每次都会在Recyclerview Adapter中创建Viewpager适配器

Question

我有一个ViewPager里面的RecyclerView适配器来显示多个图像。

 @Override
public void onBindViewHolder(@NonNull final RecyclerView.ViewHolder holder, final int position) {

   Call<List<ImagesModel>> call = restApiClass.getPostImages(list.get(position).getId());
    call.enqueue(new Callback<List<ImagesModel>>() {
        @Override
        public void onResponse(Call<List<ImagesModel>> call, Response<List<ImagesModel>> response) {

            if (response.isSuccessful() && response.body() != null) {

                imagesList = response.body();

                viewPagerAdapter = new ViewPagerAdapter (imagesList, context);
                Log.i("adapterPosts", "A NEW ADAPTER IS CREATED");

                holder.postsViewPager.setAdapter(viewPagerAdapter );
                holder.postsCircleIndicator.setViewPager(holder.postsViewPager);

            }
        }
}

ViewPager适配器：

@NonNull
@Override
public Object instantiateItem(@NonNull ViewGroup container, int position) {

   //...defination codes...//
    progressBar .setVisibility(View.VISIBLE);

    Glide.with(context).load(ApiClient.Base_URL + list.get(position).getImage())
            .diskCacheStrategy(DiskCacheStrategy.RESOURCE)
            .dontAnimate()
            .dontTransform()
            .fitCenter()
            .listener(new RequestListener<Drawable>() {
                @Override
                public boolean onLoadFailed(@Nullable GlideException e, Object model, Target<Drawable> target, boolean isFirstResource) {
                    progressBar .setVisibility(View.GONE);
                    return false;
                }

                @Override
                public boolean onResourceReady(Drawable resource, Object model, Target<Drawable> target, DataSource dataSource, boolean isFirstResource) {
                    progressBar .setVisibility(View.GONE);
                    return false;
                }
            })
            .into(photoView);

    container.addView(view);
    return view;
}

问题：当我上下滚动回收站视图时，ViewPager适配器会被一遍又一遍地创建，即使它是以前创建的（我在日志中看到它）。我知道每次都调用onBindViewHolder（），所以我尝试了这个：

    if(viewPagerAdapter ==null){
                viewPagerAdapter = new ViewPagerAdapter(imagesList, context);
                holder.postsViewPager.setAdapter(viewPagerAdapter);
             holder.postsCircleIndicator.setViewPager(holder.postsViewPager);
    } else {
     viewPagerAdapter.notifyDataSetChanced();
    }

但这一次只加载了第一个ViewPager。那么，我必须做些什么来避免每次创建适配器呢？

Answer 1

看，似乎您试图对每个项目使用相同的适配器作为全局字段，尝试使适配器成为每个视图持有者类的成员字段，如下所示：

public static class YourViewHolder extends RecyclerView.ViewHolder {
    ............
    private ViewPagerAdapter adapter;
    ..........

    public YourViewHolder(View v) {
        super(v);

        ................



    }

在onBindViewHolder中：

  @Override
  public void onBindViewHolder(@NonNull final RecyclerView.ViewHolder holder, final int position) {

          .....................

        if (response.isSuccessful() && response.body() != null) {

            ...........

            imagesList = response.body();

            //create the adapter per viewholder if not exists
            if(holder.adapter==null){

            //create adapter
            holder.adapter = new ViewPagerAdapter (imagesList, context);

            //set adapter
            holder.postsViewPager.setAdapter(holder.adapter);

             }



            .........

        }
    }
  }