Cleanup using AndroidStudio analyze.

src/main/java/de/dennisguse/opentracks/io/file/exporter/GPXTrackExporter.java

@@ -310,7 +310,7 @@ public class GPXTrackExporter implements TrackExporter {
     }
 
     public Distance writeTrackPoint(ZoneOffset zoneOffset, TrackPoint trackPoint, List<TrackPoint> sensorPoints, Distance trackDistance) {
-        Distance cumulativeDistance = null;
+        Distance cumulativeDistance;
 
         printWriter.println("<trkpt " + formatLocation(trackPoint.getLatitude(), trackPoint.getLongitude()) + ">");
 

src/main/java/de/dennisguse/opentracks/io/file/exporter/KMLTrackExporter.java

@@ -498,7 +498,7 @@ public class KMLTrackExporter implements TrackExporter {
     }
 
     private void writeTypeLocalized(String localizedValue) {
-        if (localizedValue == null || localizedValue.equals("")) {
+        if (localizedValue == null || localizedValue.isEmpty()) {
             return;
         }
         printWriter.println("<ExtendedData>");

src/main/java/de/dennisguse/opentracks/io/file/importer/KmlTrackImporter.java

@@ -414,7 +414,7 @@ public class KmlTrackImporter extends DefaultHandler implements XMLImporter.Trac
         Float value = null;
         if (content != null) {
             content = content.trim();
-            if (!"".equals(content)) {
+            if (!content.isEmpty()) {
                 try {
                     value = Float.parseFloat(content);
                 } catch (NumberFormatException e) {