java - 如何让我的回收器适配器检索发送到 firebase 数据库的消息？

Question

我无法在回收器适配器中显示聊天记录，我已经在 firebase 数据库中并且还附加了 firebase 回收器适配器

我已经尝试了一些让回收器适配器显示聊天但无法显示我的适配器的方法

private void DisplayReceiverInformation() {

    receiverName.setText(messageReceiverName);

    rootReference.child("Users").child(messageReceiverID).addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
            if (dataSnapshot.exists()) {

                //retrieve from db
                final String userName = dataSnapshot.child("fullName").getValue().toString();
                final String profileImage = dataSnapshot.child("profileImage").getValue().toString();

                //set values
                receiverName.setText(userName);
                Picasso.get().load(profileImage).placeholder(R.drawable.profile_image_placeholder).into(receiverProfileImage);
            }
        }

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

        }
    });
}

\\\

//initialize the above variables
private void InitializeFields() {

    Toolbar toolbar = findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    //connect chat custom bar to chat activity
    ActionBar actionBar = getSupportActionBar();
    Objects.requireNonNull(actionBar).setDisplayHomeAsUpEnabled(true);
    actionBar.setDisplayShowCustomEnabled(true);
    LayoutInflater layoutInflater = (LayoutInflater) this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    View action_bar_view = layoutInflater.inflate(R.layout.chat_custom_toolbar, null);
    actionBar.setCustomView(action_bar_view);

    receiverName = findViewById(R.id.custom_profile_name);
    receiverProfileImage = findViewById(R.id.custom_profile_image);

    sendMessageButton = findViewById(R.id.send_message_button);
    userMessageInput = findViewById(R.id.input_message);

   // messageAdapter = new MessagesAdapter(ChatActivity.this,)
    messageAdapter = new MessagesAdapter( messageList);
    userMessagesList = (RecyclerView) findViewById(R.id.messages_list_of_users);
    linearLayoutManager = new LinearLayoutManager(this);
    userMessagesList.setHasFixedSize(true);
    userMessagesList.setLayoutManager(linearLayoutManager);
    userMessagesList.setAdapter(messageAdapter);


}

\\\

@Override
protected void onStart() {

    super.onStart();

    rootReference.child("Messages").child(messageSenderID).child(messageReceiverID)
            .addChildEventListener(new ChildEventListener() {
                @Override
                public void onChildAdded(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {

                    Messages messages = dataSnapshot.getValue(Messages.class);

                    messageList.add(messages);


                    messageAdapter.notifyDataSetChanged();

                }

                @Override
                public void onChildChanged(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {

                }

                @Override
                public void onChildRemoved(@NonNull DataSnapshot dataSnapshot) {

                }

                @Override
                public void onChildMoved(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {

                }

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

                }
            });


}

\\\
MessagesAdapter.java

package com.MwandoJrTechnologies.the_smart_parent.Chats;



public class MessagesAdapter extends RecyclerView.Adapter<MessagesAdapter.MessageViewHolder> {

    private List<Messages> userMessagesList;
    private FirebaseAuth mAuth;
    private DatabaseReference usersDatabaseReference;

    public MessagesAdapter(List<Messages> userMessagesList) {
        this.userMessagesList = userMessagesList;
    }

    public class MessageViewHolder extends RecyclerView.ViewHolder {

        public TextView senderMessageText;
        public TextView receiverMessageText;
        public CircleImageView receiverProfileImage;

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

            senderMessageText = (TextView) itemView.findViewById(R.id.sender_message_text_view);
            receiverMessageText = (TextView) itemView.findViewById(R.id.receiver_message_text_view);
            receiverProfileImage = (CircleImageView) itemView.findViewById(R.id.receiver_message_profile_image);
        }
    }

    @NonNull
    @Override
    public MessageViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext())
                 .inflate(R.layout.message_layout_of_users, parent, false);

        mAuth = FirebaseAuth.getInstance();

        return new MessageViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull MessageViewHolder holder, int position) {

