Question

这是我的数据库的屏幕截图，我已经尝试了很多来检索数据，但似乎总是返回null。我正在使用firebase数据库。我想知道如何将此数据检索到此布局中。顺便说一句，我是java和android的新手，所以在回答这个问题时请考虑一下。我遇到的另一个问题是如何在点击图像时传递图像的意图。我在家庭布局中使用多个图像视图，我不明白如何处理它。提前谢谢。

//从数据库中检索的产品图片 mDatabaseRef.child（＆＃34; Products＆＃34;）。addValueEventListener（new ValueEventListener（）{

        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            Product product = dataSnapshot.child("Product ID").getValue(Product.class);

            product_1_name = dataSnapshot.child("Product 1").child("Product Name").getValue().toString();
            product_1_price = dataSnapshot.child("Product 1").child("Product Price").getValue().toString();
            product_1_urlimage = dataSnapshot.child("Product 1").child("Product Image").getValue().toString();

            product_2_name = dataSnapshot.child("Product 2").child("Product Name").getValue().toString();
            product_2_price = dataSnapshot.child("Product 2").child("Product Price").getValue().toString();
            product_2_urlimage = dataSnapshot.child("Product 2").child("Product Image").getValue().toString();

            product_3_name = dataSnapshot.child("Product 3").child("Product Name").getValue().toString();
            product_3_price = dataSnapshot.child("Product 3").child("Product Price").getValue().toString();
            product_3_urlimage = dataSnapshot.child("Product 3").child("Product Image").getValue().toString();

            product_4_name = dataSnapshot.child("Product 4").child("Product Name").getValue().toString();
            product_4_price = dataSnapshot.child("Product 4").child("Product Price").getValue().toString();
            product_4_urlimage = dataSnapshot.child("Product 4").child("Product Image").getValue().toString();

            product_5_name = dataSnapshot.child("Product 5").child("Product Name").getValue().toString();
            product_5_price = dataSnapshot.child("Product 5").child("Product Price").getValue().toString();
            product_5_urlimage = dataSnapshot.child("Product 5").child("Product Image").getValue().toString();

            product_6_name = dataSnapshot.child("Product 6").child("Product Name").getValue().toString();
            product_6_price = dataSnapshot.child("Product 6").child("Product Price").getValue().toString();
            product_6_urlimage = dataSnapshot.child("Product 6").child("Product Image").getValue().toString();

            product_7_name = dataSnapshot.child("Product 7").child("Product Name").getValue().toString();
            product_7_price = dataSnapshot.child("Product 7").child("Product Price").getValue().toString();
            product_7_urlimage = dataSnapshot.child("Product 7").child("Product Image").getValue().toString();
        }


        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });

private View.OnClickListener HomeImageClickListener = new View.OnClickListener（）{ 意图;

    @Override
    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.iv_hotcakes_topleft:
                intent = new Intent(getContext(), ProductDetailActivity.class);
                intent.putExtra("title", product_1_name);
                intent.putExtra("url", product_1_urlimage);
                intent.putExtra("price", product_2_price);
                startActivity(intent);
                break;
            case R.id.iv_hotcakes_bottomleft:

                intent = new Intent(getContext(), ProductDetailActivity.class);
                intent.putExtra("title", product_2_name);

                intent.putExtra("url", product_2_urlimage);
                intent.putExtra("price", product_2_price);

                startActivity(intent);
                break;
            case R.id.iv_hotcakes_right:

                intent = new Intent(getContext(), ProductDetailActivity.class);
                intent.putExtra("title", product_3_name);

                intent.putExtra("url", product_3_urlimage);
                intent.putExtra("price", product_3_price);

                startActivity(intent);
                break;
            case R.id.iv_specials_left:

                intent = new Intent(getContext(), ProductDetailActivity.class);
                intent.putExtra("title", product_4_name);

                intent.putExtra("url", product_4_urlimage);
                intent.putExtra("price", product_4_price);

