Fix memory leaks and add documentation

app/src/main/java/org/schabi/newpipe/BaseFragment.java

@@ -80,9 +80,29 @@ protected void onRestoreInstanceState(@NonNull final Bundle savedInstanceState)
     // Init
     //////////////////////////////////////////////////////////////////////////*/
 
+    /**
+     * This method is called in {@link #onViewCreated(View, Bundle)} to initialize the views.
+     *
+     * <p>
+     * {@link #initListeners()} is called after this method to initialize the corresponding
+     * listeners.
+     * </p>
+     * @param rootView The inflated view for this fragment
+     *                 (provided by {@link #onViewCreated(View, Bundle)})
+     * @param savedInstanceState The saved state of this fragment
+ *                               (provided by {@link #onViewCreated(View, Bundle)})
+     */
     protected void initViews(final View rootView, final Bundle savedInstanceState) {
     }
 
+    /**
+     * Initialize the listeners for this fragment.
+     *
+     * <p>
+     * This method is called after {@link #initViews(View, Bundle)}
+     * in {@link #onViewCreated(View, Bundle)}.
+     * </p>
+     */
     protected void initListeners() {
     }
 

app/src/main/java/org/schabi/newpipe/fragments/BaseStateFragment.java

@@ -80,6 +80,8 @@ public void onDestroyView() {
         if (errorPanelHelper != null) {
             errorPanelHelper.dispose();
         }
+        emptyStateView = null;
+        emptyStateMessageView = null;
     }
 
     protected void onRetryButtonClicked() {

app/src/main/java/org/schabi/newpipe/fragments/MainFragment.java

@@ -139,6 +139,12 @@ public void onDestroy() {
         }
     }
 
+    @Override
+    public void onDestroyView() {
+        super.onDestroyView();
+        binding = null;
+    }
+
     /*//////////////////////////////////////////////////////////////////////////
     // Menu
     //////////////////////////////////////////////////////////////////////////*/

app/src/main/java/org/schabi/newpipe/local/subscription/SubscriptionFragment.kt

@@ -115,6 +115,11 @@ class SubscriptionFragment : BaseStateFragment<SubscriptionState>() {
         feedGroupsCarouselState = feedGroupsCarousel.onSaveInstanceState()
     }
 
+    override fun onDestroyView() {
+        super.onDestroyView()
+        _binding = null
+    }
+
     override fun onDestroy() {
         super.onDestroy()
         disposables.dispose()