适配器不显示Firebase实时数据库的产品图片和价格。

问题描述 投票：0回答：1

我正试图从Firebase实时数据库中检索数据（产品图片和价格），并将其放入回收器View中，但我遇到了一些困难。在我的数据库中，我存储了一个产品的图片url，我想把这个图片显示在放在cardView中的ImageView组件中。我也设法正确地检索了url和价格，但我的recyclerView没有显示它们。这是我的产品类。

public class CustomizeProduct {
    private String productImage;
    private String productName;
    private String productPrice;

    public CustomizeProduct(String image, String name, String price){
        this.productImage = image;
        this.productName = name;
        this.productPrice = price;
    }

    public String getProductImage() {
        return productImage;
    }
    public void setProductImage(String productImage){
        this.productImage = productImage;
    }

    public String getProductName() {
        return productName;
    }
    public void setProductName(String productName){
        this.productName = productName;
    }

    public String getProductPrice() { return productPrice; }
    public void setProductPrice(String productPrice) {
        this.productPrice = productPrice;
    }
}

我的适配器如下

public class ProductAdapter extends RecyclerView.Adapter<ProductAdapter.ViewHolder> {
    private ArrayList<CustomizeProduct> customized;
    private Context myContext;

    public static class ViewHolder extends RecyclerView.ViewHolder {

        public ImageView thisProductImage;
        public TextView thisProductName;
        public TextView thisProductPrice;

        public ViewHolder(View itemView) {
            super(itemView);
            thisProductImage = itemView.findViewById(R.id.customProductImage);
            thisProductName = itemView.findViewById(R.id.customProductName);
            thisProductPrice = itemView.findViewById(R.id.customProductPrice);
        }
    }

    public ProductAdapter(Context context, ArrayList<CustomizeProduct> thisCustom) {
        myContext = context;
        customized = thisCustom;
    }

    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.ingredients, parent, false);
        ViewHolder mv = new ViewHolder(v);
        return mv;
    }

    public void onBindViewHolder(ViewHolder holder, int position) {
        CustomizeProduct currentCustom = customized.get(position);
        Picasso.get().load(currentCustom.getProductImage()).placeholder(R.drawable.shrimp_ditali).into(holder.thisProductImage);
        holder.thisProductName.setText(currentCustom.getProductName());
        holder.thisProductPrice.setText(currentCustom.getProductPrice());
    }

    public int getItemCount() {
        return customized.size();
    }
}

我把我的recyclerView放置在这个活动中。

public class BuildProduct extends AppCompatActivity {
    public final static ArrayList<CustomizeProduct> customized = new ArrayList<>();
    private RecyclerView recyclerView;
    private ProductAdapter myAdapter;
    private RecyclerView.LayoutManager layoutManager;
    private static String productImage, productPrice;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_build_product);

        buildCustom();
    }

    public void buildCustom(){
        recyclerView = findViewById(R.id.customList);
        recyclerView.setHasFixedSize(true);
        layoutManager = new LinearLayoutManager(this);

        final DatabaseReference ref = FirebaseDatabase.getInstance().getReference().child("MENIU");
        ref.addListenerForSingleValueEvent(new ValueEventListener(){
            public void onDataChange(DataSnapshot ds) {
                for (DataSnapshot menu : ds.getChildren()) {
                    String keys = menu.getKey();
                    String productName = (String) ds.child(keys).child("NUME_PRODUS").getValue();
                    if(productName.equals(checkout.thisProductName)){
                        productImage = ds.child(keys).child("IMAGINE").getValue(String.class);
                        Long price = (Long) ds.child(keys).child("PRET_PRODUS").getValue();
                        productPrice = String.valueOf(price);
                        Toast.makeText(getApplicationContext(), productImage + " " + productPrice, Toast.LENGTH_LONG).show();
                    }
                }
            }

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

            }
        });
        for(int i = 0; i < checkout.thisProductQty; i++) {
            customized.add(new CustomizeProduct(productImage,checkout.thisProductName, productPrice));
            myAdapter = new ProductAdapter(getApplicationContext(), customized);
        }
        recyclerView.setLayoutManager(layoutManager);
        recyclerView.setAdapter(myAdapter);
    }
}

产品名称是正确的，因为它是一个变量， 但图像和价格没有任何变化。这个 "for "循环的作用是在我的产品结账时创建尽可能多的cardViews，我怎样才能让它显示数据库中的图片和价格呢？

