如何在地图上显示两个地理位置之间的距离？

Question

我正在开发一个应用程序，用户必须在其中记录位置然后定位汽车。当他选择“定位汽车”选项时，应该显示停放的汽车。我计算了距离，但距离始终显示为0米。任何人都告诉如何在地图上显示人与车之间的距离...我想在地图上显示所停的汽车

Answer 1

you saved the position of the parked car? you've got the actual position of the person? so, then you should be able to calculate the difference and get at least the distance (at least of the line in sight)...

Answer 2

If you have the position of USER and parked car...

then this should work

Location locationA = new Location("USER");  

locationA.setLatitude(latA);  
locationA.setLongitude(lngA);  

Location locationB = new Location("Parked Car");  

locationB.setLatitude(latB);  
LocationB.setLongitude(lngB);  

distance = locationA.distanceTo(locationB); 

Answer 3

Use this function which calculates the real distance:

public static double distFrom (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).doubleValue();
}

and use it like this:

double distance = 0;
distance=distFrom(latA,lngA,latB,lngB);

if you want to convert the double to integer use this:

int distance=0;
distance=(int) distFrom(latA,lngA,latB,lngB);