Fix a bug which causes the ViewModel not retain its state after orientation change.

app/build.gradle

@@ -51,6 +51,8 @@ dependencies {
     def lifecycleVersion = "2.2.0"
     implementation "androidx.lifecycle:lifecycle-livedata:$lifecycleVersion"
     implementation "androidx.lifecycle:lifecycle-viewmodel:$lifecycleVersion"
+    implementation "androidx.lifecycle:lifecycle-runtime:$lifecycleVersion"
+    implementation "androidx.lifecycle:lifecycle-runtime-ktx:$lifecycleVersion"
     implementation "androidx.lifecycle:lifecycle-livedata-ktx:$lifecycleVersion"
     annotationProcessor "androidx.lifecycle:lifecycle-common-java8:$lifecycleVersion"
     implementation 'androidx.paging:paging-runtime:3.0.1'

app/src/main/java/ml/docilealligator/infinityforreddit/activities/Paging3TestActivity.java

@@ -75,6 +75,7 @@ public class Paging3TestActivity extends BaseActivity {
     @Inject
     Executor mExecutor;
     public PostPaging3ViewModel viewModel;
+    private Paging3TestAdapter adapter;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
@@ -103,7 +104,7 @@ public class Paging3TestActivity extends BaseActivity {
         }
 
         RecyclerView recyclerView = findViewById(R.id.recycler_view);
-        Paging3TestAdapter adapter = new Paging3TestAdapter(this, new PostFragment(), mExecutor,
+        adapter = new Paging3TestAdapter(this, new PostFragment(), mExecutor,
                 mOauthRetrofit, mGfycatRetrofit,
                 mRedgifsRetrofit, mCustomThemeWrapper, locale,
                 windowWidth, accessToken, accountName, postType, postLayout, true,
@@ -141,12 +142,14 @@ public class Paging3TestActivity extends BaseActivity {
         });
         recyclerView.setAdapter(adapter);
 
-        viewModel = new ViewModelProvider(this, new PostPaging3ViewModel.Factory(mExecutor, mPaging3Retrofit,
+        viewModel = new ViewModelProvider(this, new PostPaging3ViewModel.Factory(getLifecycle(), mExecutor, mPaging3Retrofit,
                 accessToken, accountName, mSharedPreferences, mPostFeedScrolledPositionSharedPreferences,
                 null, null, null, postType, sortType, null, null,
                 null, null, null)).get(PostPaging3ViewModel.class);
 
-        viewModel.getPosts().observe(this, postPagingData -> adapter.submitData(getLifecycle(), postPagingData));
+        viewModel.getPosts().observe(this, postPagingData -> {
+            adapter.submitData(getLifecycle(), postPagingData);
+        });
     }
 
     @Override

app/src/main/java/ml/docilealligator/infinityforreddit/post/PostPaging3PagingSource.java

@@ -1,6 +1,7 @@
 package ml.docilealligator.infinityforreddit.post;
 
 import android.content.SharedPreferences;
+import android.util.Log;
 
 import androidx.annotation.NonNull;
 import androidx.lifecycle.MutableLiveData;
@@ -76,47 +77,10 @@ public class PostPaging3PagingSource extends ListenableFuturePagingSource<String
         return null;
     }
 
