Question

大家好我正在开发一个Android应用程序，而移动那里的设备是一个保存的位置（latlng对象）在数组中，我希望它提醒用户离他的设备最近的地方，但它可能是最靠近下摆的地方下摆前面，如下图所示： ng2-admin

这是位置列表

List<LatLng> cameraLocation = new ArrayList<>();

这里我如何计算距离

  for (LatLng location : cameraLocation) {
                    closestCamera = location;
                    smallestDistance = distance;
                    Log.e("distanceTest", distance + "");
                    Log.d("closestCamera" , location+"" );
                    distanceList.add(CalculationByDistance(myLocation, location));
                    distance = Collections.min(distanceList);

                }

CalculationByDistance函数就像这样

public double CalculationByDistance(LatLng StartP, LatLng EndP) {
        int Radius = 6371;// radius of earth in Km
        double lat1 = StartP.latitude;
        double lat2 = EndP.latitude;
        double lon1 = StartP.longitude;
        double lon2 = EndP.longitude;
        double dLat = Math.toRadians(lat2 - lat1);
        double dLon = Math.toRadians(lon2 - lon1);
        double a = Math.sin(dLat / 2) * Math.sin(dLat / 2)
                + Math.cos(Math.toRadians(lat1))
                * Math.cos(Math.toRadians(lat2)) * Math.sin(dLon / 2)
                * Math.sin(dLon / 2);
        double c = 2 * Math.asin(Math.sqrt(a));
        double valueResult = Radius * c;
        double km = valueResult / 1;
        DecimalFormat newFormat = new DecimalFormat("#");
        int kmInDec = Integer.valueOf(newFormat.format(km));
        double meter = valueResult % 1000;
        int meterInDec = Integer.valueOf(newFormat.format(meter));
        Log.i("Radius Value", "" + valueResult + "   KM  " + kmInDec
                + " Meter   " + meterInDec);

        return Radius * c;
    }

任何帮助请...

Answer 1

您的班级可以有两个Location个实例，第一个currentLocation和第二个lastLocation。计算place与currentLocation和lastLocation之间的距离。 currentLocation与place greater之间的距离是lastLocation与place之间的距离，而不是place之间的距离private Location currentLocation; private Location lastLocation; public void onLocationUpdate(Location location){ lastLocation = currentLocation; currentLocation = location; calculateDistance(); } private double smallestDistance; private LatLng closestCamera; private void calculateDistance(){ for (LatLng location : cameraLocation) { double distanceFromLastLocation = CalculationByDistance(new LatLng(lastLocation.lat, lastLocation.lng), location); double distanceFromCurrentLocation = CalculationByDistance(new LatLng(lastLocation.lat, lastLocation.lng), location); if (distanceFromCurrentLocation < distanceFromLastLocation) { continue; // User is going away from location i.e location is behind user. No need to calculate distance between user and cameraLocation. } distanceList.add(CalculationByDistance(myLocation, location)); if (Collections.min(distanceList) == distanceFromCurrentLocation) { // this location is nearest amongst all the cameraLocations. smallestDistance = distanceFromCurrentLocation; closestCamera = location; } } } }。那个地方在你当前的位置后面。

示例代码：

{{1}}

如何找到最近的latlng阵列的位置到我的位置和我的前面不在我身后

1 个答案: