滚动提要时,RecyclerView跳转到顶部

Question

我正在做一个西班牙新闻应用程序，看这里：

这个应用程序的问题是，每当任何用户点击like、play audio或translate按钮时，recyclerView就会跳到顶部。

>

数据以片段形式从Firebase实时数据库中获取。请帮帮忙。

@override public View onCreateView（LayoutInfluater Influater,ViewGroup container,Bundle savedInstanceState）{//为此片段充气mView=inflater.Inflate（r.layout.fragment_feed,container,false）；

    MobileAds.initialize(mView.getContext(), "XXXXXXXXX");


    mRewardedVideoAd = MobileAds.getRewardedVideoAdInstance(mView.getContext());
    mRewardedVideoAd.setRewardedVideoAdListener(this);
    loadRewardedVideoAd();

    mAuth = FirebaseAuth.getInstance();

    feedRecycler = mView.findViewById(R.id.recycler_feed);
    feedRecycler.setLayoutManager(new LinearLayoutManager(getContext()));
    RecyclerView.Adapter adapter = new FeedAdapter(mView.getContext(),mRecyclerViewItems);
    feedRecycler.setAdapter(adapter);

    userImage = mView.findViewById(R.id.feed_img);
    username = mView.findViewById(R.id.feed_name);
    usercomment = mView.findViewById(R.id.feed_edittext);
    subMitComment = mView.findViewById(R.id.feed_submit);


    mUSerCmt = FirebaseDatabase.getInstance().getReference().child("feeds");
    mScoreRef = FirebaseDatabase.getInstance().getReference().child("scores");

    if(mAuth.getCurrentUser().getPhotoUrl()!= null) {

        Picasso.get().load(mAuth.getCurrentUser().getPhotoUrl().toString()).into(userImage);
        username.setText(mAuth.getCurrentUser().getDisplayName());

    } else {

        startActivity(new Intent(mView.getContext(),UserProfile.class));

    }

    subMitComment.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            String usercmt = usercomment.getText().toString();

            if(!usercmt.equals("")){

                writeNewPost(usercmt,mAuth.getUid(),mAuth.getCurrentUser().getDisplayName(),mAuth.getCurrentUser().getPhotoUrl().toString());

                Toast.makeText(mView.getContext(),"Comment updated!",Toast.LENGTH_SHORT).show();

            }

            usercomment.setText("");


        }
    });

    mUSerCmt.orderByChild("timestamp").addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
            mRecyclerViewItems.clear();
            for (DataSnapshot dataSnapshot1 : dataSnapshot.getChildren()) {
                Model_Feed epiModel = dataSnapshot1.getValue(Model_Feed.class);
                mRecyclerViewItems.add(epiModel);
            }
            FeedAdapter = new FeedAdapter(mView.getContext(), mRecyclerViewItems);
            feedRecycler.setAdapter(FeedAdapter);
            FeedAdapter.notifyDataSetChanged();



        }

        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {

        }
    });




    return mView;
}

private void writeNewPost(String sen, String uid, String name, String img) {
    // Create new post at /user-posts/$userid/$postid and at
    // /posts/$postid simultaneously
    String key = mUSerCmt.push().getKey();
    long time = System.currentTimeMillis() * (-1);
    Model_Feed post = new Model_Feed(sen,time,uid, name, img,key);
    Map<String, Object> postValues = post.toMap();

    Map<String, Object> childUpdates = new HashMap<>();
    childUpdates.put(key, postValues);


    mUSerCmt.updateChildren(childUpdates);
}

public class FeedAdapter extends RecyclerView.Adapter<FeedAdapter.FeedViewHolder>{

    private Context context;
    private List<Object> mRecyclerViewItems;

    public FeedAdapter(Context context, List<Object> mRecyclerViewItems) {
        this.context = context;
        this.mRecyclerViewItems = mRecyclerViewItems;
    }

    @NonNull
    @Override
    public FeedViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
        LayoutInflater inflater = LayoutInflater.from(context);
        View view = inflater.inflate(R.layout.rec_words,viewGroup,false);
        return new FeedViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull final FeedViewHolder feedViewHolder, int i) {

        final Model_Feed modelFeed = (Model_Feed) mRecyclerViewItems.get(i);

