I'm developing an Android app. I've looked online, and tried a few things, but haven't gotten anything to work. I'm trying to run a static inner class in my Android app. It sorts an ArrayList for me. I tried the following:
GenericCachedSorter sort = new GenericCachedSorter();
sort.main(Longitude1);
sort.sort(distancetos, null);
and
new GenericCachedSorter();
GenericCachedSorter.main(Longitude1);
But both gave NPE on those lines of code. I'm not sure why this isn't working. My code is below:
NearestStations.java
public class Neareststations extends Activity implements LocationListener {
LocationManager mLocationManager;
double longitude;
double latitude;
String distancea;
String distance1;
static Map<String, String> myMap1 = new HashMap<String, String>();
static ArrayList<Double> distancetos = new ArrayList<Double>();
@SuppressLint("NewApi")
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.neareststations);
// Show the Up button in the action bar.
getActionBar().setDisplayHomeAsUpEnabled(true);
List<String> Lat1 = Arrays.asList(getResources().getStringArray(R.array.Latitude));
Log.i("Lat1", String.valueOf(Lat1.get(0)));
String[] Stations = getResources().getStringArray(R.array.Stations);
String[] Longitude = getResources().getStringArray(R.array.Longitude);
for (int h = 0; h <144; h++) {
myMap1.put(Stations[h], Longitude[h]);
}
mLocationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
Location location = mLocationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
longitude = location.getLongitude();
latitude = location.getLatitude();
if(location != null && location.getTime() > Calendar.getInstance().getTimeInMillis() - 2 * 60 * 1000) {
{
}
}
else {
mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 5, 50, this);
Log.i("MYTAG", String.valueOf(location));
}
longitude = location.getLongitude();
latitude = location.getLatitude();
if (location != null) {
longitude = location.getLongitude();
latitude = location.getLatitude();
Log.i("MYTAG", String.valueOf(longitude));
Log.i("MYTAG", String.valueOf(latitude));
List<String> Long = Arrays.asList(getResources().getStringArray(R.array.Longitude));
List<String> Lat = Arrays.asList(getResources().getStringArray(R.array.Latitude));
Log.i("Long1", String.valueOf(Long.get(0)));
Iterator<String> iterator = Lat.iterator();
Iterator<String> iterator1 = Long.iterator();
ArrayList<Double> longitudeArray = new ArrayList<Double>();
while(iterator.hasNext()){
for (int i=0; i<144;i++){
double distance = 0;
double lat_end = 0;
double lon_end = 0;
try {
lat_end = Double.parseDouble(iterator.next());
lon_end = Double.parseDouble(iterator1.next());
longitudeArray.add((lon_end));
} catch (NumberFormatException e) {
Log.v("Main", "Convert to Double Failed : ");
}
Location locationA = new Location("point A");
locationA.setLatitude(latitude);
locationA.setLongitude(longitude);
Location locationB = new Location("point B");
locationB.setLatitude(lat_end);
locationB.setLongitude(lon_end);
distance = locationA.distanceTo(locationB) * 0.000621371192237334;
String dista = Double.toString(distance);
distancetos.add(Double.parseDouble(dista));
}
}
Collections.sort(distancetos);
distancea = distancetos.get(0).toString();
distance1 = distancetos.get(1).toString();
String Longa = longitudeArray.get(0).toString();
String Long1 = longitudeArray.get(1).toString();
String[] Stations1 = getResources().getStringArray(R.array.Stations);
String[] Longitude1 = getResources().getStringArray(R.array.Longitude);
String[] Latitude = getResources().getStringArray(R.array.Latitude);
Map<String, String> myMap = new HashMap<String, String>();{
for (int i = 0; i <144; i++) {
myMap.put(Latitude[i], Stations1[i]);
}
}
Map<String, String> myMap1 = new HashMap<String, String>();{
for (int h = 0; h <144; h++) {
myMap1.put(Longitude1[h], Stations1[h]);
}
}
String value = myMap1.get(Longa);
}
}
public void onLocationChanged(Location location) {
}
public void onProviderDisabled(String arg0) {}
public void onProviderEnabled(String arg0) {}
public void onStatusChanged(String arg0, int arg1, Bundle arg2) {}
public static class GenericCachedSorter {
public static void main(String[] args) {
sort(distancetos, new ToComparable<Double, Double>() {
@Override
public Double toComparable(Double distance) {
// return the longitude associated with this distance
return (Double.parseDouble(myMap1.get(distance)));
}
});
for (Double distance : distancetos)
System.out.println(distancetos);
}
public interface ToComparable<T, C extends Comparable<? super C>> {
C toComparable(T t);
}
public static <T, C extends Comparable<? super C>> void sort(List<T> list, ToComparable<T, C> function) {
class Pair implements Comparable<Pair> {
final T original;
final C comparable;
Pair(T original, C comparable) {
this.original = original;
this.comparable = comparable;
}
@Override
public int compareTo(Pair other) {
return
comparable == null && other.comparable == null ? 0 :
comparable == null ? -1 :
other.comparable == null ? 1 :
comparable.compareTo(other.comparable);
}
}
List<Pair> pairs = new ArrayList<Pair>(list.size());
for (T original : list)
pairs.add(new Pair(original, function.toComparable(original)));
Collections.sort(pairs);
ListIterator<T> iter = list.listIterator();
for (Pair pair : pairs) {
iter.next();
iter.set(pair.original);
}
}
}
}
Thank you for your help.
