EndlessRecyclerViewScrollListener does not show all items on recyclerview

Issue

I have 24 rows in database from 1 to 24 but the problem with EndlessRecyclerViewScrollListener class when I try show Items on recyclerview become shuffle items.

I want show Items from #1 to #24

PostsActivity

public class PostsActivity extends AppCompatActivity {

    @BindView(R.id.rv_posts)
    RecyclerView rv_posts;
    SaveSystem saveSystem;
    List<PostsModels> postsModels = new ArrayList<>();
    PostsAdapter postsAdapter;
    EndlessRecyclerViewScrollListener scrollListener;
    int page = 0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_posts);
        ButterKnife.bind(this);
        saveSystem = new SaveSystem(this);
        //check first time
        if (saveSystem.LoadBooleanData("FirstTime")) {
            saveSystem.SaveStringData("language", "en");
            saveSystem.SaveBooleanData("FirstTime", false);
        }
        //setData
        setData();
    }

    void setData() {
        postsAdapter = new PostsAdapter(PostsActivity.this, postsModels);
        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(PostsActivity.this, LinearLayoutManager.VERTICAL, false);
        rv_posts.setLayoutManager(linearLayoutManager);
        rv_posts.setAdapter(postsAdapter);
        scrollListener = new EndlessRecyclerViewScrollListener(linearLayoutManager) {
            @Override
            public void onLoadMore(int i, int totalItemsCount, RecyclerView view) {
                page = page + 10;
                Toast.makeText(PostsActivity.this, "" + page, Toast.LENGTH_SHORT).show();
                retrofit(page);
            }
        };
        rv_posts.addOnScrollListener(scrollListener);
        retrofit(page);
    }

    void retrofit(int number) {
        Retrofit retrofit = new Retrofit.Builder().baseUrl("http://***").addConverterFactory(GsonConverterFactory.create()).build();
        HTTP http = retrofit.create(HTTP.class);
        Call<List<PostsModels>> call = http.get_posts(saveSystem.LoadStringData("language"), number);
        call.enqueue(new Callback<List<PostsModels>>() {
            @Override
            public void onResponse(Call<List<PostsModels>> call, Response<List<PostsModels>> response) {
                List<PostsModels> list = response.body();
                for (PostsModels i : list) {
                    postsModels.add(new PostsModels(i.id, i.user_id, i.user_name, i.word, i.description, i.sound, i.level, i.shortcut));
                }
                postsAdapter.notifyItemRangeInserted(postsAdapter.getItemCount(), list.size() - 1);
            }

            @Override
            public void onFailure(Call<List<PostsModels>> call, Throwable t) {

            }
        });
    }

}

PostsModels

public class PostsModels {

    @SerializedName("id")
    String id;
    @SerializedName("user_id")
    String user_id;
    @SerializedName("user_name")
    String user_name;
    @SerializedName("word")
    String word;
    @SerializedName("description")
    String description;
    @SerializedName("sound")
    String sound;
    @SerializedName("level")
    String level;
    @SerializedName("shortcut")
    String shortcut;

    public PostsModels(String id, String user_id, String user_name, String word, String description, String sound, String level, String shortcut) {
        this.id = id;
        this.user_id = user_id;
        this.user_name = user_name;
        this.word = word;
        this.description = description;
        this.sound = sound;
        this.level = level;
        this.shortcut = shortcut;
    }
}

PostsAdapter

public class PostsAdapter extends RecyclerView.Adapter<PostsAdapter.posts> {

    Context context;
    List<PostsModels> postsModels;
    int lastCheckedPosition = -1;

    public PostsAdapter(Context context, List<PostsModels> postsModels) {
        this.context = context;
        this.postsModels = postsModels;
    }

    @NonNull
    @Override
    public posts onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
        View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.row_posts, viewGroup, false);
        posts viewHolder = new posts(view);
        return viewHolder;
    }

    @Override
    public void onBindViewHolder(@NonNull posts posts, int i) {
        PostsModels list = postsModels.get(i);
        //set photo
        Picasso.get().load("http://graph.facebook.com/" + list.user_id + "/picture?type=large").into(posts.img_profile);
        //set word
        posts.txt_word.setText(list.word);
        //set id
        posts.txt_id.setText("#" + list.id);
        //set description
        posts.txt_description.setText(list.description);
        //if checked
        if (lastCheckedPosition == i) {
            posts.linear_layout.setBackgroundColor(context.getResources().getColor(R.color.posts_item_selected_1));
            posts.frame_pink.setVisibility(View.VISIBLE);
        } else {
            posts.linear_layout.setBackgroundColor(0x000000000);
            posts.frame_pink.setVisibility(View.INVISIBLE);
        }
    }

    @Override
    public int getItemCount() {
        return postsModels.size();
    }

    class posts extends RecyclerView.ViewHolder {

        @BindView(R.id.linear_layout)
        LinearLayout linear_layout;
        @BindView(R.id.frame_pink)
        FrameLayout frame_pink;
        @BindView(R.id.img_profile)
        CircleImageView img_profile;
        @BindView(R.id.txt_word)
        TextViewFont txt_word;
        @BindView(R.id.txt_id)
        TextViewFont txt_id;
        @BindView(R.id.txt_description)
        TextViewFont txt_description;

