从firebase中的子节点的子节点检索数据

Question

我想检索Firebase DB中子节点的子节点的所有差事名称。

但是，我只能在第二个子节点（随机密钥）之前引用 这是我的代码;

  View view = inflater.inflate(R.layout.tab1,container,false);
    String r = "Errands";
    root = FirebaseDatabase.getInstance().getReference().child(r);
    list = (ListView) view.findViewById(R.id.mylistview);

    arrayAdapter = new ArrayAdapter<String>(getActivity(),android.R.layout.simple_list_item_1,list_of_errands);

    list.setAdapter(arrayAdapter);

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


            Set<String> set = new HashSet<String>();
            Iterator i = dataSnapshot.getChildren().iterator();

            while (i.hasNext()) {
                set.add(((DataSnapshot) i.next()).getKey());
            }

请帮助

Answer 1

请使用此代码：

DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference errandsRef = rootRef.child("Errands");
ValueEventListener eventListener = new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        for(DataSnapshot ds : dataSnapshot.getChildren()) {
            String key = ds.getKey();

            DatabaseReference keyRef = rootRef.child("Errands").child(key);
            ValueEventListener valueEventListener = new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {
                    String Errand = ds.child("Errand").getValue(String.class);
                    Log.d("TAG", Errand);
                }

                @Override
                public void onCancelled(DatabaseError databaseError) {}
            };
            keyRef.addListenerForSingleValueEvent(valueEventListener);
        }
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {}
};
errandsRef.addListenerForSingleValueEvent(eventListener);

您的输出将是：

Go to Strath
//and so on

希望它有所帮助。