osm.java

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Context ctx = getApplicationContext();
        Configuration.getInstance().load(ctx, PreferenceManager.getDefaultSharedPreferences(ctx));
        setContentView(R.layout.activity_main);

        map = findViewById(R.id.map);
        map.setTileSource(TileSourceFactory.MAPNIK);
        map.setMaxZoomLevel(20);

        map.setMultiTouchControls(true);
        map.setBuiltInZoomControls(true);

        controller = map.getController();
        controller.setZoom(18);
	
	...
}