单击recyclerview上的项目时的多个数据

Question

我尝试显示聊天列表，但是当我单击项目时，recyclerview 中的列表将重复，如图 1 所示，但是当我更改片段（底部导航）时，列表是正常的（不重复）。我的代码有什么问题，请帮忙

after item clicked before item clicked

这里是代码 AdapterChatlist

public class AdapterChatlist extends RecyclerView.Adapter<AdapterChatlist.Holder>{
Context context;
List<User> userList;//get user info
private HashMap<String, String> lastMsgMap;
public AdapterChatlist(Context context, List<User> userList) {
    this.context = context;
    this.userList = userList;
    lastMsgMap = new HashMap<>();
}
@NonNull
@Override
public Holder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
    //inflate layout row_chatlist
    View view = LayoutInflater.from(context).inflate(R.layout.row_chatlist, parent, false);
    return new Holder(view);
}
@Override
public void onBindViewHolder(@NonNull Holder holder, int position) {
    String hisUid = userList.get(position).getId();
    String userImg = userList.get(position).getImageUrl();
    String userName = userList.get(position).getFullname();
    String lastMsg = lastMsgMap.get(hisUid);

    holder.nameTv.setText(userName);
    if (lastMsg==null || lastMsg.equals("default")){
        holder.lastMsgTv.setVisibility(View.GONE);
    }else {
        holder.lastMsgTv.setVisibility(View.VISIBLE);
        holder.lastMsgTv.setText(lastMsg);
    }
    try {
        Glide.with(context).load(userImg)
                .placeholder(R.drawable.ic_pic)
                .into(holder.profileIv);
    }catch (Exception e){
        Glide.with(context).load(R.drawable.ic_pic)
                .into(holder.profileIv);
    }
    if (userList.get(position).getOnlineStat().equals("online")){
        holder.onlineStatIv.setImageResource(R.drawable.ic_online);
    }else {
        holder.onlineStatIv.setImageResource(R.drawable.ic_offline);
    }
    holder.itemView.setOnClickListener(view -> {
        Intent intent = new Intent(context, MessageActivity.class);
        intent.putExtra("userid", hisUid);
        context.startActivity(intent);
    });
}
public void setLastMsgMap(String userId, String lastMsg){
    lastMsgMap.put(userId, lastMsg);
}

@Override
public int getItemCount() {
    return userList.size();
}
class Holder extends RecyclerView.ViewHolder{
    ImageView profileIv, onlineStatIv;
    TextView nameTv, lastMsgTv;

    public Holder(@NonNull View itemView) {
        super(itemView);
        profileIv = itemView.findViewById(R.id.profileIv);
        onlineStatIv = itemView.findViewById(R.id.onlineStatIv);
        nameTv = itemView.findViewById(R.id.nameTv);
        lastMsgTv = itemView.findViewById(R.id.lastMsgTv);
    }
}}

这里是 ChatlistFragement

的代码

private void loadChats() {
    usersList = new ArrayList<>();
    ref = FirebaseDatabase.getInstance().getReference("Users");
    ref.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot snapshot) {
            for (DataSnapshot ds : snapshot.getChildren()) {
                User users = ds.getValue(User.class);
                for (Chatlist chatlist : chatlistList) {
                    if (users.getId() != null && users.getId().equals(chatlist.getId())) {
                        usersList.add(users);
                        break;
                    }
                }
                adapterChatlist = new AdapterChatlist(getContext(), usersList);
                //setAdapter
                rv_chatsList.setAdapter(adapterChatlist);
                //set last msg
                for (int i = 0; i < usersList.size(); i++) {
                    lastMsg(usersList.get(i).getId());
                }
            }
        }

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

        }
    });
}

private void lastMsg(final String userId) {
    DatabaseReference reference = FirebaseDatabase.getInstance().getReference("Chats");
    reference.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot snapshot) {
            String theLastMsg = "default";
            for (DataSnapshot ds : snapshot.getChildren()) {
                Chat chat = ds.getValue(Chat.class);
                if (chat == null) {
                    continue;
                }
                String sender = chat.getSender();
                String receiver = chat.getReceiver();
                if (sender == null || receiver == null) {
                    continue;
                }
                if (chat.getReceiver().equals(currentUser.getUid()) && chat.getSender().equals(userId) ||
                        chat.getReceiver().equals(userId) && chat.getSender().equals(currentUser.getUid())) {
                    theLastMsg = chat.getMessage();
                }
            }
            adapterChatlist.setLastMsgMap(userId, theLastMsg);
            adapterChatlist.notifyDataSetChanged();
        }

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

        }
    });
}

Answer 1

使用“adapterChatlist.setLastMsgMap(userId, theLastMsg);”您正在将一些新用户添加到现有列表中。我的猜测是，您应该拥有一个包含所有要显示的项目的列表，并始终清除适配器拥有的旧列表。因为这个 onDataChange() 可能会被多次调用，而不仅仅是一次，这就是你获得更多项目的原因。