Following this guide (https://code.google.com/p/mapsforge/wiki/GettingStartedMapWriter#Examples), I can create now maps in format .map to be used with android mapsforge libraries.
The question is: is possible to create custom maps with osmosis and mapsforge map-writer in terms of selected objects? I mean, is possible to create maps that not include the buildings, for example? Thanks in advance.
Yes, osmosis can filter for tags. You can accept or reject specific tags as well as specific elements. See example usage in the OSM wiki as well as the detailed usage instructions.