        @OnClick(R.id.linear_layout)
        public void onClick() {
            lastCheckedPosition = getAdapterPosition();
            notifyDataSetChanged();
        }

        public posts(View view) {
            super(view);
            ButterKnife.bind(this, view);
        }

    }
}

EndlessRecyclerViewScrollListener

public abstract class EndlessRecyclerViewScrollListener extends RecyclerView.OnScrollListener {
    // The minimum amount of items to have below your current scroll position
    //    // before loading more.
    private int visibleThreshold = 5;
    // The current offset index of data you have loaded
    private int currentPage = 0;
    // The total number of items in the dataset after the last load
    private int previousTotalItemCount = 0;
    // True if we are still waiting for the last set of data to load.
    private boolean loading = true;
    // Sets the starting page index
    private int startingPageIndex = 0;

    RecyclerView.LayoutManager mLayoutManager;

    public EndlessRecyclerViewScrollListener(LinearLayoutManager layoutManager) {
        this.mLayoutManager = layoutManager;
    }

    public EndlessRecyclerViewScrollListener(GridLayoutManager layoutManager) {
        this.mLayoutManager = layoutManager;
        visibleThreshold = visibleThreshold * layoutManager.getSpanCount();
    }

    public EndlessRecyclerViewScrollListener(StaggeredGridLayoutManager layoutManager) {
        this.mLayoutManager = layoutManager;
        visibleThreshold = visibleThreshold * layoutManager.getSpanCount();
    }

    public int getLastVisibleItem(int[] lastVisibleItemPositions) {
        int maxSize = 0;
        for (int i = 0; i < lastVisibleItemPositions.length; i++) {
            if (i == 0) {
                maxSize = lastVisibleItemPositions[i];
            }
            else if (lastVisibleItemPositions[i] > maxSize) {
                maxSize = lastVisibleItemPositions[i];
            }
        }
        return maxSize;
    }

    // This happens many times a second during a scroll, so be wary of the code you place here.
    // We are given a few useful parameters to help us work out if we need to load some more data,
    // but first we check if we are waiting for the previous load to finish.
    @Override
    public void onScrolled(RecyclerView view, int dx, int dy) {
        int lastVisibleItemPosition = 0;
        int totalItemCount = mLayoutManager.getItemCount();

        if (mLayoutManager instanceof StaggeredGridLayoutManager) {
            int[] lastVisibleItemPositions = ((StaggeredGridLayoutManager) mLayoutManager).findLastVisibleItemPositions(null);
            // get maximum element within the list
            lastVisibleItemPosition = getLastVisibleItem(lastVisibleItemPositions);
        } else if (mLayoutManager instanceof GridLayoutManager) {
            lastVisibleItemPosition = ((GridLayoutManager) mLayoutManager).findLastVisibleItemPosition();
        } else if (mLayoutManager instanceof LinearLayoutManager) {
            lastVisibleItemPosition = ((LinearLayoutManager) mLayoutManager).findLastVisibleItemPosition();
        }

        // If the total item count is zero and the previous isn't, assume the
        // list is invalidated and should be reset back to initial state
        if (totalItemCount < previousTotalItemCount) {
            this.currentPage = this.startingPageIndex;
            this.previousTotalItemCount = totalItemCount;
            if (totalItemCount == 0) {
                this.loading = true;
            }
        }
        // If it’s still loading, we check to see if the dataset count has
        // changed, if so we conclude it has finished loading and update the current page
        // number and total item count.
        if (loading && (totalItemCount > previousTotalItemCount)) {
            loading = false;
            previousTotalItemCount = totalItemCount;
        }

        // If it isn’t currently loading, we check to see if we have breached
        // the visibleThreshold and need to reload more data.
        // If we do need to reload some more data, we execute onLoadMore to fetch the data.
        // threshold should reflect how many total columns there are too
        if (!loading && (lastVisibleItemPosition + visibleThreshold) > totalItemCount) {
            currentPage++;
            onLoadMore(currentPage, totalItemCount, view);
            loading = true;
        }
    }

    // Call this method whenever performing new searches
    public void resetState() {
        this.currentPage = this.startingPageIndex;
        this.previousTotalItemCount = 0;
        this.loading = true;
    }

    // Defines the process for actually loading more data based on page
    public abstract void onLoadMore(int page, int totalItemsCount, RecyclerView view);

I hope you help me to found solution....

Solution

EndlessRecyclerViewScrollListener checks the last visible position with the LayoutManager. When it detects the final one (in this case), call onLoadMore() method. Something weird I notice is that you are managing page in the activity but then ignoring the currentPage value that is using the listener.

Maybe the problem is in that difference. Put a breakpoint inside the EndlessRecyclerViewScrollListener and check how many times calls ´onLoadMore()` method and with which parameters.

Hope it helps.

Answered By - Juanje