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package cgeo.geocaching.sorting;
import cgeo.geocaching.Geocache;
import cgeo.geocaching.location.Geopoint;
import java.util.ArrayList;
import java.util.List;
/**
* sorts caches by distance to given position
*
*/
public class DistanceComparator extends AbstractCacheComparator {
final private Geopoint coords;
final private List<Geocache> list;
private boolean cachedDistances;
final static public DistanceComparator singleton = new DistanceComparator();
public DistanceComparator() {
// This constructor should not be used as a comparator as distances will not be updated.
// It is needed in order to really know we are sorting by Distances in the sort menu.
// If you need it for sorting, please use the second constructor.
coords = null;
list = new ArrayList<>();
}
public DistanceComparator(final Geopoint coords, final List<Geocache> list) {
this.coords = coords;
// create new list so we can iterate over the list in parallel with the cache list adapter
this.list = new ArrayList<>(list);
}
/**
* calculate all distances only once to avoid costly re-calculation of the same distance during sorting
*/
private void calculateAllDistances() {
if (cachedDistances) {
return;
}
for (final Geocache cache : list) {
if (cache.getCoords() != null) {
cache.setDistance(coords.distanceTo(cache.getCoords()));
}
}
cachedDistances = true;
}
@Override
protected int compareCaches(final Geocache cache1, final Geocache cache2) {
calculateAllDistances();
final Float distance1 = cache1.getDistance();
final Float distance2 = cache2.getDistance();
if (distance1 == null) {
return distance2 == null ? 0 : 1;
}
return distance2 == null ? -1 : Float.compare(distance1, distance2);
}
}
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