When you create a map, you must register it with the map manager. Next, you must display it in the UI.

For a GXY map, you can trigger the map creation action that is available in the UI, which will take care of both steps.

ILcyLucyEnv lucy = ...;

//Search for the create map action
//The code below assumes the action is available in the menu bar,
//which is the case for a default Lucy
TLcyActionBarManager actionBarManager = lucy.getUserInterfaceManager().getActionBarManager();
ILcdAction createMapAction = TLcyActionBarUtil.findAction("TLcyMapAddOn.createMapAction",

//If the action is found, trigger it
if(createMapAction != null){
  createMapAction.actionPerformed(new ActionEvent(this, ActionEvent.ACTION_PERFORMED, "Create map"));