change default component in controller in joomla

Question

I am creating a component for joomla. I have a controller like this

class dropdownControllerdropdown extends JControllerForm
{
}

the above controller called by this class

JToolBarHelper::addNew('dropdown.add');

after the controller called that load the dropdown component.otherwise by default the above controller call this component and view and layout .

index.php?option=com_dropdown&view=dropdown&layout=edit

but my component name is "test" .how I tell to the controller to do not load the "dropdown" component and load the "test" component?