user: Question: Name the state class for Isaac D. Barnard (J)
Columns: ['State (class)', 'Vacator', 'Reason for change', 'Successor', 'Date of successors formal installation']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Indiana (1)', 'Vacant', 'James Noble died in previous Congress', 'Robert Hanna (AJ)', 'Installed August 19, 1831']
SQL:

assistant: SELECT "State (class)" FROM "Table" WHERE "Vacator" = 'Isaac D. Barnard (J)';