像这样的怎么样。

public class Location {
    private static final double KILOMETERS_PER_NAUTICAL_MILE = 1.852;
    final String name;
    final double longitude;
    final double latitude;

    /**
     * Creates a (geo-location) with latitude and longitude
     * @param name the name of the location
     * @param latitude in degrees
     * @param longitude in degrees
     */
    public Location(String name, double latitude, double longitude) {
        this.name = name;
        this.latitude  = latitude;
        this.longitude = longitude;
    }

    /**
     * Computes the distance between this location and another location
     * measured in kilometers
     */
    public double distanceTo(Location that) {
        double lat1 = Math.toRadians(this.latitude);
        double lon1 = Math.toRadians(this.longitude);
        double lat2 = Math.toRadians(that.latitude);
        double lon2 = Math.toRadians(that.longitude);

        // great circle distance in radians, using law of cosines formula
        double angle = Math.acos(Math.sin(lat1) * Math.sin(lat2)
                               + Math.cos(lat1) * Math.cos(lat2) * Math.cos(lon1 - lon2));

        // each degree on a great circle of Earth is 60 nautical miles
        double nauticalMiles = 60 * Math.toDegrees(angle);
        return KILOMETERS_PER_NAUTICAL_MILE * nauticalMiles;
    }

    // return string representation of this point
    public String toString() {
        return name + " (" + latitude + ", " + longitude + ")";
    }
}

public class Route {
    private List<Location> points = new ArrayList<>();

    public void add(Location location) {
        points.add(location);
    }

    /**
     * Computes the location (by extrapolation) on the route after a given time at a
     * given speed
     * 
     * @param speed      constant speed (kilometers/hour)
     * @param elapseTime elapse time (seconds)
     * @return the extrapolated location on the route
     */
    public Location computeLocation(double speed, long elapseTime) {
        return computeLocation(speed * elapseTime / 3600d)
    }

    /**
     * Computes the location (by extrapolation) on the route after traveling a given distance
     * 
     * @param traveledDistance      traveled distance (kilometers)
     * @return the extrapolated location on the route
     */
    public Location computeLocation(double traveledDistance) {
        for (int i = 1; i < points.size(); i++) {
            Location start = points.get(i - 1);
            Location end = points.get(i);
            double dist = start.distanceTo(end);
            if (dist < traveledDistance) {
                // continue to the next segment
                traveledDistance -= dist;
            } else {
                // the final location is somewhere on current segment
                double ratio = traveledDistance / dist;
                return new Location(
                    "somewhere between " + start.name + " and " + end.name, 
                    start.latitude * (1.0 - ratio) + end.latitude * ratio, 
                    start.longitude * (1.0 - ratio) + end.longitude * ratio);
            }
        }
        // we reached the end of the route (traveled distance is > route length)
        return points.get(points.size() - 1);
    }
}

外推是在路线的2个点之间线性计算的（在纬度和经度上）。