java - Firebase 的 ListView 聊天消息

Question

我创建了一个涉及与其他人聊天的应用程序，为了使聊天 Activity 更加赏心悦目，我创建了一个 ListView 来更改每条消息的 UI。当我发送消息时，第一条消息会出现并正确显示，但如果我发送另一条消息，它会覆盖 listView 中的前一条消息，而不是仅仅向 ListView 添加另一个值，这是我的代码:

聊天 Activity :

private void append_chat_conversation(DataSnapshot dataSnapshot) {
        for (DataSnapshot ds : dataSnapshot.getChildren()) {
            Log.e("Chat details: ", String.valueOf(ds));
            chat_username = dataSnapshot.child("username").getValue(String.class);
            chat_msg = dataSnapshot.child("message").getValue(String.class);

            Chat chat = new Chat(chat_username, chat_msg);
            ArrayList<Chat> chatList = new ArrayList<>();
            chatList.add(chat);

            chatListAdapter adapter = new chatListAdapter(this, R.layout.chat_message, chatList);
            mListView.setAdapter(adapter);
            Log.e("Chat username: ", "" + chat_username);
            Log.e("Chat message: ", "" + chat_msg);

        }
}

聊天列表适配器:

public class chatListAdapter extends ArrayAdapter<Chat> {

    private Context mContext;
    int mResource;
    TextView usernameTV, messageTV;

    public chatListAdapter(Context context, int resource, ArrayList<Chat> objects) {
        super(context, resource, objects);
        mContext = context;
        mResource = resource;

    }

    @NonNull
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        String username = getItem(position).getUsername();
        String message = getItem(position).getMessage();

        Chat chat = new Chat(username, message);

        LayoutInflater inflater = LayoutInflater.from(mContext);
        convertView = inflater.inflate(mResource, parent, false);

        usernameTV = convertView.findViewById(R.id.username_chat);
        messageTV = convertView.findViewById(R.id.message_chat);

        usernameTV.setText(username);
        messageTV.setText(message);

        return convertView;
    }
}

我不会添加其他代码(getter 和 setter 或各个消息的实际布局)，因为我认为这不是问题。如果您需要其他任何信息，请告诉我，我确信我在这里做了一些愚蠢的事情来实现这一点，

谢谢，内森

编辑:

我终于找到了如何添加到 ListView 而不用此代码覆盖它:

private void append_chat_conversation(DataSnapshot dataSnapshot) {
        for (DataSnapshot ds : dataSnapshot.getChildren()) {
            Log.e("Chat details: ", String.valueOf(ds));
            chat_username = dataSnapshot.child("username").getValue(String.class);
            chat_msg = dataSnapshot.child("message").getValue(String.class);

            Chat chat = new Chat(chat_username, chat_msg);
            chatList.add(chat);
            Log.e("Chat username: ", "" + chat_username);
            Log.e("Chat message: ", "" + chat_msg);
        }
        adapter.notifyDataSetChanged();
    }

数组列表和 adpater 是顶部的公共(public)变量，但它仍然显示该消息两次。我仍然需要找到解决办法。感谢您的帮助

Answer 1

您可以使用 FirebaseListAdapter 显示来自 Firebase 的消息，并对列表中的消息应用自定义布局。

    FirebaseDatabase database = FirebaseDatabase.getInstance();
    Query messages = database.getReference("chatrooms").child(sessionId).child("messages");

    FirebaseListOptions<Message> options = new FirebaseListOptions.Builder<Message>().setQuery(messages, Message.class).setLayout(R.layout.message).build();

    ListView messageList = chatActivity.findViewById(R.id.message_list);
    adapter = new FirebaseListAdapter<Message>(options){
        @Override
        protected void populateView(View v, Message model, int position) {
            // Get references to the views of message.xml
            TextView messageText = v.findViewById(R.id.message_text);
            TextView messageUser = v.findViewById(R.id.message_user);
            TextView messageTime = v.findViewById(R.id.message_time);

            // Set their text
            messageText.setText(model.getMessageBody());
            messageUser.setText(model.getUser());

            // Format the date before showing it
            messageTime.setText(DateFormat.format("dd-MM-yyyy (HH:mm:ss)",
                    model.getTime()));
        }
    };

    messageList.setAdapter(adapter);
    adapter.startListening();

在此处查看更多信息:https://code.tutsplus.com/tutorials/how-to-create-an-android-chat-app-using-firebase--cms-27397