Small cleanups and improvements code.

src/androidTest/java/de/dennisguse/opentracks/io/file/importer/ExportImportTest.java

@@ -1,7 +1,6 @@
 package de.dennisguse.opentracks.io.file.importer;
 
 import android.content.Context;
-import android.database.sqlite.SQLiteConstraintException;
 import android.util.Log;
 import android.util.Pair;
 
@@ -10,9 +9,7 @@ import androidx.test.filters.LargeTest;
 
 import org.junit.After;
 import org.junit.Before;
-import org.junit.Rule;
 import org.junit.Test;
-import org.junit.rules.ExpectedException;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
 
@@ -62,9 +59,6 @@ public class ExportImportTest {
     private Track.Id importTrackId;
     private final Track.Id trackId = new Track.Id(System.currentTimeMillis());
 
-    @Rule
-    public ExpectedException exception = ExpectedException.none();
-
     @Before
     public void setUp() {
         Pair<Track, TrackPoint[]> track = TestDataUtil.createTrack(trackId, 10);
@@ -179,7 +173,7 @@ public class ExportImportTest {
     }
 
     @LargeTest
-    @Test
+    @Test(expected = ImportAlreadyExistsException.class)
     public void kml_with_trackdetail_and_sensordata_duplicate_trackUUID() {
         // given
         PreferencesUtils.setBoolean(context, R.string.import_prevent_reimport_key, true);
@@ -187,8 +181,6 @@ public class ExportImportTest {
 
         TrackExporter trackExporter = TrackFileFormat.KML_WITH_TRACKDETAIL_AND_SENSORDATA.newTrackExporter(context);
 
-        exception.expect(ImportAlreadyExistsException.class);
-
         // when
         // 1. export
         ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
@@ -270,7 +262,7 @@ public class ExportImportTest {
     }
 
     @LargeTest
-    @Test
+    @Test(expected = ImportAlreadyExistsException.class)
     public void gpx_duplicate_trackUUID() {
         // given
         PreferencesUtils.setBoolean(context, R.string.import_prevent_reimport_key, true);
@@ -278,8 +270,6 @@ public class ExportImportTest {
 
         TrackExporter trackExporter = TrackFileFormat.GPX.newTrackExporter(context);
 
-        exception.expect(ImportAlreadyExistsException.class);
-
         // when
         // 1. export
         ByteArrayOutputStream outputStream = new ByteArrayOutputStream();

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

@@ -4,6 +4,8 @@ import android.os.Bundle;
 import android.os.Handler;
 import android.os.ResultReceiver;
 
+import androidx.annotation.NonNull;
+
 /**
  * Create a new ResultReceive to receive results.
  * Your {@link #onReceiveResult} method will be called from the thread running <var>handler</var> if given, or from an arbitrary thread if null.
@@ -15,18 +17,16 @@ public class ExportServiceResultReceiver extends ResultReceiver {
 
     public static final String RESULT_EXTRA_TRACK_ID = "result_extra_track_id";
 
-    private Receiver receiver;
+    private final Receiver receiver;
 
-    public ExportServiceResultReceiver(Handler handler, Receiver receiver) {
+    public ExportServiceResultReceiver(Handler handler, @NonNull Receiver receiver) {
         super(handler);
         this.receiver = receiver;
     }
 
     @Override
     protected void onReceiveResult(int resultCode, Bundle resultData) {
-        if (receiver != null) {
-            receiver.onReceiveResult(resultCode, resultData);
-        }
+        receiver.onReceiveResult(resultCode, resultData);
     }
 
     public interface Receiver {

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

@@ -4,6 +4,8 @@ import android.os.Bundle;
 import android.os.Handler;
 import android.os.ResultReceiver;
 
+import androidx.annotation.NonNull;
+
 /**
  * Create a new ResultReceive to receive results.
  * Your {@link #onReceiveResult} method will be called from the thread running <var>handler</var> if given, or from an arbitrary thread if null.
@@ -18,18 +20,16 @@ public class ImportServiceResultReceiver extends ResultReceiver {
     public static final String RESULT_EXTRA_FILENAME = "result_extra_filename";
     public static final String RESULT_EXTRA_MESSAGE = "result_extra_message";
 
-    private Receiver receiver;
+    private final Receiver receiver;
 
-    public ImportServiceResultReceiver(Handler handler, Receiver receiver) {
+    public ImportServiceResultReceiver(Handler handler, @NonNull Receiver receiver) {
         super(handler);
         this.receiver = receiver;
     }
 
     @Override
     protected void onReceiveResult(int resultCode, Bundle resultData) {
-        if (receiver != null) {
-            receiver.onReceiveResult(resultCode, resultData);
-        }
+        receiver.onReceiveResult(resultCode, resultData);
     }
 
     public interface Receiver {