How to sort various data types in one column in NatTables

I do have all values in Nattable as strings. I used IConfigLabelAccumulator and added labels DataTypeStringLabel = "String" and DataTypeNumberLabel = "Number" to cells. In one column can be values with both types of labels:

  public BodyLayerStack(List<TableLine> values, int columnCount, Integer[] columnIndicesForRowHeaders)
  {
    EventList<TableLine> eventList = GlazedLists.eventList(values);
    TransformedList<TableLine, TableLine> rowObjectsGlazedList = GlazedLists.threadSafeList(eventList);

    // this.filterList = new FilterList<>(rowObjectsGlazedList); //changed to:
    // use the SortedList constructor with 'null' for the Comparator
    // because the Comparator will be set by configuration
    sortedList = new SortedList<>(rowObjectsGlazedList, null);
    // wrap the SortedList with the FilterList
    filterList = new FilterList<>(sortedList);
    
    bodyDataProvider = new ListDataProvider<TableLine>(filterList, getColumnAccessor(columnCount));
    bodyDataLayer = new DataLayer(bodyDataProvider);

    IConfigLabelAccumulator cellLabelAccumulator = new IConfigLabelAccumulator() {
      
      @Override
      public void accumulateConfigLabels(LabelStack configLabels, int columnPosition, int rowPosition) {
        int columnIndex = bodyDataLayer.getColumnIndexByPosition(columnPosition);
        int rowIndex = bodyDataLayer.getRowIndexByPosition(rowPosition);
        if( isRowHeader(columnIndicesForRowHeaders, columnIndex) ) {
          configLabels.addLabel(NatTableFactory.RowHeaderLabel);
        } else {
          // get dataTypes at actual positions and add/refresh labels 
          configLabels.addLabel(filterList.get(rowIndex).getObjectTypeByColumn(columnIndex));
          if(configLabels.getLabels().get(0) != null && configLabels.getLabels().get(0)=="Number") {
            System.out.println("Number");                
          }
        }
      }
    };
    bodyDataLayer.setConfigLabelAccumulator(cellLabelAccumulator);
    
    GlazedListsEventLayer<TableLine> glazedListsEventLayer = new GlazedListsEventLayer<>(bodyDataLayer, filterList);
    
    selectionLayer = new SelectionLayer(glazedListsEventLayer, false);
    selectionLayer.setSelectionModel(getSelectionModel());
    selectionLayer.addConfiguration(getSelectionConfiguration());
    
    setUnderlyingLayer(new ViewportLayer(selectionLayer));
  }

For now, all values are sorted as strings (as expected). But I need to sort values with label Number as numbers.

What would be better: convert data to numbers, or use custom comparator?

• If I use data conversion, data are converted only for sort purpose? I need to keep data as Strings after sorting.
• If I use custom comparator, I am not sure, how to register Labels. Should I use already created IConfigLabelAccumulator cellLabelAccumulator?

I was trying:

  public static IConfiguration getCustomComparatorConfiguration(final AbstractLayer columnHeaderDataLayer) {
    return new AbstractRegistryConfiguration() {

      @Override
      public void configureRegistry(IConfigRegistry configRegistry) {
        
        // Register labels
        BodyLayerStack.super.getConfigLabelAccumulator().registerOverride( //ERROR
            4, //here should come index of sorted column?
                NatTableFactory.DataTypeNumberLabel);

        // Register custom comparator
        configRegistry.registerConfigAttribute(
                SortConfigAttributes.SORT_COMPARATOR,
                NatTableLayerConfigurations.getCustomComparator(),
                DisplayMode.NORMAL,
                NatTableFactory.DataTypeNumberLabel);
      }
    };
  }

but I get The method registerOverride(int, String) is undefined for the type IConfigLabelAccumulator.

You get an IConfigLabelAccumulator which does not provide the registerOverride(int, String) method. Not sure which subclass defines that method. The ColumnOverrideLabelAccumulator provides the method registerColumnOverride(int, String)

I would suggest to use a custom Comparator if the sorting based on String representations is not sufficient.

https://www.eclipse.org/nattable/documentation.php?page=sorting