.

 abstract protected  void writeDecoratedRowFinish(TableModel model) throws Exception
Called by writeTableBody to decorate the table.

 abstract protected  void writeDecoratedRowStart(TableModel model) throws Exception
Called by writeTableBody to write to decorate the table.

 abstract protected  void writeDecoratedTableFinish(TableModel model) throws Exception
Called by writeTable to decorate the table.

 abstract protected  void writeEmptyListMessage(String emptyListMessage) throws Exception
Called by writeTable to write a message explaining that the table model contains no data.

 abstract protected  void writeEmptyListRowMessage(String message) throws Exception
Called by writeTableBody to write a message explaining that the row contains no data.

 abstract protected  void writePostBodyFooter(TableModel model) throws Exception
Called by writeTable to write table footer after table body.

 abstract protected  void writePreBodyFooter(TableModel model) throws Exception
Called by writeTable to write table footer before table body.

 abstract protected  void writeRowCloser(Row row) throws Exception
Called by writeTableBody to write the end of the row structure.

 abstract protected  void writeRowOpener(Row row) throws Exception
Called by writeTableBody to write the start of the row structure.

 abstract protected  void writeRowWithNoColumns(String value) throws Exception
Called by writeTableBody to write a row that has no columns.

 public  void writeTable(TableModel model,
    String id) throws JspException 
{
                                                                                              
        try
        {
            // table id used for logging
            this.id = id;
            TableProperties properties = model.getProperties();
            if (log.isDebugEnabled())
            {
                log.debug("[" + this.id + "] writeTable called for table [" + this.id + "]");
            }
            // Handle empty table
            boolean noItems = model.getRowListPage().size() == 0;
            if (noItems && !properties.getEmptyListShowTable())
            {
                writeEmptyListMessage(properties.getEmptyListMessage());
                return;
            }
            // Put the page stuff there if it needs to be there...
            if (properties.getAddPagingBannerTop())
            {
                // search result and navigation bar
                writeTopBanner(model);
            }
            // open table
            writeTableOpener(model);
            // render caption
            if (model.getCaption() != null)
            {
                writeCaption(model);
            }
            // render headers
            if (model.getProperties().getShowHeader())
            {
                writeTableHeader(model);
            }
            // render footer prior to body
            if (model.getFooter() != null)
            {
                writePreBodyFooter(model);
            }
            // open table body
            writeTableBodyOpener(model);
            // render table body
            writeTableBody(model);
            // close table body
            writeTableBodyCloser(model);
            // render footer after body
            if (model.getFooter() != null)
            {
                writePostBodyFooter(model);
            }
            // close table
            writeTableCloser(model);
            if (model.getTableDecorator() != null)
            {
                writeDecoratedTableFinish(model);
            }
            writeBottomBanner(model);
            if (log.isDebugEnabled())
            {
                log.debug("[" + this.id + "] writeTable end");
            }
        }
        catch (Exception e)
        {
            throw new JspException(e);
        }
}

Given a table model, this method creates a table, sorting and grouping it per its configuration, while delegating where and how it writes the table to subclass objects. (Background: This method refactors TableTagData.writeHTMLData method. See above.)

 abstract protected  void writeTableBodyCloser(TableModel model) throws Exception
Called by writeTable to write the end of the table's body.

 abstract protected  void writeTableBodyOpener(TableModel model) throws Exception
Called by writeTable to write the start of the table's body.

 abstract protected  void writeTableCloser(TableModel model) throws Exception
Called by writeTable to write the end of the table's structure.

 abstract protected  void writeTableHeader(TableModel model) throws Exception
Called by writeTable to write the table's header columns.

 abstract protected  void writeTableOpener(TableModel model) throws Exception
Called by writeTable to write the start of the table structure.

 abstract protected  void writeTopBanner(TableModel model) throws Exception
Called by writeTable to write a summary of the search result this table reports and the table's pagination
interface.