如何使用StaggeredGridLayoutManager在recyclerview中实现无限滚动（分页）

Question

你好，我有一个 recyclerview，图像是从 firebase 加载的我想实现无限滚动，但我遇到的问题是 StaggeredGridLayoutManager，我必须使用它我无法将其替换为 grid-layout

Note:- I have seen other answers on this topic but the majority of answers are for LinearLayoutManager and some for GridLayout but there is only one answer I found for StaggeredGridLayoutManager which I don't know why it's not working for me

If you want more references of the code please tell me I will update the question

Profile_Fragment.java

 public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_profile, container, false);
    requireActivity().setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
    ImageView accountSettings = view.findViewById(R.id.account_Settings);
    RelativeLayout relativeLayout = view.findViewById(R.id.snipet_profile);
    profilePhoto = relativeLayout.findViewById(R.id.circleImageView);
    editProfileButton = relativeLayout.findViewById(R.id.edit_profile_button);
    uploadImageButton = view.findViewById(R.id.upload_image_profile);
    progressBar = view.findViewById(R.id.progressBar_Profile);
    editProfileButton.setOnClickListener(v -> {
        Fragment edit_profile = new Edit_Profile();
        assert getFragmentManager() != null;
        FragmentTransaction transaction = getFragmentManager().beginTransaction();
        transaction.add(R.id.fragment_container, edit_profile);
        transaction.addToBackStack(String.valueOf(edit_profile));
        transaction.commit();
    });
    uploadImageButton.setOnClickListener(v -> {
        BottomSheet_Upload bottomSheetSettings = new BottomSheet_Upload();
        bottomSheetSettings.show(requireActivity().getSupportFragmentManager(), bottomSheetSettings.getTag());
    });
    accountSettings.setOnClickListener(
            v -> {
                BottomSheet_Settings bottomSheetSettings = new BottomSheet_Settings();
                bottomSheetSettings.show(requireActivity().getSupportFragmentManager(), bottomSheetSettings.getTag());
            }
    );
    postRecyclerView = view.findViewById(R.id.postRecyclerViewProfile);
    StaggeredGridLayoutManager staggeredGridLayoutManager = new StaggeredGridLayoutManager(3, StaggeredGridLayoutManager.VERTICAL);
    postRecyclerView.setLayoutManager(
            staggeredGridLayoutManager // I have 3 rows
    );


    postRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
        @Override
        public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy) {

            visibleItemCount = staggeredGridLayoutManager.getChildCount();
            totalItemCount = staggeredGridLayoutManager.getItemCount();
            int[] firstVisibleItems = null;
            firstVisibleItems = staggeredGridLayoutManager.findFirstVisibleItemPositions(firstVisibleItems);
            if (firstVisibleItems != null && firstVisibleItems.length > 0) {
                pastVisibleItems = firstVisibleItems[0];
            }

            if (loading) {
                if ((visibleItemCount + pastVisibleItems) >= totalItemCount) {
                    loading = false;
                    getData();
                    Log.d("tag", "LOAD NEXT ITEM");
                }
            }
        }
    });
    postRecyclerView.setVisibility(View.INVISIBLE);
    progressBar.setVisibility(View.VISIBLE);
    initImageLoader();
    setProfileImage();
    mUploads = new ArrayList<>();
    postsAdapter = new PostAdapter(getContext(), mUploads);
    postRecyclerView.setAdapter(postsAdapter);
    postsAdapter.setOnItemClickListener(Profile_Fragment.this);
    return view;
}

private void initImageLoader() {
    UniversalImageLoader universalImageLoader = new UniversalImageLoader(getContext());
    ImageLoader.getInstance().init(universalImageLoader.getConfig());
}

private void setProfileImage() {
    String imgUrl = "www.64.media.tumblr.com/1276b4edef49034af70bda14325385e3/d8872c747cafa206-96/s500x750/aa915fc49a84b5295f0cd44145d655b66eb906a6.jpg";
    UniversalImageLoader.setImage(imgUrl, profilePhoto, null, "https://");
}

private void getData() {
    mStorage = FirebaseStorage.getInstance();
    databaseEventListener = databaseReference.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot snapshot) {
            if (snapshot.exists()) {
                progressBar.setVisibility(View.GONE);
                postRecyclerView.setVisibility(View.VISIBLE);
                mUploads.clear();
                for (DataSnapshot dataSnapshot : snapshot.getChildren()) {
                    Upload upload = dataSnapshot.getValue(Upload.class);
                    Objects.requireNonNull(upload).setmKey(dataSnapshot.getKey());
                    mUploads.add(upload);


                }

            }

            //notify the adapter
            postsAdapter.notifyDataSetChanged();
            loading = true;
        }

        @Override
        public void onCancelled(@NonNull DatabaseError error) {
            loading = true;
        }
    });
}

