RecyclerView未在Android Studio 3.5.3中显示项目

我试图将数据库从

Mysql

显示到

RecylerView

，但应用程序没有显示任何内容。logcat中没有

错误

。我从谷歌那里得到了这个教程，并且原始的项目工作得很好。我只是学习在代码中实现

build.gradle:

implementation "androidx.recyclerview:recyclerview-selection:1.1.0-beta01"
implementation 'com.android.volley:volley:1.1.1'
implementation 'com.github.bumptech.glide:glide:4.8.0'

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.skripsans.MainActivity">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recylcerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:layout_editor_absoluteX="745dp"
        tools:layout_editor_absoluteY="-51dp"
        android:visibility="visible">
    </androidx.recyclerview.widget.RecyclerView>

</RelativeLayout>

以下是activity\u main.XML的XML代码：

implementation "androidx.recyclerview:recyclerview-selection:1.1.0-beta01"
implementation 'com.android.volley:volley:1.1.1'
implementation 'com.github.bumptech.glide:glide:4.8.0'

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.skripsans.MainActivity">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recylcerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:layout_editor_absoluteX="745dp"
        tools:layout_editor_absoluteY="-51dp"
        android:visibility="visible">
    </androidx.recyclerview.widget.RecyclerView>

</RelativeLayout>

ProductsAdapter.java

package com.example.skripsans;

/**
 * Created by Belal on 10/18/2017.
 */

public class Product {
    private int id;
    private String title;
    private String shortdesc;
    private double rating;
    private double price;
    private String image;

    public Product(int id, String title, String shortdesc, double rating, double price, String image) {
        this.id = id;
        this.title = title;
        this.shortdesc = shortdesc;
        this.rating = rating;
        this.price = price;
        this.image = image;
    }

    public int getId() {
        return id;
    }

    public String getTitle() {
        return title;
    }

    public String getShortdesc() {
        return shortdesc;
    }

    public double getRating() {
        return rating;
    }

    public double getPrice() {
        return price;
    }

    public String getImage() {
        return image;
    }
}

package com.example.skripsans;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import androidx.recyclerview.widget.RecyclerView;


import com.bumptech.glide.Glide;

import java.util.List;

/**
 * Created by Belal on 10/18/2017.
 */

public class ProductsAdapter extends RecyclerView.Adapter<ProductsAdapter.ProductViewHolder> {


    private Context mCtx;
    private List<Product> productList;

    public ProductsAdapter(Context mCtx, List<Product> productList) {
        this.mCtx = mCtx;
        this.productList = productList;
    }

    @Override
    public ProductViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        LayoutInflater inflater = LayoutInflater.from(mCtx);
        View view = inflater.inflate(R.layout.product_list, null);
        return new ProductViewHolder(view);
    }

    @Override
    public void onBindViewHolder(ProductViewHolder holder, int position) {
        Product product = productList.get(position);

        //loading the image
        Glide.with(mCtx)
                .load(product.getImage())
                .into(holder.imageView);

        holder.textViewTitle.setText(product.getTitle());
        holder.textViewShortDesc.setText(product.getShortdesc());
        holder.textViewRating.setText(String.valueOf(product.getRating()));
        holder.textViewPrice.setText(String.valueOf(product.getPrice()));
    }

    @Override
    public int getItemCount() {
        return productList.size();
    }

    class ProductViewHolder extends RecyclerView.ViewHolder {

        TextView textViewTitle, textViewShortDesc, textViewRating, textViewPrice;
        ImageView imageView;

        public ProductViewHolder(View itemView) {
            super(itemView);

            textViewTitle = itemView.findViewById(R.id.textViewTitle);
            textViewShortDesc = itemView.findViewById(R.id.textViewShortDesc);
            textViewRating = itemView.findViewById(R.id.textViewRating);
            textViewPrice = itemView.findViewById(R.id.textViewPrice);
            imageView = itemView.findViewById(R.id.imageView);
        }
    }
}

package com.example.skripsans;

import android.os.Bundle;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import com.android.volley.Request;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.android.volley.toolbox.Volley;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    //this is the JSON Data URL
    //make sure you are using the correct ip else it will not work
    private static final String URL_PRODUCTS = "http://192.168.100.10/Api.php";

    //a list to store all the products
    List<Product> productList;

    //the recyclerview
    RecyclerView recyclerView;


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

        //getting the recyclerview from xml
        recyclerView = findViewById(R.id.recylcerView);
        recyclerView.setHasFixedSize(true);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));

        //initializing the productlist
        productList = new ArrayList<>();

        //this method will fetch and parse json
        //to display it in recyclerview
        loadProducts();
    }

    private void loadProducts() {

        /*
         * Creating a String Request
         * The request type is GET defined by first parameter
         * The URL is defined in the second parameter
         * Then we have a Response Listener and a Error Listener
         * In response listener we will get the JSON response as a String
         * */
        StringRequest stringRequest = new StringRequest(Request.Method.GET, URL_PRODUCTS,
                new Response.Listener<String>() {
                    @Override
                    public void onResponse(String response) {
                        try {
                            //converting the string to json array object
                            JSONArray array = new JSONArray(response);

