Java 无法将Firebase数据库中的数据检索到我的Android应用程序中

我已将数据存储到Firebase数据库中，但无法检索一组数据。
并且图像没有显示。我只能看到

添加到购物车的按钮和
优雅按钮
，但它显示了在
活动_产品_类别
中写入的文本，即它静态显示产品价格、产品名称、产品描述，并且不会替换为数据库中的实际值

下面我已附加Firebase结构。请帮忙

ProductsDetailsActivity.java:

 package com.example.giftngame;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

import com.cepheuen.elegantnumberbutton.view.ElegantNumberButton;
import com.example.giftngame.Model.Products;
import com.example.giftngame.Prevalent.Prevalent;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.android.material.floatingactionbutton.FloatingActionButton;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.ValueEventListener;
import com.squareup.picasso.Picasso;

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.HashMap;

public class ProductDetailsActivity extends AppCompatActivity
{
    private Button addToCartButton;
    private ImageView productImage;
    private ElegantNumberButton numberButton;
    private TextView productPrice,productDescription,productName;
    private String productID="";

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

        productID = getIntent().getStringExtra("pid");

        addToCartButton = (Button) findViewById(R.id.pd_add_to_cart_button);
        numberButton = (ElegantNumberButton) findViewById(R.id.number_btn);
        productImage = (ImageView) findViewById(R.id.product_image_details);
        productPrice = (TextView) findViewById(R.id.product_price);
        productDescription = (TextView) findViewById(R.id.product_description_details);
        productName = (TextView) findViewById(R.id.product_name_details);

        getProductDetails(productID);
    }

    private void getProductDetails(String productID)
    {
        final DatabaseReference productsRef= FirebaseDatabase.getInstance().getReference().child("Products");
        productsRef.child("Products").child(productID).addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange( DataSnapshot dataSnapshot)
            {
                if(dataSnapshot.exists())
                {
                    Products products=dataSnapshot.getValue(Products.class);

                    productName.setText(products.getPname());
                    productDescription.setText(products.getDescription());
                    productPrice.setText(products.getPrice());
                    Picasso.get().load(products.getImage()).into(productImage);

                }
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        });

    }

}

package com.example.giftngame.Model;

public class Products
{
    private String pid,pname,price,description,image,category,date,time;


    public Products()
    {

    }

    public Products(String pname, String description, String price, String image, String category, String pid, String date, String time)
    {
        this.pname = pname;
        this.description = description;
        this.price = price;
        this.image = image;
        this.category = category;
        this.pid = pid;
        this.date = date;
        this.time = time;
    }

    public String getPname() {
        return pname;
    }

    public void setPname(String pname) {
        this.pname = pname;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public String getPrice() {
        return price;
    }

    public void setPrice(String price) {
        this.price = price;
    }

    public String  getImage() {
        return image;
    }

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

    public String getCategory() {
        return category;
    }

    public void setCategory(String category) {
        this.category = category;
    }

    public String getPid() {
        return pid;
    }

    public void setPid(String pid) {
        this.pid = pid;
    }

    public String getDate() {
        return date;
    }

    public void setDate(String date) {
        this.date = date;
    }

    public String getTime() {
        return time;
    }

    public void setTime(String time) {
        this.time = time;
    }
}

Products.java:

 package com.example.giftngame;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

import com.cepheuen.elegantnumberbutton.view.ElegantNumberButton;
import com.example.giftngame.Model.Products;
import com.example.giftngame.Prevalent.Prevalent;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.android.material.floatingactionbutton.FloatingActionButton;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.ValueEventListener;
import com.squareup.picasso.Picasso;

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.HashMap;

public class ProductDetailsActivity extends AppCompatActivity
{
    private Button addToCartButton;
    private ImageView productImage;
    private ElegantNumberButton numberButton;
    private TextView productPrice,productDescription,productName;
    private String productID="";

