AggregatedStatisticsActivity: added filter option (by category, start and/or end date).

Fixes #1039.

src/main/java/de/dennisguse/opentracks/util/StringUtils.java

@@ -29,6 +29,7 @@ import java.text.DecimalFormat;
 import java.time.Duration;
 import java.time.Instant;
 import java.time.LocalDateTime;
+import java.time.ZoneId;
 import java.time.ZoneOffset;
 import java.time.ZonedDateTime;
 import java.time.format.DateTimeFormatter;
@@ -61,6 +62,13 @@ public class StringUtils {
                 + " " + DateUtils.formatDateTime(context, time.toEpochMilli(), DateUtils.FORMAT_SHOW_TIME);
     }
 
+    /**
+     * Formats the date and time based on user's phone date/time preferences.
+     */
+    public static String formatDate(Context context, LocalDateTime localDateTime) {
+        return DateUtils.formatDateTime(context, localDateTime.atZone(ZoneId.systemDefault()).toInstant().toEpochMilli(), DateUtils.FORMAT_SHOW_DATE);
+    }
+
     /**
      * Formats the time using the ISO 8601 date time format with fractional seconds in UTC time zone.
      */