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package cgeo.geocaching.sorting;
import cgeo.geocaching.Geocache;
import cgeo.geocaching.utils.Log;
import org.apache.commons.lang3.StringUtils;
/**
* abstract super implementation for all cache comparators
*
*/
abstract class AbstractCacheComparator implements CacheComparator {
@Override
public final int compare(final Geocache cache1, final Geocache cache2) {
try {
final boolean canCompare1 = canCompare(cache1);
final boolean canCompare2 = canCompare(cache2);
if (!canCompare1) {
return canCompare2 ? 1 : fallbackToGeocode(cache1, cache2);
}
return canCompare2 ? compareCaches(cache1, cache2) : -1;
} catch (final Exception e) {
Log.e("AbstractCacheComparator.compare", e);
// This may violate the Comparator interface if the exception is not systematic.
return fallbackToGeocode(cache1, cache2);
}
}
private static int fallbackToGeocode(final Geocache cache1, final Geocache cache2) {
return StringUtils.defaultString(cache1.getGeocode()).compareToIgnoreCase(StringUtils.defaultString(cache2.getGeocode()));
}
/**
* Check necessary preconditions (like missing fields) before running the comparison itself.
* Caches not filling the conditions will be placed last, sorted by Geocode.
*
* The default returns <code>true</code> and can be overridden if needed in child classes.
*
* @param cache
* @return <code>true</code> if the cache holds the necessary data to be compared meaningfully
*/
@SuppressWarnings("static-method")
protected boolean canCompare(final Geocache cache) {
return true;
}
/**
* Compares two caches. Logging and exception handling is implemented outside this method already.
* <p/>
* A cache is smaller than another cache if it is desirable to show it first when presented to the user.
* For example, a highly rated cache must be considered smaller than a poorly rated one.
*
* @param cache1
* @param cache2
* @return an integer < 0 if cache1 is less than cache2, 0 if they are equal, and > 0 if cache1 is greater than
* cache2.
*/
protected abstract int compareCaches(final Geocache cache1, final Geocache cache2);
}
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