-    /*@Nullable
-    @Override
-    public Object load(@NonNull LoadParams<String> loadParams, @NonNull Continuation<? super LoadResult<String, Post>> continuation) {
-        RedditAPI api = retrofit.create(RedditAPI.class);
-        Call<String> bestPost;
-        if(sortType.getTime() != null) {
-            bestPost = api.getBestPosts(sortType.getType().value, sortType.getTime().value, loadParams.getKey(),
-                    APIUtils.getOAuthHeader(accessToken));
-        } else {
-            bestPost = api.getBestPosts(sortType.getType().value, loadParams.getKey(), APIUtils.getOAuthHeader(accessToken));
-        }
-
-        try {
-            Response<String> response = bestPost.execute();
-            if (response.isSuccessful()) {
-                String responseString = response.body();
-                LinkedHashSet<Post> newPosts = ParsePost.parsePostsSync(responseString, -1, postFilter, readPostList);
-                String lastItem = ParsePost.getLastItem(responseString);
-                if (newPosts == null) {
-                    return new LoadResult.Error<>(new Exception("Error parsing more posts"));
-                } else {
-                    int currentPostsSize = postLinkedHashSet.size();
-                    postLinkedHashSet.addAll(newPosts);
-                    if (currentPostsSize == postLinkedHashSet.size()) {
-                        return new LoadResult.Page<>(new ArrayList<>(), null, lastItem);
-                    } else {
-                        return new LoadResult.Page<>(new ArrayList<>(postLinkedHashSet).subList(currentPostsSize, postLinkedHashSet.size()), null, lastItem);
-                    }
-                }
-            } else {
-                return new LoadResult.Error<>(new Exception("Response failed"));
-            }
-        } catch (IOException e) {
-            e.printStackTrace();
-            return new LoadResult.Error<>(e);
-        }
-    }*/
-
     @NonNull
     @Override
     public ListenableFuture<LoadResult<String, Post>> loadFuture(@NonNull LoadParams<String> loadParams) {
+        Log.i("asfsaf", "s" + loadParams.getKey());
         RedditAPI api = retrofit.create(RedditAPI.class);
         ListenableFuture<Response<String>> bestPost;
         if(sortType.getTime() != null) {

app/src/main/java/ml/docilealligator/infinityforreddit/post/PostPaging3Repository.java

@@ -34,6 +34,7 @@ public class PostPaging3Repository {
     private String userWhere;
     private String multiRedditPath;
     private LinkedHashSet<Post> postLinkedHashSet;
+    private PostPaging3PagingSource paging3PagingSource;
 
     public PostPaging3Repository(Executor executor, Retrofit retrofit, String accessToken, String accountName,
                                  SharedPreferences sharedPreferences,
@@ -57,15 +58,16 @@ public class PostPaging3Repository {
         this.userWhere = userWhere;
         this.multiRedditPath = multiRedditPath;
         this.postLinkedHashSet = postLinkedHashSet;
+        paging3PagingSource = new PostPaging3PagingSource(executor, retrofit, accessToken, accountName, sharedPreferences,
+                postFeedScrolledPositionSharedPreferences, postType, sortType, postFilter, readPostList);
     }
 
     public LiveData<PagingData<Post>> getPostsLiveData() {
-        return PagingLiveData.getLiveData(new Pager<>(new PagingConfig(25, 50, false),
+        Pager<String, Post> pager = new Pager<>(new PagingConfig(25, 25, false), this::returnPagingSoruce);
-                this::returnPagingSoruce));
+        return PagingLiveData.getLiveData(pager);
     }
 
-    private PostPaging3PagingSource returnPagingSoruce() {
+    public PostPaging3PagingSource returnPagingSoruce() {
-        return new PostPaging3PagingSource(executor, retrofit, accessToken, accountName, sharedPreferences,
+        return paging3PagingSource;
-                postFeedScrolledPositionSharedPreferences, postType, sortType, postFilter, readPostList);
     }
 }

app/src/main/java/ml/docilealligator/infinityforreddit/post/PostPaging3ViewModel.java

@@ -3,10 +3,13 @@ package ml.docilealligator.infinityforreddit.post;
 import android.content.SharedPreferences;
 
 import androidx.annotation.NonNull;
+import androidx.lifecycle.Lifecycle;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.ViewModel;
 import androidx.lifecycle.ViewModelKt;
 import androidx.lifecycle.ViewModelProvider;
+import androidx.paging.Pager;
+import androidx.paging.PagingConfig;
 import androidx.paging.PagingData;
 import androidx.paging.PagingLiveData;
 
