Android不會使用保存在Firebase中的數據填充TextView

Question

我在嘗試創建登錄頁面時遇到問題，該登錄頁面使用以前創建的數據填充了Firebase數據庫中的數據。 我在MainActivity中使用代碼

public class MainActivity extends AppCompatActivity
    implements NavigationView.OnNavigationItemSelectedListener {


private FirebaseAuth firebaseAuth;
FirebaseDatabase firebaseDatabase;
DatabaseReference databaseReference;

private TextView userName;

NavigationView navigationView = null;
Toolbar toolbar = null;


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


    //FIREBASE LOGGED IN CHECK

    firebaseAuth = FirebaseAuth.getInstance();

    if(firebaseAuth.getCurrentUser() == null){
        finish();
        startActivity(new Intent(this, LoginActivity.class));
    }

    FirebaseUser user = firebaseAuth.getCurrentUser();


    //Set the fragment initially
    MainFragment fragment = new MainFragment();
    android.support.v4.app.FragmentTransaction fragmentTransaction =
            getSupportFragmentManager().beginTransaction();
    fragmentTransaction.replace(R.id.fragment_container, fragment);
    fragmentTransaction.commit();

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

    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Snackbar.make(view, "Nothing to see here, move along!", Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show();
        }
    });



    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);

    ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
            this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
    drawer.setDrawerListener(toggle);
    toggle.syncState();

    navigationView = (NavigationView) findViewById(R.id.nav_view);

    View headerView = navigationView.getHeaderView(0);

    userName = (TextView) headerView.findViewById(R.id.textViewUserName);


    //GET INSTANCE OF DATABASE FROM URL
    firebaseDatabase = FirebaseDatabase.getInstance();
    databaseReference = firebaseDatabase.getReferenceFromUrl("https://userdata-57a47.firebaseio.com/");

    DatabaseReference mChild = databaseReference.getRef().child("name");

    mChild.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {

            String name = dataSnapshot.getValue(String.class);

            userName.setText(name);

        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });

我正在使用DatabaseReference來獲取ID，但似乎可以正常工作，但是當我嘗試通過使用將其轉換為TextView來輸出此信息時，該程序似乎並沒有將Textview文本替換為“ name”字段。數據庫

Answer 1

發布后幾分鍾解決了我自己的問題！

簡單的修復，在我放置的位置；

DatabaseReference mChild = databaseReference.getRef().child("name");

我以為我引用了我的ID，但是getRef（）是錯誤的用法。 相反，我應該使用.getUid（）。 所以現在我的代碼看起來像這樣...

DatabaseReference mChild = databaseReference.child(user.getUid().child("name");