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

        productID = getIntent().getStringExtra("pid");

        addToCartButton = (Button) findViewById(R.id.pd_add_to_cart_button);
        numberButton = (ElegantNumberButton) findViewById(R.id.number_btn);
        productImage = (ImageView) findViewById(R.id.product_image_details);
        productPrice = (TextView) findViewById(R.id.product_price);
        productDescription = (TextView) findViewById(R.id.product_description_details);
        productName = (TextView) findViewById(R.id.product_name_details);

        getProductDetails(productID);
    }

    private void getProductDetails(String productID)
    {
        final DatabaseReference productsRef= FirebaseDatabase.getInstance().getReference().child("Products");
        productsRef.child("Products").child(productID).addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange( DataSnapshot dataSnapshot)
            {
                if(dataSnapshot.exists())
                {
                    Products products=dataSnapshot.getValue(Products.class);

                    productName.setText(products.getPname());
                    productDescription.setText(products.getDescription());
                    productPrice.setText(products.getPrice());
                    Picasso.get().load(products.getImage()).into(productImage);

                }
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        });

    }

}

package com.example.giftngame.Model;

public class Products
{
    private String pid,pname,price,description,image,category,date,time;


    public Products()
    {

    }

    public Products(String pname, String description, String price, String image, String category, String pid, String date, String time)
    {
        this.pname = pname;
        this.description = description;
        this.price = price;
        this.image = image;
        this.category = category;
        this.pid = pid;
        this.date = date;
        this.time = time;
    }

    public String getPname() {
        return pname;
    }

    public void setPname(String pname) {
        this.pname = pname;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public String getPrice() {
        return price;
    }

    public void setPrice(String price) {
        this.price = price;
    }

    public String  getImage() {
        return image;
    }

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

    public String getCategory() {
        return category;
    }

    public void setCategory(String category) {
        this.category = category;
    }

    public String getPid() {
        return pid;
    }

    public void setPid(String pid) {
        this.pid = pid;
    }

    public String getDate() {
        return date;
    }

    public void setDate(String date) {
        this.date = date;
    }

    public String getTime() {
        return time;
    }

    public void setTime(String time) {
        this.time = time;
    }
}

这是项目的详细说明之一

根据您的firebase结构产品，子项是一个itemtype（Keychain），它具有类似于item1、item2的子项。您没有正确查询firebase数据库。应该是

 DatabaseReference productsRef= FirebaseDatabase.getInstance().getReference().child("Products");
 productsRef.child(itemType(like Keychain)).child(productID).addValueEventListener

itemType（Keychain）是固定的还是动态的？如果是动态的，则代码将不同。让我知道。
您使用了两次那里的儿童
产品。这是错误的

final DatabaseReference productsRef= FirebaseDatabase.getInstance().getReference().child("Products");
productsRef.child("Products").child(productID).addValueEventListener(new ValueEventListener() {...

我知道您想显示产品的详细信息。您可以对您的条件使用查询。试试这个：-

private void getProductDetails(final String productID)
{
    final DatabaseReference productsRef= FirebaseDatabase.getInstance().getReference().child("Products");
    final Query queryProductDetail = productRef.orderByChild("pid").equalTo(productID);
    productsRef.child("Products").child(productID).addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange( DataSnapshot dataSnapshot)
        {
            if(dataSnapshot.exists())
            {
                Products products = dataSnapshot.getValue(Products.class);
            productName.setText(products.getPname());
            productDescription.setText(products.getDescription());
            productPrice.setText(products.getPrice());
            Picasso.get().load(products.getImage()).into(productImage);

            }
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
   });
}

钥匙链项目是众多项目中的一项，共有8项（钥匙链、马克杯、镇纸、笔架、香水、相框、泰迪熊、风铃）这些都是产品的孩子ProductDetailsActivity.java被设置为对所有人来说都是通用的。所以我没有选择特别写itemType Keychain你是如何开始ProductDetails活动的我不明白你的问题你是如何开始ProductDetailsActivity活动的。这是你的主要活动吗？