这是我的Firebase子结构。

Firebase Database

EDIT更新了代码。

public class CustomizeProduct {
    private String imagine;
    private String nume_produs;
    private String pret_produs;

    public CustomizeProduct(){}

    public CustomizeProduct(String imagine, String nume_produs, String pret_produs){
        this.imagine = imagine;
        this.nume_produs = nume_produs;
        this.pret_produs = pret_produs;
    }
    @PropertyName("IMAGINE")
    public String getIMAGINE() {
        return imagine;
    }
    @PropertyName("NUME_PRODUS")
    public String getNUME_PRODUS() {
        return nume_produs;
    }
    @PropertyName("PRET_PRODUS")
    public String getPRET_PRODUS() { return pret_produs; }

}

在onBindViewHolder中，

public void onBindViewHolder(ViewHolder holder, int position) {
        CustomizeProduct currentCustom = customized.get(position);
        Picasso.get().load(currentCustom.getIMAGINE()).placeholder(R.drawable.shrimp_ditali).into(holder.thisProductImage);
        holder.thisProductName.setText(currentCustom.getNUME_PRODUS());
        holder.thisProductPrice.setText(currentCustom.getPRET_PRODUS());
    }
java android firebase firebase-realtime-database
1个回答
0
投票

customized.add(new CustomizeProduct(productImage,checkout.thisProductName, productPrice));

你只能看到产品名称(checkout.thisProductName)，但不是产品图片& 价格，因为你用产品名称填充你的适配器，而Firebase在你的 onDataChange(DataSnapshot ds) 回调；在你的代码中没有任何线索，你如何建立产品名称(checkout.thisProductName)值。

现在，当你在主线程中构建适配器时，产品图片& 价格不显示，而firebase是在后台线程中隐式工作的，所以你需要将你的适配器同步到后台线程中，将构建recyclerView适配器的部分代码转移到firebase回调中，如下所示。

public void buildCustom(){
    recyclerView = findViewById(R.id.customList);
    recyclerView.setHasFixedSize(true);
    layoutManager = new LinearLayoutManager(this);

    final DatabaseReference ref = FirebaseDatabase.getInstance().getReference().child("MENIU");
    ref.addListenerForSingleValueEvent(new ValueEventListener(){
        public void onDataChange(DataSnapshot ds) {
            for (DataSnapshot menu : ds.getChildren()) {
                String keys = menu.getKey();
                String productName = (String) ds.child(keys).child("NUME_PRODUS").getValue();
                if(productName.equals(checkout.thisProductName)){
                    productImage = ds.child(keys).child("IMAGINE").getValue(String.class);
                    Long price = (Long) ds.child(keys).child("PRET_PRODUS").getValue();
                    productPrice = String.valueOf(price);
                    Toast.makeText(getApplicationContext(), productImage + " " + productPrice, Toast.LENGTH_LONG).show();
                }
            }

            // here you've received all Firebase data and can now build the recyclerView
            for(int i = 0; i < checkout.thisProductQty; i++) {
                customized.add(new CustomizeProduct(productImage,checkout.thisProductName, productPrice));
                myAdapter = new ProductAdapter(getApplicationContext(), customized);
            }
            recyclerView.setLayoutManager(layoutManager);
            recyclerView.setAdapter(myAdapter);

        }

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

        }
    });

}
0
投票

我想你可能还需要注释私有字段，因为SDK使用这些字段来实现 设置 数据库中的值。

public class CustomizeProduct {
    @PropertyName("IMAGINE")
    private String imagine;
    @PropertyName("NUME_PRODUS")
    private String nume_produs;
    @PropertyName("PRET_PRODUS")
    private String pret_produs;

    public CustomizeProduct(){}

    public CustomizeProduct(String imagine, String nume_produs, String pret_produs){
        this.imagine = imagine;
        this.nume_produs = nume_produs;
        this.pret_produs = pret_produs;
    }
    @PropertyName("IMAGINE")
    public String getIMAGINE() {
        return imagine;
    }
    @PropertyName("NUME_PRODUS")
    public String getNUME_PRODUS() {
        return nume_produs;
    }
    @PropertyName("PRET_PRODUS")
    public String getPRET_PRODUS() { return pret_produs; }
}

请注意，使用getters和setters是完全可选的，你也可以使用这个（短得多）的类来绑定到同一个JSON结构。

public class CustomizeProduct {
    @PropertyName("IMAGINE")
    public String imagine;

    @PropertyName("NUME_PRODUS")
    public String nume_produs;

    @PropertyName("PRET_PRODUS")
    public String pret_produs;
}
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