Android無法使用Firebase中保存的數據填充TextView

我遇到了一個問題，我嘗試使用先前創建的數據創建一個使用來自Firebase數據庫的數據填充的着陸頁。我使用這裏在MainActivityAndroid無法使用Firebase中保存的數據填充TextView

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) { 

     } 
    });

我使用DatabaseReference獲取的ID碼，這似乎通過，該方案沒有按它轉換成一個TextView，當我嘗試將該信息輸出到然而工作似乎沒有用我的數據庫中的'名稱'字段替換文本視圖文本

來源

2017-03-16 Mark Barton

在發佈後解決了我自己的問題！

簡單修復，放在我放的線上;

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

我以爲我引用了我的ID，但getRef（）是錯誤的使用。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");

來源

2017-03-16 23:24:25

Android無法使用Firebase中保存的數據填充TextView

回答

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