java Recyclerview和适配器未显示

Question

https://www.youtube.com/watch?v=M8sKwoVjqU0 我看了这段视频，我也做了同样的事情。但有一个问题，我猜myadapter类不起作用，因为当我单击按钮时，它会出现如图所示的白色屏幕。当我检查日志时，我无法找出故障在哪里没有问题。但我只想把数据从firebase传输到textview。但我不能得到任何结果，至少它必须看到有文本视图，它有文本名，但我不能看到我的活动。我可能不知道将要显示的真实页面

---这是我的适配器。阶级----

public class Myadapter extends RecyclerView.Adapter<Myadapter.MyViewHolder> {
Context context;
ArrayList<User> list ;
public Myadapter(Context context, ArrayList<User> list) {
    this.context = context;
    this.list = list;
}
@NonNull
@Override
public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
    View v = LayoutInflater.from(context).inflate(R.layout.item,parent,false);

    return new MyViewHolder(v) ;
}
@Override
public void onBindViewHolder(@NonNull MyViewHolder holder, int position) {


 User user =list.get(position);
   holder.textView.setText(user.getTitle());
    }
    @Override
    public int getItemCount() {
  return  list.size();
    }
    public static class MyViewHolder extends RecyclerView.ViewHolder{
TextView textView, TextView;
    public MyViewHolder(@NonNull View itemView) {
        super(itemView);
        TextView = itemView.findViewById(R.id.txtview);
        textView=itemView.findViewById(R.id.title);
    }
}

---这是我的用户列表。阶级---

public class userlist extends AppCompatActivity {
RecyclerView recyclerView;
        DatabaseReference database;
        Myadapter myadapter;
        ArrayList<User>list;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_userlist);
    recyclerView=findViewById(R.id.userlist);
    database = FirebaseDatabase.getInstance().getReference("users");
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
list = new ArrayList<>();
myadapter = new Myadapter(this,list);
recyclerView.setAdapter(myadapter);
database.addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(@NonNull DataSnapshot snapshot) {
        for ( DataSnapshot dataSnapshot: snapshot.getChildren()){
            User user=dataSnapshot.getValue(User.class);
list.add(user);
        }
        myadapter.notifyDataSetChanged();
    }

---这是我的主要活动。阶级---

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Button button1 = (Button) findViewById(R.id.button);
button1.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
        Intent i = new Intent(MainActivity.this,userlist.class);
        startActivity(i);
        finish();}
});
    }
}

{ "users" : { "value1" : { "title" : "reachthis" } } }