Try this way
Polygon polygon;
LatLng polLatLng;
PolygonOptions rectOptions=new PolygonOptions();
if(polarl.size()>0){
for(int k=0;k<polarl.size();k++){
String polLat =polarl.get(k).get("polLat").toString();
String polLng =polarl.get(k).get("polLng").toString();
if ( !polLat.trim().equals("") && !polLng.trim().equals("")){
double HPollat = Double.parseDouble(polLat.trim());
double HPolLong= Double.parseDouble(polLng.trim());
polLatLng=new LatLng(HPollat, HPolLong);
Log.e("POL LAT LANG", ""+polLatLng);
rectOptions.add(polLatLng);
}
}
}
Polygon polygon1 = _googleMap.addPolygon(rectOptions.strokeColor(Color.RED).fillColor(Color.BLUE));
For more information go to this SO POST