calculating distance between successive csv gps points using java

here is part of code that i tried to execute but it dosent work ... the problem is in latitude2 and longitude i didnt figure out calculate distance between row and row+1 nay help please !!!!

                             BufferedReader reader = new BufferedReader(new FileReader(file));
try {
    /* First line of the data file is the header */
    String line = reader.readLine();
    System.out.println("Header: " + line);

    boolean foundAnyRowHigherThan5 = false;
    boolean checker = true;
    double currentLongitude = 0;
    double currentLatitude = 0;


    for (line = reader.readLine(); line != null; line = reader.readLine()) {
        if (line.trim().length() > 0) { // skip blank lines
            {
                if(checker){
                String currentTokens[] = line.split("\\,");
                String currentName1 = currentTokens[0].trim();
                String currentName2 = currentTokens[1].trim();
                currentLatitude = Double.parseDouble(currentTokens[2]);
                currentLongitude = Double.parseDouble(currentTokens[3]);
                checker = false;
                continue;
                } 




            String tokens[] = line.split("\\,");
            String name1 = tokens[0].trim();
            String name2 = tokens[1].trim();
            double latitude = Double.parseDouble(tokens[2]);
            double longitude = Double.parseDouble(tokens[3]);

            double latitude2 = latitude - currentLatitude;
            double longitude2 = longitude - currentLongitude;

            String speedString = tokens[5].trim();
            double dist = Double.parseDouble(tokens[4]);
            float speedFloat = Float.parseFloat(speedString);



          if(foundAnyRowHigherThan5 || speedFloat > 5.0) {
            // a partir de ce point on ajoutera touts les points ,
            if(!foundAnyRowHigherThan5) {
              foundAnyRowHigherThan5 = true;
            }

            /* Longitude (= x coord) first ! */
            Point point = geometryFactory.createPoint(new Coordinate(longitude, latitude));

            featureBuilder.add(point);

            double earthRadius = 6371; //kilometers

            double dLat = Math.toRadians(latitude-latitude2);
            double dLng = Math.toRadians(longitude-longitude2);
            double a = Math.sin(dLat/2) * Math.sin(dLat/2) +
                       Math.cos(Math.toRadians(latitude)) * Math.cos(Math.toRadians(latitude2)) *
                       Math.sin(dLng/2) * Math.sin(dLng/2);
            double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
             dist = (double) (earthRadius * c);


            featureBuilder.add(name1);
            featureBuilder.add(name2);

            featureBuilder.add(speedString);
            featureBuilder.add(dist);
            SimpleFeature feature = featureBuilder.buildFeature(null);

            features.add(feature);

            currentLatitude = latitude;
            currentLongitude = longitude;


            }
        }
    }

    }  
} 
    finally {
    reader.close();
}