如何修复空的recyclerview

Question

This is mydatabase on firebase

我正在从Firebase添加数据，但是在手机中运行该应用程序时，RecyclerView为空白，并且从Oncancelled方法中收到错误消息。 我的数据库包含四个字段，名称，电子邮件，权限和链接（字符串）。

public class MainActivity extends AppCompatActivity {

    DatabaseReference reference;
    RecyclerView recyclerView;
    ArrayList<Profile> list;
    MyAdapter adapter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        recyclerView = (RecyclerView) findViewById(R.id.myRecycler);
        recyclerView.setLayoutManager( new LinearLayoutManager(this));


        reference = FirebaseDatabase.getInstance().getReference().child("Profile");
        list = new ArrayList<Profile>();
        reference.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                Toast.makeText(MainActivity.this, "Inside the data change", Toast.LENGTH_SHORT).show();
                for(DataSnapshot dataSnapshot1: dataSnapshot.getChildren())
                {
                    Toast.makeText(MainActivity.this, "Inside the for loop", Toast.LENGTH_SHORT).show();
                    Profile p = dataSnapshot1.getValue(Profile.class);
                    list.add(p);

                }
                adapter = new MyAdapter(MainActivity.this,list);
                recyclerView.setAdapter(adapter);
            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {
                Toast.makeText(MainActivity.this, "Opsss.... Something is wrong", Toast.LENGTH_SHORT).show();
            }

        });
    }
}