public int distance(int zip1, int zip2){
    final double EARTH_RADIUS = 3959.0;
    boolean unFound = true;
    int i = 0;
    double lat1 = 0;    double lon1 = 0;    // zip code 1
    double lat2 = 0;    double lon2 = 0;    // zip code 2
    double p1 = 0;      double p2 = 0;
    double p3 = 0;      int distance = 0;
    double answer = 0; 
 
    while(unFound == false &&  i < zips.size()){
        
       if(zips.get(i).getZip() == zip1){
           lat1 = Math.toRadians(zips.get(i).getLatitude());
           lon1 = Math.toRadians(zips.get(i).getLongitude());
        }else if(zips.get(i).getZip() == zip2){
            lat2 = Math.toRadians(zips.get(i).getLatitude());
            lon2 = Math.toRadians(zips.get(i).getLongitude());
            
        }  
            p1 = (Math.cos(lat1) * Math.cos(lon1) * Math.cos(lat2) * Math.cos(lon2));
            p2 = Math.cos(lat1) * Math.sin(lon1) * Math.cos(lat2) * Math.sin(lon2);
            p3 = Math.sin(lat1) * Math.sin(lat2);
            answer = Math.acos(p1+p2+p3) * 3959;
                //System.out.println("" +  distance );
            distance = (int)(answer);  

}return distance;
}