Mohsen Mohseni - 1 year ago 75

Android Question

I have an arrayList of markers and I want to find the closest marker to my current location.

I had no idea how to find that marker so I searched and found same problem in here.

Google Maps Api v3 - find nearest markers

then I tried to convert those code to java but it doesn't work now.

`closest`

Is there any better solution for this problem or I can make the following code usable?

`public void findNearMarker(){`

double pi = Math.PI;

int R = 6371; //equatorial radius

double[] distances = new double[2];

double d = 0;

int i;

int closest = -1;

for ( i = 0; i == markerArrayList.size(); i++){

double lat2 = markerArrayList.get(i).getPosition().latitude;

double lon2 = markerArrayList.get(i).getPosition().longitude;

double chLat = lat2 - currentLocation.getLatitude();

double chLon = lon2 - currentLocation.getLongitude();

double dLat = chLat*(pi/180);

double dLon = chLon*(pi/180);

double rLat1 = currentLocation.getLatitude()*(pi/180);

double rLat2 = lat2 * (pi/180);

double a = Math.sin(dLat/2) * Math.sin(dLat/2) + Math.sin(dLon/2)

* Math.sin(dLon /2) * Math.cos(rLat1) * Math.cos(rLat2);

double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));

d = R * c;

distances[i] = d;

if (closest == -1 || d< distances[closest]){

closest = i;

}

}

}

Answer Source

first you need to import the location class of the android sdk

```
import android.location.Location;
ArrayList<Marker> markers = new ArrayList<>();
markers = sortListbyDistance(markers, currentLocation.getLocation());
public static ArrayList<Marker> sortListbyDistance(ArrayList<Marker> radars, final LatLng location){
Collections.sort(markers, new Comparator<Marker>() {
@Override
public int compare(Marker marker2, Marker marker1) {
//
if(getDistanceBetweenPoints(marker1.getLocation(),location)>getDistanceBetweenPoints(marker2.getLocation(),location)){
return -1;
} else {
return 1;
}
}
});
return markers;
}
public static float getDistanceBetweenPoints(double firstLatitude, double firstLongitude, double secondLatitude, double secondLongitude) {
float[] results = new float[1];
Location.distanceBetween(firstLatitude, firstLongitude, secondLatitude, secondLongitude, results);
return results[0];
}
```

and to get the nearest marker just get first item in markers, cheers :)