                startActivity(intent);
                break;
            case R.id.iv_specials_right:

                intent = new Intent(getContext(), ProductDetailActivity.class);
                intent.putExtra("title", product_5_name);
                intent.putExtra("url", product_5_urlimage);
                intent.putExtra("price", product_5_price);
                startActivity(intent);
                break;
            case R.id.iv_categories_top_left:

                intent = new Intent(getContext(), ProductDetailActivity.class);
                intent.putExtra("title", product_6_name);

                intent.putExtra("url", product_6_urlimage);
                intent.putExtra("price", product_6_price);
                startActivity(intent);
                break;
            case R.id.iv_categories_top_right:
                intent = new Intent(getContext(), ProductDetailActivity.class);
                intent.putExtra("title", product_7_name);

                intent.putExtra("url", product_7_urlimage);
                intent.putExtra("price", product_7_price);
                startActivity(intent);
                break;
            case R.id.iv_categories_center_left:

                intent = new Intent(getContext(), ProductDetailActivity.class);
                intent.putExtra("title", "Muffins");
                intent.putExtra("url", url);
                intent.putExtra("price", "280");
                startActivity(intent);
                break;
            case R.id.iv_categories_center_right:

                intent = new Intent(getContext(), ProductDetailActivity.class);
                intent.putExtra("title", "Muffins");
                intent.putExtra("url", url);
                intent.putExtra("price", "280");
                startActivity(intent);
                break;
            case R.id.iv_categories_bottom_left:

                intent = new Intent(getContext(), ProductDetailActivity.class);
                intent.putExtra("title", "Muffins");
                intent.putExtra("url", url);
                intent.putExtra("price", "280");
                startActivity(intent);
                break;
            case R.id.iv_categories_bottom_right:

                intent = new Intent(getContext(), ProductDetailActivity.class);
                intent.putExtra("title", "Muffins");
                intent.putExtra("url", url);
                intent.putExtra("price", "280");
                startActivity(intent);
                break;

        }


    }
};

https://ibb.co/hpviJk

https://ibb.co/et9wM5

Answer 1

使用orderByValue（）这将完成你的工作

    mReference.child("Products").orderByValue().addChildEventListener(new ChildEventListener() {
        @Override
        public void onChildAdded(DataSnapshot dataSnapshot, String s) {

            ProductsClass productsClass = dataSnapshot.getValue(ProductsClass.class);

            if(productsClass!=null)
            {
                // do what ever you want
            }else
                Log.d(TAG, "onChildAdded: NULL");

        }

        @Override
        public void onChildChanged(DataSnapshot dataSnapshot, String s) {

        }

        @Override
        public void onChildRemoved(DataSnapshot dataSnapshot) {

        }

        @Override
        public void onChildMoved(DataSnapshot dataSnapshot, String s) {

        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });

//这不是代码的一部分，而是如何使用hashmap

ArrayList<HashMap<String,String>> list = new ArrayList<>();
        //HashMap<KEY,VALUE>
        // just a example how to use hashmap in list
        for(int i = 0;i<3;i++)
        {           
            HashMap<String,String> map = new HashMap<>();
            map.put("product_key"+i,"product_name"+i);
            map.put("product_key_image"+i,"product_image_link"+i);
            list.add(map);
        }
        // to get values

        for(int i=0;i<list.size();i++)
        {
            HashMap<String,String> map = list.get(i);
            System.out.println("product name is "+map.get("product_key"+i));
            System.out.println("product name is "+map.get("product_key"+i));
        }

        //for single value

        HashMap<String,String> map = new HashMap<>();
        map.put("name", "salman");
        map.put("full_name", "123123123");


        System.out.println(map.get("name"));
        System.out.println(map.get("full_name"));

<强>输出：

product name is product_name0
product name is product_name0
product name is product_name1
product name is product_name1
product name is product_name2
product name is product_name2
salman
123123123

将Firebase中的数据检索到布局中

1 个答案: