move all comparators to a new package

extract interface and common implementation details of sorting

1 files changed, 42 insertions, 0 deletions

diff --git a/src/cgeo/geocaching/sorting/AbstractCacheComparator.java b/src/cgeo/geocaching/sorting/AbstractCacheComparator.java
new file mode 100644
index 0000000..4630888
--- /dev/null
+++ b/src/cgeo/geocaching/sorting/AbstractCacheComparator.java
@@ -0,0 +1,42 @@
+package cgeo.geocaching.sorting;
+
+import android.util.Log;
+import cgeo.geocaching.cgCache;
+import cgeo.geocaching.cgSettings;
+
+/**
+ * abstract super implementation for all cache comparators
+ *
+ */
+public abstract class AbstractCacheComparator implements CacheComparator {
+
+	@Override
+	public final int compare(cgCache cache1, cgCache cache2) {
+		try {
+			// first check that we have all necessary data for the comparison
+			if (!canCompare(cache1, cache2)) {
+				return 0;
+			}
+			return compareCaches(cache1, cache2);
+		} catch (Exception e) {
+			Log.e(cgSettings.tag, "AbstractCacheComparator.compare: " + e.toString());
+		}
+		return 0;
+	}
+
+	/**
+	 * check necessary preconditions (like missing fields) before running the comparison itself
+	 * @param cache1
+	 * @param cache2
+	 * @return
+	 */
+	protected abstract boolean canCompare(final cgCache cache1, final cgCache cache2);
+
+	/**
+	 * compares two caches. Logging and exception handling is implemented outside this method already.
+	 * @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 cgCache cache1, final cgCache cache2);
+}