        Picasso.get().load(modelFeed.getImg()).into(feedViewHolder.circleImageView);
        feedViewHolder.nameWord.setText(modelFeed.getName());
        feedViewHolder.statusword.setText(modelFeed.getSen());
        feedViewHolder.fireword.setText(String.valueOf(modelFeed.fires.size()));
        feedViewHolder.playword.setText(String.valueOf(modelFeed.plays.size()));

        if(modelFeed.fires.containsKey(mAuth.getUid())){
            feedViewHolder.fireimage.setImageDrawable(getResources().getDrawable(R.drawable.fire));
        }

        if(modelFeed.plays.containsKey(mAuth.getUid())){
            feedViewHolder.playimage.setImageDrawable(getResources().getDrawable(R.drawable.play_button));
        }

        feedViewHolder.fireLinear.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                feedViewHolder.fireimage.setImageDrawable(getResources().getDrawable(R.drawable.fire));
                onFireClicked(mUSerCmt.child(modelFeed.getKey()),modelFeed.getUid());


            }
        });

        feedViewHolder.playLinear.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                feedViewHolder.playimage.setImageDrawable(getResources().getDrawable(R.drawable.play_button));
                sen_sound = modelFeed.getSen();

                mScoreRef.child(mAuth.getUid()).addListenerForSingleValueEvent(new ValueEventListener() {
                    @Override
                    public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                        final Model_Score modelScore = dataSnapshot.getValue(Model_Score.class);
                        long scoreCheck = modelScore.getScore();
                        if (scoreCheck < 1 ){
                            AlertDialog.Builder builder;
                            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
                                builder = new AlertDialog.Builder(context, android.R.style.Theme_Material_Dialog_Alert);
                            } else {
                                builder = new AlertDialog.Builder(context);
                            }
                            builder.setTitle("Insufficient Coins")
                                    .setMessage("You've insufficient coins in your wallet to listen this audio, Watch a reward video complete and get 50 coins.")
                                    .setPositiveButton(android.R.string.yes, new DialogInterface.OnClickListener() {
                                        public void onClick(DialogInterface dialog, int which) {

                                                long score = modelScore.getScore() + 5;
                                                Model_Score modelScore1 = new Model_Score(score, modelScore.getReput(), mAuth.getUid());
                                                mScoreRef.child(mAuth.getUid()).setValue(modelScore1);
                                            }
                                            scorez = modelScore.getScore();
                                            reputz = modelScore.getReput();

                                    })
                                    .setNegativeButton(android.R.string.no, new DialogInterface.OnClickListener() {
                                        public void onClick(DialogInterface dialog, int which) {
                                            Toast.makeText(mView.getContext(),"Our Apologies for inconvenience",Toast.LENGTH_SHORT).show();
                                        }
                                    })
                                    .setIcon(android.R.drawable.ic_dialog_alert)
                                    .show();
                        }else {

                            long score = modelScore.getScore() - 10;
                            Model_Score modelScore1 = new Model_Score(score, modelScore.getReput(), mAuth.getUid());
                            mScoreRef.child(mAuth.getUid()).setValue(modelScore1);

                        }
                    }

                    @Override
                    public void onCancelled(@NonNull DatabaseError databaseError) {

                    }
                });

            }
        });


    }

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

    public class FeedViewHolder extends RecyclerView.ViewHolder{

        CircleImageView circleImageView;
        TextView nameWord, statusword,fireword,playword;
        LinearLayout fireLinear, playLinear;
        ImageView fireimage, playimage;

        public FeedViewHolder(@NonNull View itemView) {
            super(itemView);

            circleImageView = itemView.findViewById(R.id.word_image);
            nameWord = itemView.findViewById(R.id.word_name);
            statusword = itemView.findViewById(R.id.word_status);
            fireword = itemView.findViewById(R.id.word_text_fire);
            playword = itemView.findViewById(R.id.word_text_play);
            fireLinear = itemView.findViewById(R.id.word_fire_linear);
            playLinear = itemView.findViewById(R.id.word_play_linear);
            fireimage = itemView.findViewById(R.id.word_img_fire);
            playimage = itemView.findViewById(R.id.word_img_play);



