java - 我想使用回收器 View 从 firebase 获取数据到内部 fragment

Question

我正在尝试为自己创建一个项目。我在某个时候陷入困境。

我想使用回收器 View 将数据从 firebase 获取到内部 fragment 。

我真的需要你的帮助。

我尝试了几种方法。但我做不到。我创建了 recyclerviewconfig 和 firebasehelper 类，但它不起作用。今天我尝试了 firebaseUI。但又没用。

public class Kumas extends Fragment {

    private View KumasFragmet;
    private RecyclerView KumasListesi;
    private DatabaseReference MaliyetKumasListesiReference;


    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        KumasFragmet= inflater.inflate(R.layout.fragment_kumas, container, false);

        MaliyetKumasListesiReference = FirebaseDatabase.getInstance().getReference().child("test carisi").child("modeller").child("1").child("maliyet").child("kumas");

        KumasListesi = (RecyclerView) KumasFragmet.findViewById(R.id.maliyet_kumaş_rw);
        KumasListesi.setLayoutManager(new LinearLayoutManager(getContext()));


        FloatingActionButton flt = (FloatingActionButton) KumasFragmet.findViewById(R.id.kumas_ekle_floating);
        flt.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent in = new Intent(getActivity(),KumasEkle.class);
                startActivity(in);
            }
        });

        return KumasFragmet;
    }

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

        FirebaseRecyclerOptions<KumasTanim> options = new FirebaseRecyclerOptions.Builder<KumasTanim>()
                .setQuery(MaliyetKumasListesiReference,KumasTanim.class)
                .build();

        FirebaseRecyclerAdapter<KumasTanim,MaliyetKumasListesiViewHolder> adapter =
                new FirebaseRecyclerAdapter<KumasTanim, MaliyetKumasListesiViewHolder>(options) {
                    @Override
                    protected void onBindViewHolder(@NonNull final MaliyetKumasListesiViewHolder maliyetKumasListesiViewHolder, int i, @NonNull KumasTanim kumasTanim) {

                                maliyetKumasListesiViewHolder.kumas_adi.setText(kumasTanim.getKumas_adi());
                                maliyetKumasListesiViewHolder.sarfiyat.setText(kumasTanim.getSarfiyat());
                                maliyetKumasListesiViewHolder.fiyat.setText(kumasTanim.getFiyat());



                    }

                    @NonNull
                    @Override
                    public MaliyetKumasListesiViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
                        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.maliyet_kumas_item,parent,false);
                        MaliyetKumasListesiViewHolder maliyetKumasListesiViewHolder = new MaliyetKumasListesiViewHolder(view);
                        return maliyetKumasListesiViewHolder;
                    }
                };
        KumasListesi.setAdapter(adapter);
        adapter.startListening();
    }

    public static class MaliyetKumasListesiViewHolder extends RecyclerView.ViewHolder {

        TextView kumas_adi,sarfiyat,fiyat;

        public MaliyetKumasListesiViewHolder(@NonNull View itemView) {
            super(itemView);

            kumas_adi = itemView.findViewById(R.id.item_kumas_adi_tw);
            sarfiyat = itemView.findViewById(R.id.item_sarfiyat_tw);
            fiyat = itemView.findViewById(R.id.item_fiyat_tw);
        }
    }
}

它没有给出任何错误。

Answer 1

请添加事件监听器，如果您没有获取数据，那么您可能会收到数据库错误。请先检查该错误。首先解决问题。

  MaliyetKumasListesiReference .addValueEventListener(new ValueEventListener() {
      @Override
          public void onDataChange(DataSnapshot dataSnapshot) {
          Post post = dataSnapshot.getValue(Post.class);
          System.out.println(post);
       }

      @Override
          public void onCancelled(DatabaseError databaseError) {
            System.out.println("The read failed: " + databaseError.getCode());
         }
       });