如何使RecyclerView显示项目

我真的很难理解RecyclerView是如何工作的。我已经制作了适配器和它的主要代码，但它什么都没有显示。

我已经尝试了几件事，但都不起作用，因为我不知道自己在做什么。此外，我已经为它做了自定义布局，所以如果可能的话，我想使用

一点编辑：

我还检查了Postman中的php代码，看看这是否是问题所在，一切都很顺利，我得到了我需要的所有数据，所以问题出在android代码上。这是适配器：

package com.example.create4me;
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 org.w3c.dom.Text;
import java.util.ArrayList;
class RecyclerAdapter extends RecyclerView.Adapter<RecyclerAdapter.ViewHolder> {
private ArrayList<CardItem> data;
public class ViewHolder extends RecyclerView.ViewHolder{
public TextView title;
public TextView price;
public ImageView image;
public ViewHolder(View itemView){
super(itemView);
title = (TextView) itemView.findViewById(R.id.cardLayoutTitle);
price = (TextView) itemView.findViewById(R.id.cardLayoutPrice);
image = (ImageView) itemView.findViewById(R.id.cardLayoutImage);
}
}
public RecyclerAdapter(ArrayList<CardItem> arr){
data = arr;
}
@Override
public RecyclerAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
Context context = parent.getContext();
LayoutInflater inflater = LayoutInflater.from(context);
// Inflate the custom layout
View cardView = inflater.inflate(R.layout.cardlayout, parent, false);
// Return a new holder instance
ViewHolder viewHolder = new ViewHolder(cardView);
return viewHolder;
}
public void onBindViewHolder(RecyclerAdapter.ViewHolder holder, int pos){
CardItem item = data.get(pos);
TextView title = holder.title;
TextView price = holder.price;
ImageView image = holder.image;
title.setText(data.get(pos).getTitle());
price.setText(data.get(pos).getPrice());
/**
image.setImageBitmap(data.get(pos).getImage());
**/
}
public int getItemCount(){
return data.size();
}

}

这是主页片段：

package com.example.create4me;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
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;
public class Home extends Fragment {
TextView text;
RecyclerView container;
RecyclerAdapter adapter;
ArrayList<CardItem> arr = new ArrayList<>();
@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
container = view.findViewById(R.id.homeContainer);
adapter = new RecyclerAdapter(arr);
container.setAdapter(adapter);
container.setLayoutManager(new LinearLayoutManager(getContext()));
loaditems();
}
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState){
return inflater.inflate(R.layout.home, container, false);
}
void loaditems(){
String url = "http://192.168.108.2/createdb/GetAllOffers.php";
StringRequest stringRequest = new StringRequest(Request.Method.GET, url,
new Response.Listener<String>() {
@Override
public void onResponse(String response) {
try {
JSONArray jsonArray = new JSONArray(response);
JSONObject jsonResponse = jsonArray.getJSONObject(0);
JSONArray jsonArray_users = jsonResponse.getJSONArray("offers");
for (int i = 0; i < jsonArray_users.length(); i++) {
JSONObject jsonObject = jsonArray_users.getJSONObject(i);
arr.add(new CardItem(jsonObject.getString("title"),
jsonObject.getString("desc"),
jsonObject.getString("price"),
jsonObject.getString("madeby"),
jsonObject.getString("uuid")));
}
adapter.notifyDataSetChanged();
} catch (JSONException e) {
e.printStackTrace();
}
}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
text.setText(error.getMessage().toString());
}
});
RequestQueue requestQueue = Volley.newRequestQueue(getContext());
requestQueue.add(stringRequest);
}
}

这是CardItem类：

package com.example.create4me;
import android.content.Intent;
public class CardItem {
//private int mImageResource;
private String title, desc, price, madeby, uuid;
public CardItem(
String title,
String desc,
String price,
String madeby,
String uuid){
//this.mImageResource = image;
this.title = title;
this.desc = desc;
this.price = price;
this.madeby = madeby;
this.uuid = uuid;
}
public String getUuid(){
return this.uuid;
}
/**
public int getImage(){
return this.mImageResource;
}
**/
public String getTitle(){
return this.title;
}
public String getDesc(){
return this.desc;
}
public String getPrice(){
return this.price;
}
public String getMadeby(){return this.madeby;}
}