图像滑块不从firebase实时数据库提取

Question

我正在使用viewpager使用滑块，此滑块显示一些图像。我将此图像存储在我的Firebase数据库中，但此应用程序被粉碎并在addValueEventListener方法中显示错误。

主要活动。Java语言

   sliderpager = findViewById(R.id.slider);
   lstSlides = new ArrayList<SliderModel>();

   SliderPageAdapter sliderPageAdapter = new SliderPageAdapter(MainActivity.this,lstSlides);
   sliderPageAdapter.notifyDataSetChanged();
   sliderpager.setAdapter(sliderPageAdapter);

   database = FirebaseDatabase.getInstance();
   reference = database.getReference("Image");

   reference.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
            for (DataSnapshot img : dataSnapshot.getChildren()){
                SliderModel sm = img.getValue(SliderModel.class);
                lstSlides.add(sm);
             }
         }

         @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {

            }
        });

SliderPageAdapter.java

    private Context ctx;
    List<SliderModel> SliderModels;

    public SliderPageAdapter(Context ctx, List<SliderModel> SliderModels) {
        this.ctx = ctx;
        this.SliderModels = SliderModels;
    }

    @Override
    public int getCount() {
        return SliderModels.size();
    }

    @NonNull
    @Override
    public Object instantiateItem(@NonNull ViewGroup container, int position) {
        LayoutInflater inflater = (LayoutInflater) ctx.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        View slideLayout = inflater.inflate(R.layout.slider_row,null);

        ImageView slideImg = slideLayout.findViewById(R.id.sliderimg);
        Picasso.get().load(SliderModels.get(position).getImage()).into(slideImg);
        container.addView(slideLayout);
        return slideLayout;
    }

    @Override
    public boolean isViewFromObject(@NonNull View view, @NonNull Object object) {
        return view == object;
    }

    @Override
    public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object object) {
        super.destroyItem(container, position, object);
        container.removeView((View)object);
    }

SliderModel.java

    private String image;

    public SliderModel() {

    }

    public SliderModel(String image) {
        this.image = image;
    }

    public String getImage() {
        return image;
    }

    public void setImage(String image) {
        this.image = image;
    }

如何解决此错误？

Answer 1

您需要删除for循环，因为当您进行迭代时，检索到的数据类型是String。因此，请执行以下操作：

    reference.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                SliderModel sm = dataSnapshot.getValue(SliderModel.class);
                lstSlides.add(sm);
            }

        }