Mapsforge - Vector map library written in Java - running on Android and Desktop.

Mapsforge project uses a compact file format for fast ad-hoc rendering of OpenStreetMap data. It provides tools to compile your own maps with detailed instructions and also precompiled maps, Simple boilerplate code to build applications for Android that display OpenStreetMap-based maps. Mapsforge maps can be flexibly styled with XML style files (render themes).