Recycler 视图 Onclick 打开对话框，在卡片视图中显示数据

Question

I'm trying to implement Onclick on my RecyclerView . I tried many ways of doing it, but it ends up crashing my application. I also would like to have a dialog when any of the cardView is clicked.

I'm using fireBase as my backend, and I'm quite new to this.

Here's my Adapter class:

public class BlogRecyclerAdapter extends RecyclerView.Adapter<BlogRecyclerAdapter.ViewHolder> {
    public List<BlogPost>blogList;
    public Context context;
    private FirebaseFirestore firebaseFirestore;

    private static final int SECOND_MILLIS = 1000;
    private static final int MINUTE_MILLIS = 60 * SECOND_MILLIS;
    private static final int HOUR_MILLIS = 60 * MINUTE_MILLIS;
    private static final int DAY_MILLIS = 24 * HOUR_MILLIS;
    String dateString;

    public  BlogRecyclerAdapter(List<BlogPost>blogList){
        this.blogList=blogList;
    }

    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull final ViewGroup parent, int viewType) {
        View view= LayoutInflater.from(parent.getContext()).inflate(R.layout.blog_list_item,parent,false);
        context=parent.getContext();
        firebaseFirestore=FirebaseFirestore.getInstance();
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull final ViewHolder holder, int position) {
        String descData=blogList.get(position).getDesc();
        holder.setDescText(descData);
        String imageUrl=blogList.get(position).getImage_url();
        holder.setBlogImage(imageUrl);
        final String userId=blogList.get(position).getUser_id();
        firebaseFirestore.collection("Users").document(userId).get().addOnCompleteListener(new OnCompleteListener<DocumentSnapshot>() {
            @Override
            public void onComplete(@NonNull Task<DocumentSnapshot> task) {
                if(task.isSuccessful()){
                    String username=task.getResult().getString("Name");
                    holder.setUserData(username);
                }
                else{

                }
            }
        });

        long miliseconds=blogList.get(position).getTimestamp().getTime();
        long now = System.currentTimeMillis();

        final long diff = now - miliseconds;
        if (diff < MINUTE_MILLIS) {
             dateString= "just now";
        } else if (diff < 2 * MINUTE_MILLIS) {
             dateString= "a minute ago";
        } else if (diff < 50 * MINUTE_MILLIS) {
             dateString= diff / MINUTE_MILLIS + " minutes ago";
        } else if (diff < 90 * MINUTE_MILLIS) {
             dateString= "an hour ago";
        } else if (diff < 24 * HOUR_MILLIS) {
             dateString= diff / HOUR_MILLIS + " hours ago";
        } else if (diff < 48 * HOUR_MILLIS) {
             dateString= "yesterday";
        } else {
             dateString= diff / DAY_MILLIS + " days ago";
        }
        // String dateString= DateFormat.format("MM/dd/yyyy",new Date(miliseconds)).toString();
        holder.setTime(dateString);
    }

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

    public class ViewHolder extends RecyclerView.ViewHolder{
        private View mView;
        private TextView descView;
        private ImageView blogImageView;
        private TextView blogDate;
        private TextView blogUserName;

        public ViewHolder(@NonNull View itemView) {
            super(itemView);
            mView=itemView;
        }

        public void setUserData(String name){
            blogUserName=mView.findViewById(R.id.blogUserName);
            blogUserName.setText(name);
        }

        public void setDescText(String descText){
            descView=mView.findViewById(R.id.blogDesc);
            descView.setText(descText);
        }

        public void setBlogImage(String downloaduri){
            blogImageView=mView.findViewById(R.id.blogImage);
            Glide.with(context).load(downloaduri).apply(RequestOptions.bitmapTransform(new BlurTransformation(30,3))).into(blogImageView);
        }

        public void setTime(String date){
            blogDate=mView.findViewById(R.id.blogDate);
            blogDate.setText(date);
        }
    }
}

I tried many methods of implementing, it but was unsuccessful.

Answer 1

Adding onClickListener to RecyclerView is a painful process than ListView. But there is a way to do it.

1. Firstly, add this class to your adapter.

    public static class RecyclerItemClickListener implements RecyclerView.OnItemTouchListener { private OnItemClickListener mListener; public interface OnItemClickListener { public void onItemClick(View view, int position); public void onLongItemClick(View view, int position); } GestureDetector mGestureDetector; public RecyclerItemClickListener(Context context, final RecyclerView recyclerView, OnItemClickListener listener) { mListener = listener; mGestureDetector = new GestureDetector(context, new GestureDetector.SimpleOnGestureListener() { @Override public boolean onSingleTapUp(MotionEvent e) { return true; } @Override public void onLongPress(MotionEvent e) { View child = recyclerView.findChildViewUnder(e.getX(), e.getY()); if (child != null && mListener != null) { mListener.onLongItemClick(child, recyclerView.getChildAdapterPosition(child)); } } }); } @Override public boolean onInterceptTouchEvent(RecyclerView view, MotionEvent e) { View childView = view.findChildViewUnder(e.getX(), e.getY()); if (childView != null && mListener != null && mGestureDetector.onTouchEvent(e)) { mListener.onItemClick(childView, view.getChildAdapterPosition(childView)); return true; } return false; } @Override public void onTouchEvent(RecyclerView view, MotionEvent motionEvent) { } @Override public void onRequestDisallowInterceptTouchEvent (boolean disallowIntercept){} } 

2. Secondly, add this listener to your activity/fragment

    recyclerView.addOnItemTouchListener(new BlogRecyclerAdapter.RecyclerItemClickListener(getActivity(), recyclerView ,new BlogRecyclerAdapter.RecyclerItemClickListener.OnItemClickListener() { @Override public void onItemClick(View view, int position) { // Do something here... } @Override public void onLongItemClick(View view, int position) { } }) ); 

Answer 2

First of all, to apply ClickListeners to items(cardviews), because RecyclerView doesnt have default ones, you need to do the following:

1. Define public interface inside your adapter with functions u need(ex: OnClick())
2. Implement that interface in your activity
3. Modify your adapters constructor so it receives instance of that interface( your activity coz its implementing it) and declare member variable listener of type of interface you declared
4. Pass that your activity as an argument when initializing adapter ex. adapter = BlogrecyclerAdapter(this) 5.Make your your blog_list_item clickable in xml 6.set clickListener to you items rootview holder.itemview.setOnClickListener((View)-> listener.OnClick())
   5. You can pass some arguments to OnClick if u need