        }



    }
}

void sendReward(long scores, long reputs){
    long score = scores + 50;
    Model_Score modelScore1 = new Model_Score(score, reputs, mAuth.getUid());
    mScoreRef.child(mAuth.getUid()).setValue(modelScore1);
}

void showToast(String msg){
    Toast.makeText(mView.getContext(),msg,Toast.LENGTH_SHORT).show();
}


private void onFireClicked(DatabaseReference postRef, final String cr_uid) {
    postRef.runTransaction(new Transaction.Handler() {
        @Override
        public Transaction.Result doTransaction(MutableData mutableData) {
            Model_Feed p = mutableData.getValue(Model_Feed.class);
            if (p == null) {
                return Transaction.success(mutableData);
            }

            if (p.fires.containsKey(mAuth.getUid())) {
                // Unstar the post and remove self from stars
                p.firecount = p.firecount - 1;
                p.fires.remove(mAuth.getUid());
            } else {
                // Star the post and add self to stars
                p.firecount = p.firecount + 1;
                p.fires.put(mAuth.getUid(), true);
                mScoreRef.child(cr_uid).addListenerForSingleValueEvent(new ValueEventListener() {
                    @Override
                    public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                        Model_Score modelScore = dataSnapshot.getValue(Model_Score.class);

                        long reput = modelScore.getReput();
                        Model_Score modelScore1 = new Model_Score(modelScore.getScore(), reput + 10, cr_uid);
                        mScoreRef.child(cr_uid).setValue(modelScore1);

                    }

                    @Override
                    public void onCancelled(@NonNull DatabaseError databaseError) {

                    }
                });
            }

            // Set value and report transaction success
            mutableData.setValue(p);
            return Transaction.success(mutableData);
        }

        @Override
        public void onComplete(DatabaseError databaseError, boolean b,
                               DataSnapshot dataSnapshot) {
            // Transaction completed
            //Log.d(TAG, "postTransaction:onComplete:" + databaseError);
        }
    });
}


private void onPlayClicked(DatabaseReference postRef) {
    postRef.runTransaction(new Transaction.Handler() {
        @Override
        public Transaction.Result doTransaction(MutableData mutableData) {
            Model_Feed p = mutableData.getValue(Model_Feed.class);
            if (p == null) {
                return Transaction.success(mutableData);
            }

            if (p.plays.containsKey(mAuth.getUid())) {
                // Unstar the post and remove self from stars
                p.playcount = p.playcount + 1;
                p.plays.put(mAuth.getUid() + p.playcount,true);
                new readSen().execute();
            } else {
                // Star the post and add self to stars
                p.playcount = p.playcount + 1;
                p.plays.put(mAuth.getUid(), true);
            }

            // Set value and report transaction success
            mutableData.setValue(p);
            return Transaction.success(mutableData);
        }

        @Override
        public void onComplete(DatabaseError databaseError, boolean b,
                               DataSnapshot dataSnapshot) {
            // Transaction completed
            //Log.d(TAG, "postTransaction:onComplete:" + databaseError);
        }
    });
}

Answer 1

每当您设置新适配器时，recyclerview就会删除和分离旧适配器。相反，您可以尝试只更新当前适配器上的数据，其中一个简单的方法是在适配器上创建一个公共方法来重新分配数据：

public class FeedAdapter extends RecyclerView.Adapter<FeedAdapter.FeedViewHolder> {
    // ...
    public void setItems(List<Object> items) {
        mRecyclerViewItems = items;
    }
    // ...
}

然后在OnDataChange回调中更新适配器：

@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
    mRecyclerViewItems.clear();
    for (DataSnapshot dataSnapshot1 : dataSnapshot.getChildren()) {
        Model_Feed epiModel = dataSnapshot1.getValue(Model_Feed.class);
        mRecyclerViewItems.add(epiModel);
    }
    if (FeedAdapter != null) {
        FeedAdapter.setItems(mRecyclerViewItems);
        FeedAdapter. notifyDataSetChanged();
    } else {
        FeedAdapter = new FeedAdapter(mView.getContext(), mRecyclerViewItems);
        feedRecycler.setAdapter(FeedAdapter);
    }
}