A TableAssistant object is created internally by AdvancedJTable. You can get an instance of it by calling AdvancedJTable's method:

public TableAssistant getTableAssistant();

You can also use this class with your own custom JTable:

JTable table = new JTable();

TableAssistant tableAssistant = new TableAssistant(table);

tableAssistant.register(table.getColumnModel());