                            //traversing through all the object
                            for (int i = 0; i < array.length(); i++) {

                                //getting product object from json array
                                JSONObject product = array.getJSONObject(i);

                                //adding the product to product list
                                productList.add(new Product(
                                        product.getInt("id"),
                                        product.getString("title"),
                                        product.getString("shortdesc"),
                                        product.getDouble("rating"),
                                        product.getDouble("price"),
                                        product.getString("image")
                                ));
                            }

                            //creating adapter object and setting it to recyclerview
                            ProductsAdapter adapter = new ProductsAdapter(MainActivity.this, productList);
                            recyclerView.setAdapter(adapter);
                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                    }
                },
                new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {

                    }
                });

        //adding our stringrequest to queue
        Volley.newRequestQueue(this).add(stringRequest);
    }
}

package com.example.skripsans；
导入android.content.Context；
导入android.view.LayoutInflater；
导入android.view.view；
导入android.view.ViewGroup；
导入android.widget.ImageView；
导入android.widget.TextView；
导入androidx.recyclerview.widget.recyclerview；
导入com.bumptech.glide.glide；
导入java.util.List；
/**
*由Belal于2017年10月18日创建。
*/
公共类ProductsAdapter扩展了RecyclerView.Adapter{
私有上下文mCtx；
私有列表产品列表；
公共产品适配器（上下文mCtx，列表productList）{
this.mCtx=mCtx；
this.productList=productList；
}
@凌驾
公共产品ViewHolder onCreateViewHolder（视图组父级，int-viewType）{
LayoutFlater充气机=LayoutFlater.from（mCtx）；
视图=充气机。充气（R.layout.product\u列表，空）；
返回新的ProductViewHolder（视图）；
}
@凌驾
BindViewHolder上的公共无效（ProductViewHolder，int位置）{
产品=产品列表。获取（位置）；
//加载图像
滑翔带（mCtx）
.load（product.getImage（））
.插入（支架.图像视图）；
holder.textViewTitle.setText（product.getTitle（））；
holder.textViewShortDesc.setText（product.getShortdesc（））；
holder.textViewRating.setText（String.valueOf（product.getRating（））；
holder.textViewPrice.setText（String.valueOf（product.getPrice（））；
}
@凌驾
public int getItemCount（）{
返回productList.size（）；
}
类ProductViewHolder扩展了RecyclerView.ViewHolder{
TextView textViewTitle、textViewShortDesc、textViewRating、textViewPrice；
图像视图图像视图；
公共产品视图持有者（视图项视图）{
超级（项目视图）；
textViewTitle=itemView.findViewById（R.id.textViewTitle）；
textViewShortDesc=itemView.findViewById（R.id.textViewShortDesc）；
textViewRating=itemView.findViewById（R.id.textViewRating）；
textViewPrice=itemView.findViewById（R.id.textViewPrice）；
imageView=itemView.findViewById（R.id.imageView）；
}
}
}

MainActivity.java

package com.example.skripsans;

/**
 * Created by Belal on 10/18/2017.
 */

public class Product {
    private int id;
    private String title;
    private String shortdesc;
    private double rating;
    private double price;
    private String image;

    public Product(int id, String title, String shortdesc, double rating, double price, String image) {
        this.id = id;
        this.title = title;
        this.shortdesc = shortdesc;
        this.rating = rating;
        this.price = price;
        this.image = image;
    }

    public int getId() {
        return id;
    }

    public String getTitle() {
        return title;
    }

    public String getShortdesc() {
        return shortdesc;
    }

    public double getRating() {
        return rating;
    }

    public double getPrice() {
        return price;
    }

    public String getImage() {
        return image;
    }
}

package com.example.skripsans;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import androidx.recyclerview.widget.RecyclerView;


import com.bumptech.glide.Glide;

import java.util.List;

/**
 * Created by Belal on 10/18/2017.
 */

public class ProductsAdapter extends RecyclerView.Adapter<ProductsAdapter.ProductViewHolder> {


    private Context mCtx;
    private List<Product> productList;

    public ProductsAdapter(Context mCtx, List<Product> productList) {
        this.mCtx = mCtx;
        this.productList = productList;
    }

    @Override
    public ProductViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        LayoutInflater inflater = LayoutInflater.from(mCtx);
        View view = inflater.inflate(R.layout.product_list, null);
        return new ProductViewHolder(view);
    }

    @Override
    public void onBindViewHolder(ProductViewHolder holder, int position) {
        Product product = productList.get(position);

