错误：预计'）'

Question

我收到')'预计错误。我很确定这是因为它期待'})';'因为我在这一行上打开了一个括号“databaseClients.addValueEventListener (new ValueEventListener() {”。但是，当我添加/修改它时，程序仍然抱怨。不知道为什么。

这很可能是一个非常愚蠢的错误！ 任何帮助表示赞赏。干杯！

public class ViewProfile extends AppCompatActivity{ 

    ListView listviewClients; 
    List<Clients> clientsList; 

    DatabaseReference databaseClients; 

    protected void onCreate(Bundle savedInstanceState){ 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_view_profile); 

     listviewClients = (ListView) findViewById(R.id.listviewClients); 
     databaseClients = FirebaseDatabase.getInstance().getReference("clients"); 

     clientsList = new ArrayList<>(); 
    } 

    @Override 
    protected void onStart() { 
     super.onStart(); 

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

       clientsList.clear(); 

       for (DataSnapshot clientsSnapshot : dataSnapshot.getChildren()) { 
        Clients clients = clientsSnapshot.getValue(Clients.class); 

        clientsList.add(clients); 
       } 
       ClientsList adapter = new ClientsList(ViewProfile.this, clientsList); 
       listviewClients.setAdapter(adapter); 
      } 

      @Override 
      public void onCancelled(FirebaseError firebaseError) { 

      } 

     } 
    } 
} 

EDIT 当我添加}）;发生这种情况：

现在我得到的错误是：错误：（42，48）错误：不兼容的类型：不能转换到com.google.firebase.database.ValueEventListener。

Answer 1

这可能是与你的进口问题。您需要使用com.google.firebase.database.ValueEventListener。但我认为您在文件顶部的导入中会导入com.firebase.client.ValueEventListener。

Android Firebase: Can´t add ValueEventListener

Answer 2

public class ViewProfile extends AppCompatActivity{ 

ListView listviewClients; 
List<Clients> clientsList; 

DatabaseReference databaseClients; 

protected void onCreate(Bundle savedInstanceState){ 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_view_profile); 

    listviewClients = (ListView) findViewById(R.id.listviewClients); 
    databaseClients = FirebaseDatabase.getInstance().getReference("clients"); 

    clientsList = new ArrayList<>(); 
} 

@Override 
protected void onStart() { 
    super.onStart(); 

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

      clientsList.clear(); 

      for (DataSnapshot clientsSnapshot : dataSnapshot.getChildren()) { 
       Clients clients = clientsSnapshot.getValue(Clients.class); 

       clientsList.add(clients); 
      } 
      ClientsList adapter = new ClientsList(ViewProfile.this, clientsList); 
      listviewClients.setAdapter(adapter); 
     } 

     @Override 
     public void onCancelled(FirebaseError firebaseError) { 

     } 

    }); //here is your problem 
} 

}