To install a TreeTableHeader on a table, the TreeTableColumnModel that will contain the hierarchical column structure must first be created. Since, by assigning the tree header to the table, will make the table assign its 'flat' column model to the header, the TreeTableHeader's column model must be assigned to the table prior to assigning the header to the table. Otherwise, a ClassCastException will be thrown.

Example:

DefaultTreeTableColumnModel model = new DefaultTreeTableColumnModel();

//fill the model with some values as in this example

//create the TreeTableHeader

TreeTableHeader treeHeader = new TreeTableHeader(model);

//create the table

AdvancedJTable table = new AdvancedJTable();

//assign the 'tree' column model of the tree header - THIS IS IMPORTANT

table.setColumnModel(treeHeader.getColumnModel());

//assign the tree header to the table

table.setTableHeader(treeHeader);