        //loading the image
        Glide.with(mCtx)
                .load(product.getImage())
                .into(holder.imageView);

        holder.textViewTitle.setText(product.getTitle());
        holder.textViewShortDesc.setText(product.getShortdesc());
        holder.textViewRating.setText(String.valueOf(product.getRating()));
        holder.textViewPrice.setText(String.valueOf(product.getPrice()));
    }

    @Override
    public int getItemCount() {
        return productList.size();
    }

    class ProductViewHolder extends RecyclerView.ViewHolder {

        TextView textViewTitle, textViewShortDesc, textViewRating, textViewPrice;
        ImageView imageView;

        public ProductViewHolder(View itemView) {
            super(itemView);

            textViewTitle = itemView.findViewById(R.id.textViewTitle);
            textViewShortDesc = itemView.findViewById(R.id.textViewShortDesc);
            textViewRating = itemView.findViewById(R.id.textViewRating);
            textViewPrice = itemView.findViewById(R.id.textViewPrice);
            imageView = itemView.findViewById(R.id.imageView);
        }
    }
}

package com.example.skripsans;

import android.os.Bundle;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import com.android.volley.Request;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.android.volley.toolbox.Volley;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    //this is the JSON Data URL
    //make sure you are using the correct ip else it will not work
    private static final String URL_PRODUCTS = "http://192.168.100.10/Api.php";

    //a list to store all the products
    List<Product> productList;

    //the recyclerview
    RecyclerView recyclerView;


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

        //getting the recyclerview from xml
        recyclerView = findViewById(R.id.recylcerView);
        recyclerView.setHasFixedSize(true);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));

        //initializing the productlist
        productList = new ArrayList<>();

        //this method will fetch and parse json
        //to display it in recyclerview
        loadProducts();
    }

    private void loadProducts() {

        /*
         * Creating a String Request
         * The request type is GET defined by first parameter
         * The URL is defined in the second parameter
         * Then we have a Response Listener and a Error Listener
         * In response listener we will get the JSON response as a String
         * */
        StringRequest stringRequest = new StringRequest(Request.Method.GET, URL_PRODUCTS,
                new Response.Listener<String>() {
                    @Override
                    public void onResponse(String response) {
                        try {
                            //converting the string to json array object
                            JSONArray array = new JSONArray(response);

                            //traversing through all the object
                            for (int i = 0; i < array.length(); i++) {

                                //getting product object from json array
                                JSONObject product = array.getJSONObject(i);

                                //adding the product to product list
                                productList.add(new Product(
                                        product.getInt("id"),
                                        product.getString("title"),
                                        product.getString("shortdesc"),
                                        product.getDouble("rating"),
                                        product.getDouble("price"),
                                        product.getString("image")
                                ));
                            }

                            //creating adapter object and setting it to recyclerview
                            ProductsAdapter adapter = new ProductsAdapter(MainActivity.this, productList);
                            recyclerView.setAdapter(adapter);
                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                    }
                },
                new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {

                    }
                });

        //adding our stringrequest to queue
        Volley.newRequestQueue(this).add(stringRequest);
    }
}

package com.example.skripsans；
导入android.os.Bundle；
导入androidx.appcompat.app.appcompat活动；
导入androidx.recyclerview.widget.LinearLayoutManager；
导入androidx.recyclerview.widget.recyclerview；
导入com.android.volley.Request；
导入com.android.volley.Response；
导入com.android.volley.VolleyError；
导入com.android.volley.toolbox.StringRequest；
导入com.android.volley.toolbox.volley；
导入org.json.JSONArray；
导入org.json.JSONException；
导入org.json.JSONObject；
导入java.util.ArrayList；
导入java.util.List；
公共类MainActivity扩展了AppCompatActivity{
//这是JSON数据URL
//确保您使用的是正确的ip，否则它将无法工作
私有静态最终字符串URL_PRODUCTS=”http://192.168.100.10/Api.php";
//存储所有产品的列表
列出产品清单；
//回收视图
回收视图回收视图；
@凌驾
创建时受保护的void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setContentView（R.layout.activity_main）；
//从xml获取recyclerview
recyclerView=findViewById（R.id.recylcerView）；
recyclerView.setHasFixedSize（true）；
recyclerView.setLayoutManager（新的LinearLayoutManager（本））；
//初始化产品列表
productList=新的ArrayList（）；
//此方法将获取并解析json
//要在recyclerview中显示它
loadProducts（）；
}
私有void loadProducts（）{
/*
*创建字符串请求
*请求类型由第一个参数定义
*URL在第二个参数中定义
*然后我们有一个响应侦听器和一个错误侦听器
*在response listener中，我们将以字符串形式获得JSON响应
* */
StringRequest StringRequest=新的StringRequest（Request.Method.GET、URL\u产品、，
新的Response.Listener（）{
@凌驾
公共void onResponse（字符串响应）{
试一试{
//将字符串转换为json数组对象
JSONArray数组=新的JSONArray（响应）；
//遍历所有对象
对于（int i=0；i