DefaultSpanModel fires a SpanModelEvent every time a cell span is added or removed. You can listen for SpanModelEvents by creating a class that implements SpanModelListener and adding it to the SpanModel's SpanModelListeners list. For example, SpanDrawer contains an internal SpanModelListener that repaints the table's area that was affected by a cell span being added/removed.

Example: Create a SpanModelListener.

SpanModelListenerer mySpanModelListener = new SpanModelListener() {

       public void spanChanged(SpanModelEvent e) {

               int type = e.getType();

               CellSpan cs = e.getCellSpan();

               if (type = e.INSERT) {

                       …

               }

               if (type = e. DELETE) {

                       …

               }

               if (type = e. UPDATE) {

                       …

               }

       }

};

SpanDrawer drawer = table.getSpanDrawer();

SpanModel spanModel = drawer.getSpanModel();

spanModel.addSpanModelListener(mySpanModelListener);