RecyclerView中的ImageView

Question

在我MainActivity.java我有一个登录按钮。我还有4个片段，每个片段都包含一个回收站视图（imageview + textview）。 图像视图被隐藏，但是当我按下按钮时它变得可见。我怎样才能做到这一点？ notifyDataSetChanged()在适配器中不起作用，我无法在片段页面中的适配器上调用它，因为它不在onCreateView方法之内。 这是我的代码：

MainActivity：包含按钮

片段页面：

public class Classici_Tab extends Fragment {

    LinkedList<Book> catalog = new LinkedList<>();

    RecyclerView mRecyclerView;
    BookListAdapter mAdapter;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View fragmentView = inflater.inflate(R.layout.classici_tab, container, false);

        fillCatalog("catalog.csv");     //fill the LinkedList

        mRecyclerView = (RecyclerView) fragmentView.findViewById(R.id.classici_rv);
        mAdapter = new BookListAdapter(getContext(), catalog);
        mRecyclerView.setAdapter(mAdapter);
        mRecyclerView.setLayoutManager(new LinearLayoutManager(getContext()));

        return fragmentView;
    }
}

适配器：

public class BookListAdapter extends RecyclerView.Adapter<BookListAdapter.BookViewHolder> {

    // View Holder
    class BookViewHolder extends RecyclerView.ViewHolder
    {
        public final ImageView cover;
        public final TextView title;
        public final TextView author;
        public final ImageView availability;
        final BookListAdapter mAdapter;

        public BookViewHolder(View itemView, BookListAdapter adapter) {
            super(itemView);
            cover = (ImageView) itemView.findViewById(R.id.cover);
            title = (TextView) itemView.findViewById(R.id.title);
            author = (TextView) itemView.findViewById(R.id.author);
            availability = (ImageView) itemView.findViewById(R.id.availability);

            MainActivity m = new MainActivity();
            if(m.loggedin)  availability.setVisibility(View.VISIBLE);
            else            availability.setVisibility(View.INVISIBLE);

            this.mAdapter = adapter;
        }
    }

    private LinkedList<Book> mBookList = new LinkedList<>();
    private LayoutInflater mInflater;
    boolean isVisible = false;

    public BookListAdapter()    {}

    public BookListAdapter(Context context, LinkedList<Book> bookList) {
        mInflater = LayoutInflater.from(context);
        this.mBookList = bookList;
    }

    //IT DOESN'T WORK
    public void setPicturesVisibility(boolean isVisible){
        this.isVisible = true;
        notifyDataSetChanged();
    }

    @Override
    public BookViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View mItemView = mInflater.inflate(R.layout.tab_list_item, parent, false);
        return new BookViewHolder(mItemView, this);
    }

    @Override
    public void onBindViewHolder(BookViewHolder holder, int position) {
        holder.cover.setImageResource(mBookList.get(position).getCover());
        holder.title.setText(mBookList.get(position).getTitle());
        holder.author.setText(mBookList.get(position).getAuthor());
        holder.availability.setImageResource(mBookList.get(position).getAvailability());

        if(isVisible){
            holder.availability.setVisibility(View.VISIBLE);
        }else{
            holder.availability.setVisibility(View.INVISIBLE);
        }
    }

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

Answer 1

无需重新创建适配器。您可以在RecyclerViewAdapter中添加布尔值arePicturesVisible = false;。 并在适配器中创建一个方法：

public void setPicturesVisibility(boolean areVisible){
    arePicturesVisible = areVisible;
    notifyDataSetChanged();
}

然后添加：

@Override
public void onBindViewHolder(MyViewHolder holder, int position) {
    .....
    if(arePicturesVisible){
        holder.image.setVisibility(View.VISIBLE);
    }else{
        holder.image.setVisibility(View.INVISIBLE);
    }
    .....
}

然后在您的按钮onClick()方法中，从RecyclerView适配器调用setPicturesVisibility()。

Answer 2

不确定为什么需要重新创建适配器。在不重新创建适配器的情况下，您可以向按钮添加侦听器，并在onclick事件处理程序中，使图像在recyclerview适配器的视图构造器中可见。

public ViewHolder(View view) {
        super(view);
        textview = view.findViewById(R.id.textview);       
        imgView = view.findViewById(R.id.storeImg);

        Button button = (Button) view.findViewById(R.id.button);

        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
            imgView.setVisibility(View.VISIBLE);
            }
        });
    }

您可以在http://www.zoftino.com/android

找到recyclerview示例