How can I retrieve this element in firebase realtime?

Question

I am saving items to firebase and I get the following structure

I am using the following code to try to retrieve the descripcion and precio data that is inside the second child

 DatabaseReference itemFactura = FirebaseDatabase.getInstance().getReference().child("factura");
 itemFactura.addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {

        if(dataSnapshot.exists()){
            int cantidad = 0;

            for (DataSnapshot snapshot : dataSnapshot.getChildren()){
                if(Boolean.parseBoolean(snapshot.child("estado").getValue().toString())){
                            ArrayList<String> elementos = new ArrayList<String>();
                            elementos.add(snapshot.child("descripcion").getValue().toString());
                            elementos.add(snapshot.child("precio").getValue().toString());
                            tabla.agregarFilaTabla(elementos);
                            cantidad = Integer.parseInt(snapshot.child("precio").getValue().toString()) + cantidad;
                }
            }
            cantidadTotal.setText(String.valueOf(cantidad));
        }

    }

But it marks me a null because it can't find them

Answer 1

You have two nested levels with dynamic keys in your JSON, so you need two nested loops over getChildren() in your onDataChange :

DatabaseReference itemFactura = FirebaseDatabase.getInstance().getReference().child("factura");
 itemFactura.addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        if(dataSnapshot.exists()){
            int cantidad = 0;
            for (DataSnapshot level1snapshot : dataSnapshot.getChildren()){
                for (DataSnapshot level2snapshot : level1snapshot.getChildren()){
                    if(level2snapshot.child("estado").getValue(Boolean.class) != null){
                        ...