更新 1

主要问题代码已更改为当前答案并根据要求添加了适配器class

问题

实施答案后没有错误，但图像没有加载，所以我用添加的答案更新了主要代码

PostAdapter.java

public class PostAdapter extends RecyclerView.Adapter<PostAdapter.PostViewHolder> {
    public static List<Upload> mUploads;
    public Context mcontext;
    private OnItemClickListener mListener;
    /* ShimmerFrameLayout shimmerFrameLayout; */


    public PostAdapter(Context context, List<Upload> uploads) {
        mUploads = uploads;
        mcontext = context;
    }

    @NonNull
    @Override
    public PostViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view;
        LayoutInflater.from(mcontext).inflate(R.layout.post_item_container_profile, parent, false);
        view = LayoutInflater.from(parent.getContext()).inflate(R.layout.post_item_container_profile, parent, false);
        return new PostViewHolder(view);

    }

    @Override
    public void onBindViewHolder(@NonNull PostViewHolder holder, int position) {
        Upload uploadCurrent = mUploads.get(position);
        Shimmer shimmer = new Shimmer.ColorHighlightBuilder()
                .setBaseColor(Color.parseColor("#F3F3F3"))
                .setBaseAlpha(1)
                .setHighlightColor(Color.parseColor("#E7E7E7"))
                .setHighlightAlpha(1)
                .setDropoff(50)
                .build();
        ShimmerDrawable shimmerDrawable = new ShimmerDrawable();
        shimmerDrawable.setShimmer(shimmer);
        Glide.with(mcontext)
                .load(uploadCurrent.getmImageUrl())
                .diskCacheStrategy(DiskCacheStrategy.AUTOMATIC)
                .placeholder(shimmerDrawable)
                .centerCrop()
                .fitCenter()
                .into(holder.imageView);

    }

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

    public void setOnItemClickListener(OnItemClickListener listener) {
        mListener = listener;

    }

    public interface OnItemClickListener {
        void onClick(View view);

        void onItemClick(int position);

        void onDeleteClick(int position);
    }

    public class PostViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener,
            View.OnCreateContextMenuListener, MenuItem.OnMenuItemClickListener {
        ShapeableImageView imageView;

        PostViewHolder(@NonNull View itemView) {
            super(itemView);
            imageView = itemView.findViewById(R.id.imagePost);

            itemView.setOnClickListener(this);
            itemView.setOnCreateContextMenuListener(this);
        }

        @Override
        public void onClick(View v) {
            if (mListener != null) {
                int position = getAdapterPosition();
                if (position != RecyclerView.NO_POSITION) {
                    mListener.onItemClick(position);
                }
            }
        }

        @Override
        public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) {
            MenuItem delete = menu.add(Menu.NONE, 2, 2, "Delete");
            delete.setOnMenuItemClickListener(this);
        }

        @Override
        public boolean onMenuItemClick(MenuItem item) {
            if (mListener != null) {
                int position = getAdapterPosition();
                if (position != RecyclerView.NO_POSITION) {
                    if (item.getItemId() == 2) {
                        mListener.onDeleteClick(position);
                        return true;
                    }
                }
            }
            return false;
        }
    }
}

Answer 1

对于您的第一个问题，您已经有了解决方案。

StaggeredGridLayoutManager staggeredGridLayoutManager = new 
   StaggeredGridLayoutManager(3, StaggeredGridLayoutManager.VERTICAL);
    postRecyclerView.setLayoutManager(
            staggeredGridLayoutManager // I have 3 rows
    );

第二题：

postRecyclerView.setOnScrollListener(new RecyclerView.OnScrollListener({
    @Override
    public void onScrolled(RecyclerView recyclerView, int dx, int dy) {

        visibleItemCount = staggeredGridLayoutManager .getChildCount();
        totalItemCount = staggeredGridLayoutManager .getItemCount();
        int[] firstVisibleItems = null;
        firstVisibleItems = mLayoutManager.findFirstVisibleItemPositions(firstVisibleItems);
        if(firstVisibleItems != null && firstVisibleItems.length > 0) {
            pastVisibleItems = firstVisibleItems[0];
        }

        if (loading) {
            if ((visibleItemCount + pastVisibleItems) >= totalItemCount) {
                loading = false;
                getData()
            }
        }
    }
 });
 ..........
 ..........
  private void getData() {
    mStorage = FirebaseStorage.getInstance();
    databaseEventListener = databaseReference.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot snapshot) {
            if (snapshot.exists()) {
                progressBar.setVisibility(View.GONE);
                postRecyclerView.setVisibility(View.VISIBLE);
                mUploads.clear();
                for (DataSnapshot dataSnapshot : snapshot.getChildren()) {
                    Upload upload = dataSnapshot.getValue(Upload.class);
                    Objects.requireNonNull(upload).setmKey(dataSnapshot.getKey());
                    mUploads.add(upload);
                }
            }
            //notify the adapter
            postsAdapter.notifyDataSetChanged();
            loading = true;
        }

        @Override
        public void onCancelled(@NonNull DatabaseError error) {
           loading = true;
        }
    });
}

您可能必须首先在 onCreate() 中调用 getData()，以便某些数据加载到屏幕上并且您有滚动行为。

更新： StaggeredGridLayoutManager 中的第二个参数是方向，因此您必须传递方向 StaggeredGridLayoutManager.VERTICAL.

而不是 context

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