Further improve image loading, and remove unused code.

app/src/main/java/fr/free/nrw/commons/CommonsApplication.java

@@ -84,7 +84,6 @@ public class CommonsApplication extends Application {
     private AbstractHttpClient httpClient = null;
     private MWApi api = null;
     private CacheController cacheData = null;
-    private RequestQueue volleyQueue = null;
     private DBOpenHelper dbOpenHelper = null;
     private NearbyPlaces nearbyPlaces = null;
 
@@ -139,15 +138,6 @@ public class CommonsApplication extends Application {
         return cacheData;
     }
 
-    public RequestQueue getVolleyQueue() {
-        if (volleyQueue == null) {
-            DiskBasedCache cache = new DiskBasedCache(getCacheDir(), 16 * 1024 * 1024);
-            volleyQueue = new RequestQueue(cache, new BasicNetwork(new HurlStack()));
-            volleyQueue.start();
-        }
-        return volleyQueue;
-    }
-
     public synchronized DBOpenHelper getDBOpenHelper() {
         if (dbOpenHelper == null) {
             dbOpenHelper = new DBOpenHelper(this);
@@ -190,12 +180,7 @@ public class CommonsApplication extends Application {
         cacheData  = new CacheController();
 
         DiskBasedCache cache = new DiskBasedCache(getCacheDir(), 16 * 1024 * 1024);
-        volleyQueue = new RequestQueue(cache, new BasicNetwork(new HurlStack()));
+        new RequestQueue(cache, new BasicNetwork(new HurlStack())).start();
-        volleyQueue.start();
-    }
-
-    public MWApi getApi() {
-        return api;
     }
 
     /**
@@ -262,15 +247,14 @@ public class CommonsApplication extends Application {
         preferences.edit().clear().commit();
         context.getSharedPreferences("prefs", Context.MODE_PRIVATE).edit().clear().commit();
         preferences.edit().putBoolean("firstrun", false).apply();
-        updateAllDatabases(context);
+        updateAllDatabases();
         currentAccount = null;
     }
 
     /**
      * Deletes all tables and re-creates them.
-     * @param context context
      */
-    public void updateAllDatabases(Context context) {
+    public void updateAllDatabases() {
         DBOpenHelper dbOpenHelper = CommonsApplication.getInstance().getDBOpenHelper();
         dbOpenHelper.getReadableDatabase().close();
         SQLiteDatabase db = dbOpenHelper.getWritableDatabase();

app/src/main/java/fr/free/nrw/commons/MediaThumbnailFetchTask.java

@@ -1,11 +1,17 @@
 package fr.free.nrw.commons;
 
 import android.os.AsyncTask;
+import android.support.annotation.NonNull;
 
 import org.mediawiki.api.ApiResult;
 
 class MediaThumbnailFetchTask extends AsyncTask<String, String, String> {
     private static final String THUMB_SIZE = "640";
+    protected final Media media;
+
+    public MediaThumbnailFetchTask(@NonNull Media media) {
+        this.media = media;
+    }
 
     @Override
     protected String doInBackground(String... params) {

app/src/main/java/fr/free/nrw/commons/MediaWikiImageView.java

@@ -1,6 +1,7 @@
 package fr.free.nrw.commons;
 
 import android.content.Context;
+import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import android.support.v4.util.LruCache;
 import android.util.AttributeSet;
@@ -27,15 +28,16 @@ public class MediaWikiImageView extends SimpleDraweeView {
         if (currentThumbnailTask != null) {
             currentThumbnailTask.cancel(true);
         }
-        setImageURI((String) null);
         if(media == null) {
+            setImageURI((String) null);
             return;
         }
 
         if (thumbnailUrlCache.get(media.getFilename()) != null) {
             setImageUrl(thumbnailUrlCache.get(media.getFilename()));
         } else {
-            currentThumbnailTask = new ThumbnailFetchTask();
+            setImageURI((String) null);
+            currentThumbnailTask = new ThumbnailFetchTask(media);
             currentThumbnailTask.execute(media.getFilename());
         }
     }
@@ -53,11 +55,16 @@ public class MediaWikiImageView extends SimpleDraweeView {
     }
 
     private class ThumbnailFetchTask extends MediaThumbnailFetchTask {
+        ThumbnailFetchTask(@NonNull Media media) {
+            super(media);
+        }
+
         @Override
         protected void onPostExecute(String result) {
             if (isCancelled()) {
                 return;
             }
+            thumbnailUrlCache.put(media.getFilename(), result);
             setImageUrl(result);
         }
     }