gistfile1.java

import com.google.android.gms.maps.model.LatLng;
import com.google.common.collect.Lists;
import java.util.List;

import static java.lang.Math.*;

public class CircleMaker {
    private static final double EARTH_RADIUS = 6371000.0; /* meters */
    private static final int CIRCLE_PRECISION = 48;

    public static List<LatLng> circle(LatLng center, double radiusMeters) {
        List<LatLng> points = Lists.newArrayListWithCapacity(CIRCLE_PRECISION);
        final double lat1 = degToRad(center.latitude);
        final double lon1 = degToRad(center.longitude);
        final double r = radiusMeters / EARTH_RADIUS;

        final double sinlat1 = sin(lat1);
        final double coslat1 = cos(lat1);
        final double sinr = sin(r);
        final double cosr = cos(r);

        for (int i = 0; i < CIRCLE_PRECISION; ++i) {
            final double θ = -i * (2*PI / (double)CIRCLE_PRECISION);
            final double lat2 = asin(sinlat1 * cosr + coslat1 * sinr * cos(θ));
            final double lon2 = lon1 + atan2(sin(θ)*sinr*coslat1, cosr - sinlat1*sin(lat2));
            points.add(radToDeg(lat2, lon2));
        }

        return points;
    }

    private static double degToRad(double degrees) {
        return degrees * (PI / 180.0);
    }
    private static double radToDeg(double radians) {
        return radians * (180.0 / PI);
    }
    private static LatLng radToDeg(double lat, double lng) {
        return new LatLng(radToDeg(lat), radToDeg(lng));
    }
}