@@ -23,8 +26,10 @@ public class PostPaging3ViewModel extends ViewModel {
 
     private PostPaging3Repository repository;
     private LiveData<PagingData<Post>> posts;
+    private PostPaging3PagingSource paging3PagingSource;
+    private Lifecycle lifecycle;
 
-    public PostPaging3ViewModel(Executor executor, Retrofit retrofit, String accessToken, String accountName,
+    public PostPaging3ViewModel(Lifecycle lifecycle, Executor executor, Retrofit retrofit, String accessToken, String accountName,
                                 SharedPreferences sharedPreferences,
                                 SharedPreferences postFeedScrolledPositionSharedPreferences,
                                 String subredditOrUserName, String query, String trendingSource, int postType,
@@ -32,14 +37,24 @@ public class PostPaging3ViewModel extends ViewModel {
                                 String userWhere, String multiRedditPath, LinkedHashSet<Post> postLinkedHashSet) {
         repository = new PostPaging3Repository(executor, retrofit, accessToken, accountName, sharedPreferences, postFeedScrolledPositionSharedPreferences,
                 subredditOrUserName, query, trendingSource, postType, sortType, postFilter, readPostList, userWhere, multiRedditPath, postLinkedHashSet);
+        paging3PagingSource = repository.returnPagingSoruce();
+        Pager<String, Post> pager = new Pager<>(new PagingConfig(25, 25, false), this::returnPagingSoruce);
+        posts = PagingLiveData.cachedIn(PagingLiveData.getLiveData(pager), ViewModelKt.getViewModelScope(this));
     }
 
     public LiveData<PagingData<Post>> getPosts() {
-        posts = PagingLiveData.cachedIn(repository.getPostsLiveData(), ViewModelKt.getViewModelScope(this));
+        /*Pager<String, Post> pager = new Pager<>(new PagingConfig(25, 25, false), this::returnPagingSoruce);
+        posts = PagingLiveData.cachedIn(PagingLiveData.getLiveData(pager), ViewModelKt.getViewModelScope(this));
+        posts = PagingLiveData.cachedIn(PagingLiveData.getLiveData(pager), lifecycle);*/
         return posts;
     }
 
+    private PostPaging3PagingSource returnPagingSoruce() {
+        return paging3PagingSource;
+    }
+
     public static class Factory extends ViewModelProvider.NewInstanceFactory {
+        private Lifecycle lifecycle;
         private Executor executor;
         private Retrofit retrofit;
         private String accessToken;
@@ -57,11 +72,12 @@ public class PostPaging3ViewModel extends ViewModel {
         private String multiRedditPath;
         private LinkedHashSet<Post> postLinkedHashSet;
 
-        public Factory(Executor executor, Retrofit retrofit, String accessToken, String accountName, SharedPreferences sharedPreferences,
+        public Factory(Lifecycle lifecycle, Executor executor, Retrofit retrofit, String accessToken, String accountName, SharedPreferences sharedPreferences,
                        SharedPreferences postFeedScrolledPositionSharedPreferences, String subredditOrUserName,
                        String query, String trendingSource, int postType, SortType sortType, PostFilter postFilter,
                        List<ReadPost> readPostList, String userWhere, String multiRedditPath,
                        LinkedHashSet<Post> postLinkedHashSet) {
+            this.lifecycle = lifecycle;
             this.executor = executor;
             this.retrofit = retrofit;
             this.accessToken = accessToken;
@@ -83,7 +99,7 @@ public class PostPaging3ViewModel extends ViewModel {
         @NonNull
         @Override
         public <T extends ViewModel> T create(@NonNull Class<T> modelClass) {
-            return (T) new PostPaging3ViewModel(executor, retrofit, accessToken, accountName, sharedPreferences,
+            return (T) new PostPaging3ViewModel(lifecycle, executor, retrofit, accessToken, accountName, sharedPreferences,
                     postFeedScrolledPositionSharedPreferences, subredditOrUserName, query, trendingSource,
                     postType, sortType, postFilter, readPostList, userWhere, multiRedditPath, postLinkedHashSet);
         }