massively shorten code and improve readability via a menu helper

src/main/java/com/owncloud/android/files/FileMenuFilter.java

@@ -124,7 +124,12 @@ public class FileMenuFilter {
         }
     }
 
-    private static void hideMenuItem(MenuItem item) {
+    /**
+     * hides a given {@link MenuItem}.
+     *
+     * @param item the {@link MenuItem} to be hidden
+     */
+    public static void hideMenuItem(MenuItem item) {
         if (item != null) {
             item.setVisible(false);
             item.setEnabled(false);

src/main/java/com/owncloud/android/ui/preview/PreviewImageFragment.java

@@ -333,64 +333,20 @@ public class PreviewImageFragment extends FileFragment {
 
         // additional restriction for this fragment 
         // TODO allow renaming in PreviewImageFragment
-        MenuItem item = menu.findItem(R.id.action_rename_file);
-        if (item != null) {
-            item.setVisible(false);
-            item.setEnabled(false);
-        }
-
-        // additional restriction for this fragment 
         // TODO allow refresh file in PreviewImageFragment
-        item = menu.findItem(R.id.action_sync_file);
-        if (item != null) {
-            item.setVisible(false);
-            item.setEnabled(false);
-        }
-
-        // additional restriction for this fragment
-        item = menu.findItem(R.id.action_select_all);
-        if (item != null) {
-            item.setVisible(false);
-            item.setEnabled(false);
-        }
-
-        // additional restriction for this fragment
-        item = menu.findItem(R.id.action_move);
-        if (item != null) {
-            item.setVisible(false);
-            item.setEnabled(false);
-        }
-
-        // additional restriction for this fragment
-        item = menu.findItem(R.id.action_copy);
-        if (item != null) {
-            item.setVisible(false);
-            item.setEnabled(false);
-        }
-
-        // additional restriction for this fragment
-        item = menu.findItem(R.id.action_favorite);
-        if (item != null) {
-            item.setVisible(false);
-            item.setEnabled(false);
-        }
-
-        // additional restriction for this fragment
-        item = menu.findItem(R.id.action_unset_favorite);
-        if (item != null) {
-            item.setVisible(false);
-            item.setEnabled(false);
-        }
+        FileMenuFilter.hideMenuItems(
+                menu.findItem(R.id.action_rename_file),
+                menu.findItem(R.id.action_sync_file),
+                menu.findItem(R.id.action_select_all),
+                menu.findItem(R.id.action_move),
+                menu.findItem(R.id.action_copy),
+                menu.findItem(R.id.action_favorite),
+                menu.findItem(R.id.action_unset_favorite)
+        );
 
         if (getFile().isSharedWithMe() && !getFile().canReshare()) {
-            // additional restriction for this fragment
-            item = menu.findItem(R.id.action_send_share_file);
-            if (item != null) {
-                item.setVisible(false);
-                item.setEnabled(false);
-            }
+            FileMenuFilter.hideMenuItem(menu.findItem(R.id.action_send_share_file));
         }
-
     }
 
 

src/main/java/com/owncloud/android/ui/preview/PreviewTextFragment.java

@@ -78,10 +78,10 @@ public class PreviewTextFragment extends FileFragment {
 
     /**
      * Creates an empty fragment for previews.
-     * <p/>
+     *
      * MUST BE KEPT: the system uses it when tries to re-instantiate a fragment automatically
      * (for instance, when the device is turned a aside).
-     * <p/>
+     *
      * DO NOT CALL IT: an {@link OCFile} and {@link Account} must be provided for a successful
      * construction
      */
@@ -169,7 +169,7 @@ public class PreviewTextFragment extends FileFragment {
      * {@inheritDoc}
      */
     @Override
-    public void onSaveInstanceState(Bundle outState) {
+    public void onSaveInstanceState(@NonNull Bundle outState) {
         super.onSaveInstanceState(outState);
         outState.putParcelable(PreviewTextFragment.EXTRA_FILE, getFile());
         outState.putParcelable(PreviewTextFragment.EXTRA_ACCOUNT, mAccount);
@@ -296,82 +296,28 @@ public class PreviewTextFragment extends FileFragment {
         }
 
         // additional restriction for this fragment
-        MenuItem item = menu.findItem(R.id.action_rename_file);
-        if (item != null) {
-            item.setVisible(false);
-            item.setEnabled(false);
-        }
-
-        // additional restriction for this fragment
-        item = menu.findItem(R.id.action_select_all);
-        if (item != null) {
-            item.setVisible(false);
-            item.setEnabled(false);
-        }
-
-        // additional restriction for this fragment
-        item = menu.findItem(R.id.action_move);
-        if (item != null) {
-            item.setVisible(false);
-            item.setEnabled(false);
-        }
-
-        // this one doesn't make sense since the file has to be down in order to be previewed
-        item = menu.findItem(R.id.action_download_file);
-        if (item != null) {
-            item.setVisible(false);
-            item.setEnabled(false);
-        }
-
-        item = menu.findItem(R.id.action_sync_file);
-        if (item != null) {
-            item.setVisible(false);
-            item.setEnabled(false);
-        }
-
-        item = menu.findItem(R.id.action_sync_account);
-        if (item != null) {
-            item.setVisible(false);
-            item.setEnabled(false);
-        }
+        FileMenuFilter.hideMenuItems(
+                menu.findItem(R.id.action_rename_file),
+                menu.findItem(R.id.action_select_all),
+                menu.findItem(R.id.action_move),
+                menu.findItem(R.id.action_download_file),
+                menu.findItem(R.id.action_sync_file),
+                menu.findItem(R.id.action_sync_account),
+                menu.findItem(R.id.action_favorite),
+                menu.findItem(R.id.action_unset_favorite)
+        );
 
         Boolean dualPane = getResources().getBoolean(R.bool.large_land_layout);
 
-        item = menu.findItem(R.id.action_switch_view);
-        if (item != null && !dualPane){
-            item.setVisible(false);
-            item.setEnabled(false);
-        }
-
-        item = menu.findItem(R.id.action_sort);
-        if (item != null && !dualPane) {
-            item.setVisible(false);
-            item.setEnabled(false);
-        }
-
-        // additional restriction for this fragment
-        item = menu.findItem(R.id.action_favorite);
-        if (item != null) {
-            item.setVisible(false);
-            item.setEnabled(false);
-        }
-
-        // additional restriction for this fragment
-        item = menu.findItem(R.id.action_unset_favorite);
-        if (item != null) {
-            item.setVisible(false);
-            item.setEnabled(false);
+        if (!dualPane) {
+            FileMenuFilter.hideMenuItems(menu.findItem(R.id.action_switch_view),
+                    menu.findItem(R.id.action_sort)
+            );
         }
 
         if(getFile().isSharedWithMe() && !getFile().canReshare()){
-            // additional restriction for this fragment
-            item = menu.findItem(R.id.action_send_share_file);
-            if(item != null){
-                item.setVisible(false);
-                item.setEnabled(false);
-            }
+            FileMenuFilter.hideMenuItem(menu.findItem(R.id.action_send_share_file));
         }
-
     }
 
     /**