In this tutorial, we will show you how to calculate the distance between two locations geolocated by using latitude and longitude in Java. This distance calculation uses the **Spherical Law of Cosines**, which uses trigonometry to measure the curvature of the earth, to accurately measure the distances on the Earth.

```
import java.util.*;
import java.lang.*;
import java.io.*;
class DistanceCalculator
{
public static void main (String[] args) throws java.lang.Exception
{
System.out.println(distance(32.9697, -96.80322, 29.46786, -98.53506, "M") + " Miles\n");
System.out.println(distance(32.9697, -96.80322, 29.46786, -98.53506, "K") + " Kilometers\n");
System.out.println(distance(32.9697, -96.80322, 29.46786, -98.53506, "N") + " Nautical Miles\n");
}
private static double distance(double lat1, double lon1, double lat2, double lon2, String unit) {
if ((lat1 == lat2) && (lon1 == lon2)) {
return 0;
}
else {
double theta = lon1 - lon2;
double dist = Math.sin(Math.toRadians(lat1)) * Math.sin(Math.toRadians(lat2)) + Math.cos(Math.toRadians(lat1)) * Math.cos(Math.toRadians(lat2)) * Math.cos(Math.toRadians(theta));
dist = Math.acos(dist);
dist = Math.toDegrees(dist);
dist = dist * 60 * 1.1515;
if (unit.equals("K")) {
dist = dist * 1.609344;
} else if (unit.equals("N")) {
dist = dist * 0.8684;
}
return (dist);
}
}
}
```

The code above creates the function named **distance **to calculate the distance between two locations. It implies the simple spherical law of cosines that gives well-conditioned results down to distances as small as a few meters on the Earth’s surface. The distance function makes use of the spherical law of cosines formula `cos `

and derived into the distance calculation.*c* = cos *a* cos *b* + sin *a* sin *b* cos *C*

Parameters that are passed to the distance function are:**lat1**, **lon1** = Latitude and Longitude of point 1 in decimal degrees**lat2**, **lon2 **= Latitude and Longitude of point 2 in decimal degrees**unit **= the unit you desire for results where ‘M’ is the statute miles (default), ‘K’ is kilometers and ‘N’ is nautical miles