        //get senders ID
        String messageSenderID = mAuth.getCurrentUser().getUid();
        Messages messages = userMessagesList.get(position);

        //get ID of the receiver
        String fromUserID = messages.getFrom();
        //now get type of message whether text or image
        String fromMessageType = messages.getType();


        //retrieve receivers profile image
        usersDatabaseReference = FirebaseDatabase.getInstance().getReference().child("Users").child(fromUserID);
        usersDatabaseReference.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {

                if (dataSnapshot.hasChild("profileImage")){

                    String receiverImage = dataSnapshot.child("profileImage").getValue().toString();
                    Picasso.get().load(receiverImage).placeholder(R.drawable.profile_image_placeholder)
                            .into(holder.receiverProfileImage);
                }
            }

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

            }
        });

        if (fromMessageType.equals("text")){
            holder.receiverMessageText.setVisibility(View.INVISIBLE);
            holder.receiverProfileImage.setVisibility(View.INVISIBLE);

                    //display the message to the sender and to the receiver
            //for the receiver
            if (fromUserID.equals(messageSenderID)) {
                holder.senderMessageText.setBackgroundResource(R.drawable.sender_text_message_background);
                holder.senderMessageText.setTextColor(Color.WHITE);
                holder.senderMessageText.setGravity(Gravity.LEFT);
                holder.senderMessageText.setText(messages.getMessage());

                //for receiver
            } else {
                holder.senderMessageText.setVisibility(View.INVISIBLE);

                holder.receiverMessageText.setVisibility(View.VISIBLE);
                holder.receiverProfileImage.setVisibility(View.VISIBLE);

                holder.receiverMessageText.setBackgroundResource(R.drawable.receiver_text_message_background);
                holder.receiverMessageText.setTextColor(Color.WHITE);
                holder.receiverMessageText.setGravity(Gravity.LEFT);
                holder.receiverMessageText.setText(messages.getMessage());
            }
        }

    }

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

/// my modal class

Messages.java

package com.MwandoJrTechnologies.the_smart_parent.Chats;


//modal class to retrieve messages
public class Messages {

    public String date, time, type, message, from;

    public Messages(){
        //empty default constructor
    }

    //generate constructor with parameters

    public Messages(String date, String time, String type, String message, String from) {
        this.date = date;
        this.time = time;
        this.type = type;
        this.message = message;
        this.from = from;
    }

    //generate getter and setter


    public String getDate() {
        return date;
    }

    public void setDate(String date) {
        this.date = date;
    }

    public String getTime() {
        return time;
    }

    public void setTime(String time) {
        this.time = time;
    }

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    public String getFrom() {
        return from;
    }

    public void setFrom(String from) {
        this.from = from;
    }
}

上面的代码在 FirebaseRecycler 适配器中没有给我任何结果，但我希望它显示在 FirebaseRecycler 适配器中

Answer 1

我想答案在下面。

private void DisplayReceiverInformation() {
    receiverName.setText(messageReceiverName);
    rootReference.child("Users").child(messageReceiverID).addValueEventListener(new ValueEventListener() {
                @Override
                public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
        if (dataSnapshot.exists()) {

                            //retrieve from db
                            final String userName = dataSnapshot.child("fullName").getValue().toString();
                            final String profileImage = dataSnapshot.child("profileImage").getValue().toString();

                            //set values
                            receiverName.setText(userName);
                            Picasso.get().load(profileImage).placeholder(R.drawable.profile_image_placeholder).into(receiverProfileImage);

            messageAdapter = new MessagesAdapter( messageList);
            userMessagesList = (RecyclerView) findViewById(R.id.messages_list_of_users);
            linearLayoutManager = new LinearLayoutManager(this);
            userMessagesList.setHasFixedSize(true);
            userMessagesList.setLayoutManager(linearLayoutManager);
            userMessagesList.setAdapter(messageAdapter);
                     }
                }

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

                }
            });
        //here the data will be null so you must display data inside onDataChange() method.
}