Question

我从我的数据库中获取包含TITLE，SNIPPET和LOCATION的数据，并尝试测试以检查我当前位置之间的距离。我很困惑如何显示最接近我位置的标记的标题。

    List<MyMarkerObj> m = data.getMyMarkers();
                for (int i = 0; i < m.size(); i++) {
                    String[] slatlng =  m.get(i).getPosition().split(" ");
                    LatLng lat = new LatLng(Double.valueOf(slatlng[0]), Double.valueOf(slatlng[1]));
                    map.addMarker(new MarkerOptions()
                            .title(m.get(i).getTitle())
                            .snippet(m.get(i).getSnippet())
                            .icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_AZURE))
                            .position(lat)
                            );

                    float[] distance = new float[1];
                    Location.distanceBetween(currentlat, currentlong,Double.valueOf(slatlng[0]), Double.valueOf(slatlng[1]), distance);
                    Toast.makeText(getActivity(), "Marker Distance: "+ m.get(i).getTitle() +" "+distance[0], Toast.LENGTH_LONG).show();

                }

Answer 1

我在这里做了一些改变。试试吧..

List<MyMarkerObj> m = data.getMyMarkers();
float mindist;
int pos=0;
            for (int i = 0; i < m.size(); i++) {
                String[] slatlng =  m.get(i).getPosition().split(" ");
                LatLng lat = new LatLng(Double.valueOf(slatlng[0]), Double.valueOf(slatlng[1]));
                map.addMarker(new MarkerOptions()
                        .title(m.get(i).getTitle())
                        .snippet(m.get(i).getSnippet())
                        .icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_AZURE))
                        .position(lat)
                        );

                float[] distance = new float[1];
                Location.distanceBetween(currentlat, currentlong,Double.valueOf(slatlng[0]), Double.valueOf(slatlng[1]), distance);
                if(i==0) mindist=distance[0];
                else if(mindist>distance[0]) {
                   mindist=distance[0];
                   pos=i;
                 }
            }
  Toast.makeText(getActivity(), "Closest Marker Distance: "+ m.get(pos).getTitle() +" "+mindist, Toast.LENGTH_LONG).show();

Answer 2

您可以使用此简单函数计算纬度和经度格式中两点之间的距离，它就像一个魅力，然后您可以检查距您所在位置最近的距离。只需传递两个位置的纬度和经度

public double distanceFrom(double lat1, double lng1, double lat2, double lng2) {
    double earthRadius = 3958.75;
    double dLat = Math.toRadians(lat2-lat1);
    double dLng = Math.toRadians(lng2-lng1);
    double a = Math.sin(dLat/2) * Math.sin(dLat/2) + Math.cos(Math.toRadians(lat1)) * Math.cos(Math.toRadians(lat2)) * Math.sin(dLng/2) * Math.sin(dLng/2);
    double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
    double dist = earthRadius * c;
    int meterConversion = 1609;
    return new Double(dist * meterConversion).floatValue();    // this will return distance
}

从我当前位置Google Maps v2显示最接近标记的标题

2 个答案: