import javax.swing.JTable;
import javax.swing.table.DefaultTableModel;
import javax.swing.table.TableColumn;
public class Main {
public static void main(String[] argv) throws Exception {
DefaultTableModel model = new DefaultTableModel();
JTable table = new JTable(model);
model = (DefaultTableModel) table.getModel();
TableColumn col = new TableColumn(model.getColumnCount());
// Ensure that auto-create is off
if (table.getAutoCreateColumnsFromModel()) {
throw new IllegalStateException();
}
col.setHeaderValue("Col3");
table.addColumn(col);
model.addColumn("Col3", new Object[] { "v3" });
}
}