How to sum of arrays of floating point numbers

Question

How to sum of arrays of floating point numbers..as the results from distance that the array float come from results Location.distanceBetween(latStart, longStart, latB, longB, results); method in Google maps api ,,i'm trying with this, but at some point it decrease, it should always incrementing. what am i missing?

EDIT:

public float total(ArrayList<LatLng> listPoints){
        if(listPoints.size()==2){
            listPoints.clear();
        }
        listPoints.add(latLng);
        float[] results = new float[2];
        float sum  = 0.0f;
        for (int z = 0; z < listPoints.size(); z++) {
            if(listPoints.size() == 1){
                latStart = listPoints.get(z).latitude;
                longStart = listPoints.get(z).longitude;
                Toast.makeText(this, "listPoint 1", Toast.LENGTH_SHORT).show();
            }else if(listPoints.size() == 2){
                latB = listPoints.get(z).latitude;
                longB = listPoints.get(z).longitude;
                Toast.makeText(this, "listPoint 2", Toast.LENGTH_SHORT).show();
            }
            Location.distanceBetween(latStart, longStart, latB, longB, results);
            sum+=results[0];
        }
        tvJarakTotal.setText(sum + "");
        return sum;
    }

EDIT: the distance came from onLocationChanged() method as the user location is moving,

EDIT: I Finally find the solution myself, by creating some trick using sharedPreference. but the accepted answer is correct to the question.

Answer 1

It is not entirely clear what you think you were doing in your code above. First of all, the Location#distanceBetween API takes in a pair of latitude longitude values, i.e. two geographic points, and then returns the distance between them in results[0] (q.v. the documentation).

Next, it isn't clear what the starting and ending points are intended to be. I answered below under the assumption that the listPoints are one set of points (either starting or ending), and the vales latB and longB are a fixed set of starting/ending points. Without this assumption, an answer really can't be given here.

public float total(ArrayList<LatLng> listPoints) {
    float[] results;
    float sum = 0.0f;
    for (int z=0; z < listPoints.size(); z++) {
        double latStart = listPoints.get(z).latitude;
        double longStart = listPoints.get(z).longitude;
        Location.distanceBetween(latStart, longStart, latB, longB, results);
        sum += results[0];
        tvJarak.setText(sum + "");
    }

    return sum;
}