Prevent memory leaks

app/src/main/java/de/danoeh/antennapod/activity/AudioplayerActivity.java

@@ -110,6 +110,16 @@ public class AudioplayerActivity extends MediaplayerActivity implements NavDrawe
         saveCurrentFragment();
     }
 
+    @Override
+    public void onDestroy() {
+        super.onDestroy();
+        // don't risk creating memory leaks
+        navAdapter = null;
+        drawerToggle = null;
+        mPager = null;
+        mPagerAdapter = null;
+    }
+
     @Override
     protected void chooseTheme() {
         setTheme(UserPreferences.getNoTitleTheme());

app/src/main/java/de/danoeh/antennapod/fragment/ChaptersFragment.java

@@ -55,6 +55,11 @@ public class ChaptersFragment extends ListFragment implements AudioplayerContent
         }
     }
 
+    public void onDestroy() {
+        super.onDestroy();
+        adapter = null;
+    }
+
     @Override
     public void onDataSetChanged(Playable media) {
         adapter.setMedia(media);

app/src/main/java/de/danoeh/antennapod/fragment/CoverFragment.java

@@ -98,6 +98,11 @@ public class CoverFragment extends Fragment implements
 
     @Override
     public void onDataSetChanged(Playable media) {
+    public void onDestroy() {
+        super.onDestroy();
+        // prevent memory leaks
+        root = null;
+    }
         this.media = media;
         loadMediaInfo();
     }