导航后未附加回收站视图

Question

我正在使用底部导航视图开发此应用程序。在我的主页片段上，我使用了两个回收器 views.i 正在获取一些数据和图像以显示在主屏幕片段上。在应用程序启动时，图像在两个回收器视图中都可见，但如果我旋转屏幕或导航到其他片段，图像从第二个回收器视图中消失，而第一个回收器视图仍在显示图像。

下面是代码

  public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) { 
 mFavSubCatDatabase = 
 FirebaseDatabase.getInstance().getReference().child("FavSubCat");
    mFavSubCatDatabase.keepSynced(true);
    mFavCatDatabase = 
 FirebaseDatabase.getInstance().getReference().child("FavCat");
    mFavCatDatabase.keepSynced(true);
    //    mLayoutManager = new LinearLayoutManager(getContext());
    RecyclerView.LayoutManager mLayoutManager = new 
 GridLayoutManager(getContext(), 3);
    mFavSubCatList = (RecyclerView) 
    view.findViewById(R.id.HomesubcatOpeningRecler);
    mFavSubCatList.setHasFixedSize(true);
    mFavSubCatList.setLayoutManager(mLayoutManager);
    LinearLayoutManager mLayoutManager2
            = new LinearLayoutManager(getContext(), 
     LinearLayoutManager.HORIZONTAL, false);
    mFavCatList = (RecyclerView) 
    view.findViewById(R.id.HomeCatRecyclerOpening);
    mFavCatList.setHasFixedSize(true);
    mFavCatList.setLayoutManager(mLayoutManager2);
    return view;
   }


@Override
public void onStart() {
    super.onStart();
    startListening();

  }


      public void startListening()
    {



    Query query = FirebaseDatabase.getInstance()
            .getReference()
            .child("FavCat")
            .limitToLast(50);
    FirebaseRecyclerOptions<HomeCatitems> options =
            new FirebaseRecyclerOptions.Builder<HomeCatitems>()
                    .setQuery(query, HomeCatitems.class)
                    .build();
    FirebaseRecyclerAdapter adapter = new 
    FirebaseRecyclerAdapter<HomeCatitems, CategoryViewHolder>(options) {
        @Override
        public CategoryViewHolder onCreateViewHolder(ViewGroup parent, int 
    viewType) {              
            View view = LayoutInflater.from(parent.getContext())
                    .inflate(R.layout.home_cat_layout, parent, false);
            return new CategoryViewHolder(view);
        }
        @Override
        protected void onBindViewHolder(final CategoryViewHolder holder, int 
     position, final HomeCatitems model) {
            holder.setDisplayName(model.getName());
            holder.setUserImage(model.getImageUrl(), getContext());

        }
    };
    mFavCatList.setAdapter(adapter);
    adapter.startListening();






    Query query1 = FirebaseDatabase.getInstance()
            .getReference()
            .child("FavSubCat")
            .limitToLast(50);

    FirebaseRecyclerOptions<CategoryItems> options1 =
            new FirebaseRecyclerOptions.Builder<CategoryItems>()
                    .setQuery(query1, CategoryItems.class)
                    .build();



    FirebaseRecyclerAdapter adaptersubcat = new 
    FirebaseRecyclerAdapter<CategoryItems, SubCategoryViewHolder>(options1)  
    {
        @Override
        public SubCategoryViewHolder onCreateViewHolder(ViewGroup parent, 
    int viewType) {

            View view = LayoutInflater.from(parent.getContext())
                    .inflate(R.layout.home_subcat_items, parent, false);
            return new SubCategoryViewHolder(view);
        }

        @Override
        protected void onBindViewHolder(final SubCategoryViewHolder holder, 
     int position, final CategoryItems model) {

            holder.setDisplayName(model.getName());
            holder.setUserImage(model.getImageUrl(), getContext());


        }
    };
    mFavSubCatList.setAdapter(adaptersubcat);
    adaptersubcat.startListening();
    }

其中一个内部viewHolder class如下所示 public 静态 class SubCategoryViewHolder 扩展 RecyclerView.ViewHolder {

    View mView;
    ImageView subcategoryImageView;
    TextView subcategoryName;

    public SubCategoryViewHolder(View itemView) {
        super(itemView);

        mView = itemView;

    }

    public void setDisplayName(String name){

        subcategoryName = (TextView) 
    mView.findViewById(R.id.home_subcat_name);
        subcategoryName.setText(name);


    }


    public void setUserImage(final String thumb_image, final Context ctx){

        subcategoryImageView = (ImageView) 
   mView.findViewById(R.id.home_subcat_image);
        Picasso.with(ctx).setIndicatorsEnabled(false);

    Picasso.with(ctx).load(thumb_image).networkPolicy(NetworkPolicy.OFFLINE)

    .placeholder(R.drawable.default_avatar).into(subcategoryImageView, new 
    Callback() {
            @Override
            public void onSuccess() {

            }

            @Override
            public void onError() {



 Picasso.with(ctx).load(thumb_image).placeholder(R.drawable.default_avatar)
       .into(subcategoryImageView);

            }
        });

    }



}

Answer 1

尝试使用onResume方法在旋转后再次将图像设置到图像视图中。或者只使用 onSavedInstanceState 并将图像重新分配到 imageview 中，如这个问题中所回答的：ImageView not retaining Image when Screen rotation occurs

Answer 2

正如我在评论中提到的，这似乎与 ViewHolder 实现或 Picasso 的缓存有关。您的代码中最可疑的一点是：

Picasso.with(ctx).load(thumb_image).networkPolicy(NetworkPolicy.OFFLINE);

您可能想删除那里的网络策略声明，是否有理由让您首先使用错误回调来加载图像？ Picasso 会自动为您执行此操作（如果无法从网络获取，则从 memory/disk 缓存中获取）。尝试删除它并仅使用以下方式加载图像：

Picasso.with(ctx).load(thumb_image).placeholder(R.drawable.default_avatar).into(subcategoryImageView);

编辑：另外，如果您需要更多信息，这里是 NetworkPolicy 的文档：https://square.github.io/picasso/2.x/picasso/com/squareup/picasso/NetworkPolicy.html.

Answer 3

经过大量搜索后，我发现我正在使用 setHasFixedSize(true) 和 wrap_content 回收站视图。我删除了 setHasFixedSize(true)，它现在工作得很好。

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