EPSG 4326 , EPSG 3857 converter

Projection.java

    private static double EARTH_RADIUS = 6378137.0;

    public static LatLng to4326(Wgs84 wgs84) {
        double lat = Math.toDegrees(Math.atan(Math.exp(wgs84.getY() / EARTH_RADIUS)) * 2 - Math.PI/2);
        double lng = Math.toDegrees(wgs84.getX() / EARTH_RADIUS);
        return new LatLng(lat, lng);
    }

    public static Wgs84 toWgs84(LatLng latLng) {
        double x = Math.toRadians(latLng.longitude) * EARTH_RADIUS;
        double y = Math.log(Math.tan(Math.PI / 4 + Math.toRadians(latLng.latitude) / 2)) * EARTH_RADIUS;
        return new Wgs84(x, y);
    }