java - 从 firebase 数据库中成功获取数据但无法在 Recyclerview 中显示

Question

消息适配器类

public class MessageAdapter extends RecyclerView.Adapter<MessageAdapter.MessageViewHolder>{
private List<Messages> mMessagesList;
private FirebaseAuth mAuth;

public MessageAdapter (List<Messages>mMessagesList)

{
    this.mMessagesList = mMessagesList;
}

@Override
public MessageViewHolder onCreateViewHolder(ViewGroup parent, int viewType)
{
    View V = LayoutInflater.from(parent.getContext()).inflate(R.layout.activity_chat_custom,parent,false);
    mAuth = FirebaseAuth.getInstance();
    return new MessageViewHolder(V);
}



public class MessageViewHolder extends RecyclerView.ViewHolder{
    public TextView messageText;
    public MessageViewHolder(View view)
    {
        super(view);
        messageText = (TextView)view.findViewById(R.id.message_text_layout);
    }
}




@SuppressLint("ResourceType")
@Override
public void onBindViewHolder(MessageViewHolder holder, int position) {

        String current_user_id = mAuth.getInstance().getCurrentUser().getUid();
        Messages messages = mMessagesList.get(position);
        String from_user = messages.getFrom();

//        if (from_user!=null && from_user.equals(current_user_id)){
//                holder.messageText.setBackgroundResource(R.drawable.text_background1);
//                holder.messageText.setTextColor(Color.red(R.color.red));
//            }else {
//                holder.messageText.setBackgroundResource(R.drawable.text_background2);
//                holder.messageText.setTextColor(Color.red(R.color.black));
//            }

        holder.messageText.setText(messages.getMessage());
    }

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

聊天.java

    private RecyclerView messageList;
private List<Messages> messagesList = new ArrayList<>();
private LinearLayoutManager linearLayoutManager;
private MessageAdapter mAdapter;

String MessageSenderId;
String MessageRecieverId;

final DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
    MessageSenderId = mAuth.getCurrentUser().getUid();
    MessageRecieverId = getIntent().getStringExtra("Recievers_Id");

    messageList = (RecyclerView) findViewById(R.id.message_list);
    linearLayoutManager = new LinearLayoutManager(this);
    mAdapter = new MessageAdapter(messagesList);
//        messageList.setHasFixedSize(true);
    messageList.setLayoutManager(linearLayoutManager);
    messageList.setAdapter(mAdapter);

 private void fetchMessages() {

   rootRef.child("Messages").child(MessageSenderId).child(MessageRecieverId).addChildEventListener(new ChildEventListener() {
        @Override
        public void onChildAdded(DataSnapshot dataSnapshot, String s) {
            Messages message = dataSnapshot.getValue(Messages.class);
            messagesList.add(message);
            mAdapter.notifyDataSetChanged();


            Log.d("Tag", dataSnapshot.child("Message").getValue().toString());
        }

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

        }

        @Override
        public void onChildRemoved(DataSnapshot dataSnapshot) {

        }

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

        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });
}

XML 布局

活动聊天

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto">

<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:minHeight="?attr/actionBarSize"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#000000"
app:titleTextColor="#ffffff"
>
<TextView
 android:textColor="@color/white"
 android:id="@+id/name"
 android:layout_width="275dp"
 android:layout_height="match_parent" />
</android.support.v7.widget.Toolbar>

<android.support.v7.widget.RecyclerView
 android:id="@+id/message_list"
 android:layout_above="@+id/send_message"
 android:layout_below="@+id/toolbar"
 android:layout_width="match_parent"
 android:layout_height="match_parent"> 
</android.support.v7.widget.RecyclerView>

<Button
 android:id="@+id/add_image"
 android:layout_width="50dp"
 android:layout_height="wrap_content"
 android:layout_alignParentBottom="true"
 android:layout_alignParentStart="true" />

<EditText
 android:layout_marginLeft="5dp"
 android:id="@+id/input_message"
 android:layout_width="240dp"
 android:layout_height="wrap_content"
 android:layout_alignParentBottom="true"
 android:layout_toStartOf="@+id/send_message" />

<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Send"
android:id="@+id/send_message"
android:layout_alignParentBottom="true"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true" />
</RelativeLayout>

自定义布局

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/message_single_layout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="12dp">

<TextView
    android:id="@+id/message_text_layout"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentStart="true"
    android:layout_alignParentTop="true"
    android:background="@drawable/messages_text_background"
    android:padding="10dp"
    android:text="Textview"
    android:textSize="20dp" />

</RelativeLayout>

之前recyclerview我使用了一个列表视图，它工作得很好，就像预期的那样......然后由于显而易见的原因，我切换到回收视图，我遇到了这个问题

截图 = https://ibb.co/gcve67

在 logcat 中，我尝试使用 Log.d 获取数据并且它有效......所以我知道数据正在被获取但无法在其中显示它recyclerview...... Recyclerview 规则也有轻微变化，因为我上次以前我不确定我使用的方式是否正确……如果正确的话，我坚信布局有问题，但就是想不通……请帮忙……卡在这里好几个星期

标签： javaandroiddatabasefirebasefirebase-realtime-database