java - 如何迭代 Firebase 数据库中的节点？

Question

我在 Firebase 中有一个简单的数据库，如下所示:

以下代码当前读取资源填充并将读取的每个项目渲染到 RecyclerView。

public class kos_putra extends Fragment {

    ArrayList<Kost> mList = new ArrayList<>();
    KostAdapter mAdapter;
    DatabaseReference mFirebaseDatabase;
    FirebaseDatabase mFirebaseInstance;

    public kos_putra() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View view = inflater.inflate(R.layout.kos_putra, container, false);

        RecyclerView recyclerView = (RecyclerView) view.findViewById(R.id.recyclerView);
        LinearLayoutManager layoutManager = new LinearLayoutManager(getActivity());
        recyclerView.setLayoutManager(layoutManager);
        mAdapter = new KostAdapter(mList);
        recyclerView.setAdapter(mAdapter);

        fillData();
        return view;
    }


    private void fillData() {
        Resources resources = getResources();
        String[] arJudul = resources.getStringArray(R.array.places);
        String[] arDeskripsi = resources.getStringArray(R.array.place_desc);
        String[] arLokasi = resources.getStringArray(R.array.place_locations);
        TypedArray a = resources.obtainTypedArray(R.array.places_picture);
        Drawable[] arFoto = new Drawable[a.length()];
        for (int i = 0; i < arFoto.length; i++) {
            BitmapDrawable bd = (BitmapDrawable) a.getDrawable(i);
            RoundedBitmapDrawable rbd =
                    RoundedBitmapDrawableFactory.create(getResources(), bd.getBitmap());
            rbd.setCircular(true);
            arFoto[i] = rbd;
        }
        a.recycle();

        for (int i = 0; i < arJudul.length; i++) {
            mList.add(new Kost(arJudul[i], arDeskripsi[i], arLokasi[i], arFoto[i]));
        }
        mAdapter.notifyDataSetChanged();
    }

    private void fetchDataFromFirebase(){
        mFirebaseInstance = FirebaseDatabase.getInstance();
        mFirebaseDatabase = mFirebaseInstance.getReference("kos_putra");
    }
}

现在我不想从文件中读取，而是想从 F​​irebase 中读取。如何迭代 kos_putra 下的每个节点？下图中，有4个物体。从逻辑上讲，我正在考虑先获取数据计数，然后执行 for 循环。但仍然不清楚如何做到这一点。

Answer 1

要在每个节点中进行迭代，请执行以下操作:

DatabaseReference ref=FirebaseDatabase.getInstance().getReference().child("kos_putra");
ref.addValueEventListener(new ValueEventListener(){
  @Override
public void onDataChange(DataSnapshot dataSnapshot){
  for(DataSnapshot data: dataSnapshot.getChildren()){
       String deskripsi=data.child("deskripsi").getValue().toString();
       String nama=data.child("nama").getValue().toString();
    }
  }
      @Override
   public void onCancelled(FirebaseError firebaseError) {

        }
   });

您的数据快照位于 kos_putra ，在该位置添加一个监听器将在所有节点(1,2,3,4)上进行迭代，并且使用 for 循环它将获取所有节点内的值。