#2966 RxJava2 null - explicit mark underlying Rx sources as NonNull

to be on the safe side, for cases that the consuming observers checks null
unnecessarily.

Rx observer : underlying sources marked as NonNull
OnlineFeedViewActivity.startFeedDownload : Downloader.getResult
AllEpisodesFragment.loadItems : AllEpisodesFragment.loadData
PlaybackHistoryFragment.loadItems : DBReader.getPlaybackHistory
QueueFragment.loadItems : DBReader.getQueue
SearchFragment.search : .performSearch

4 files changed, 16 insertions, 3 deletions

diff --git a/core/src/main/java/de/danoeh/antennapod/core/service/download/Downloader.java b/core/src/main/java/de/danoeh/antennapod/core/service/download/Downloader.java
index 445210d3a..38b93eab8 100644
--- a/core/src/main/java/de/danoeh/antennapod/core/service/download/Downloader.java
+++ b/core/src/main/java/de/danoeh/antennapod/core/service/download/Downloader.java
@@ -2,6 +2,7 @@ package de.danoeh.antennapod.core.service.download;
 
 import android.content.Context;
 import android.net.wifi.WifiManager;
+import android.support.annotation.NonNull;
 
 import java.util.concurrent.Callable;
 
@@ -18,10 +19,12 @@ public abstract class Downloader implements Callable<Downloader> {
 
     volatile boolean cancelled;
 
+    @NonNull
     final DownloadRequest request;
+    @NonNull
     final DownloadStatus result;
 
-    Downloader(DownloadRequest request) {
+    Downloader(@NonNull DownloadRequest request) {
         super();
         this.request = request;
         this.request.setStatusMsg(R.string.download_pending);
@@ -54,10 +57,12 @@ public abstract class Downloader implements Callable<Downloader> {
         return this;
     }
 
+    @NonNull
     public DownloadRequest getDownloadRequest() {
         return request;
     }
 
+    @NonNull
     public DownloadStatus getResult() {
         return result;
     }
diff --git a/core/src/main/java/de/danoeh/antennapod/core/service/download/HttpDownloader.java b/core/src/main/java/de/danoeh/antennapod/core/service/download/HttpDownloader.java
index 842ad0c60..c27cefc10 100644
--- a/core/src/main/java/de/danoeh/antennapod/core/service/download/HttpDownloader.java
+++ b/core/src/main/java/de/danoeh/antennapod/core/service/download/HttpDownloader.java
@@ -1,5 +1,6 @@
 package de.danoeh.antennapod.core.service.download;
 
+import android.support.annotation.NonNull;
 import android.text.TextUtils;
 import android.util.Log;
 
@@ -38,7 +39,7 @@ public class HttpDownloader extends Downloader {
 
     private static final int BUFFER_SIZE = 8 * 1024;
 
-    public HttpDownloader(DownloadRequest request) {
+    public HttpDownloader(@NonNull DownloadRequest request) {
         super(request);
     }
 
diff --git a/core/src/main/java/de/danoeh/antennapod/core/storage/DBReader.java b/core/src/main/java/de/danoeh/antennapod/core/storage/DBReader.java
index 6c619fa31..86d2b8893 100644
--- a/core/src/main/java/de/danoeh/antennapod/core/storage/DBReader.java
+++ b/core/src/main/java/de/danoeh/antennapod/core/storage/DBReader.java
@@ -202,6 +202,7 @@ public final class DBReader {
         }
     }
 
+    @NonNull
     private static List<FeedItem> extractItemlistFromCursor(PodDBAdapter adapter, Cursor cursor) {
         List<FeedItem> result = new ArrayList<>(cursor.getCount());
 
@@ -254,6 +255,7 @@ public final class DBReader {
         return feed;
     }
 
+    @NonNull
     static List<FeedItem> getQueue(PodDBAdapter adapter) {
         Log.d(TAG, "getQueue()");
         Cursor cursor = null;
@@ -310,6 +312,7 @@ public final class DBReader {
      * @return A list of FeedItems sorted by the same order as the queue. The caller can wrap the returned
      * list in a {@link de.danoeh.antennapod.core.util.QueueAccess} object for easier access to the queue's properties.
      */
+    @NonNull
     public static List<FeedItem> getQueue() {
         Log.d(TAG, "getQueue() called");
 
@@ -418,6 +421,7 @@ public final class DBReader {
      *
      * @param limit The maximum number of episodes that should be loaded.
      */
+    @NonNull
     public static List<FeedItem> getRecentlyPublishedEpisodes(int limit) {
         Log.d(TAG, "getRecentlyPublishedEpisodes() called with: " + "limit = [" + limit + "]");
 
@@ -444,6 +448,7 @@ public final class DBReader {
      * @return The playback history. The FeedItems are sorted by their media's playbackCompletionDate in descending order.
      * The size of the returned list is limited by {@link #PLAYBACK_HISTORY_SIZE}.
      */
+    @NonNull
     public static List<FeedItem> getPlaybackHistory() {
         Log.d(TAG, "getPlaybackHistory() called");
 
diff --git a/core/src/main/java/de/danoeh/antennapod/core/storage/FeedSearcher.java b/core/src/main/java/de/danoeh/antennapod/core/storage/FeedSearcher.java
index f91e2ad08..4093c41a5 100644
--- a/core/src/main/java/de/danoeh/antennapod/core/storage/FeedSearcher.java
+++ b/core/src/main/java/de/danoeh/antennapod/core/storage/FeedSearcher.java
@@ -1,6 +1,7 @@
 package de.danoeh.antennapod.core.storage;
 
 import android.content.Context;
+import android.support.annotation.NonNull;
 
 import java.util.ArrayList;
 import java.util.Collections;
@@ -35,6 +36,7 @@ public class FeedSearcher {
      * @param selectedFeed feed to search, 0 to search through all feeds
      * @return list of episodes containing the query
      */
+    @NonNull
     public static List<SearchResult> performSearch(final Context context,
                                                    final String query, final long selectedFeed) {
         final int values[] = {2, 1, 0, 0, 0, 0};
@@ -45,7 +47,7 @@ public class FeedSearcher {
                 context.getString(R.string.found_in_authors_label),
                 context.getString(R.string.found_in_feeds_label)};
 
-        List<SearchResult> result = new ArrayList<>();
+        final List<SearchResult> result = new ArrayList<>();
 
         List<FutureTask<List<FeedItem>>> tasks = new ArrayList<>();
         tasks.add(DBTasks.searchFeedItemTitle(context, selectedFeed, query));