无法在 recycleview 中显示从 url 获取的 json 数据

Question

我刚开始学习android， 尝试一个有按钮的应用程序，点击button

（主活动）

，第二个活动

（第二个活动）

加载有cardview图像的加载，点击另一个活动

activity_swami

打开必须将数据从 url（json 格式）加载到 textview（CARDVIEW）中。但它显示空白活动。 显示本地静态数据。 我在

中有一个 recyclerview 代码

activity_recycle

我的文件是 swami.java

    package com.example.vinay.scroll;
import android.app.ProgressDialog;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.widget.Toast;
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;
import java.util.List;


public class swami extends AppCompatActivity {

//   private static final String URL_DATA="http://192.168.31.152/MyApi/index.php";
private static final String URL_DATA="https://vinayshirashyad.000webhostapp.com/index.php";
private RecyclerView recyclerView;
private RecyclerView.Adapter adapter;

private List<ActivitySwami> activitySwamiList;

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

recyclerView = (RecyclerView) findViewById(R.id.recycle);
recyclerView.setAdapter(adapter);
recyclerView.setLayoutManager(new LinearLayoutManager(getApplicationContext()));
recyclerView.setHasFixedSize(true);


activitySwamiList = new ArrayList<>();
loadRecyclerViewData();
}
private void loadRecyclerViewData(){

final ProgressDialog progressDialog = new ProgressDialog(this);
progressDialog.setMessage("Loading Data");
progressDialog.show();

StringRequest stringRequest = new StringRequest(Request.Method.GET,
URL_DATA,
new Response.Listener<String>() {
@Override
public void onResponse(String response) {
progressDialog.dismiss();

try {
JSONObject jsonObject = new JSONObject(response);
JSONArray array = jsonObject.getJSONArray("swami");


for(int i=0;i<array.length();i++) {
JSONObject o = array.getJSONObject(i);
ActivitySwami activitySwami = new ActivitySwami(
o.getString("name"), o.getString("description"))
}

adapter = new swamiAdapter(activitySwamiList,getApplicationContext());
recyclerView.setAdapter(adapter);

} catch (JSONException e) {
e.printStackTrace();
}


}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
progressDialog.dismiss();
Toast.makeText(getApplicationContext(),error.getMessage(),Toast.LENGTH_LONG).show();
}
});
RequestQueue requestQueue = Volley.newRequestQueue(this);
requestQueue.add(stringRequest);

}
}

适配器类 swamiAdapter.java

    package com.example.vinay.scroll;

import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import java.util.List;

/**
* Created by vinay on 3/16/2018.
*/

public class swamiAdapter extends RecyclerView.Adapter<swamiAdapter.ViewHolder> {

private List<ActivitySwami> activitySwamiList;
private Context context;

public swamiAdapter(List<ActivitySwami> activitySwamiList, Context context) {

this.activitySwamiList = activitySwamiList;
this.context = context;
}

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

@Override
public void onBindViewHolder(ViewHolder holder, int position) {
ActivitySwami activitySwami = activitySwamiList.get(position);

//  holder.id.setText(activitySwami.getId());

holder.name.setText(activitySwami.getName());
holder.desc.setText(activitySwami.getDesc());
}

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

public class ViewHolder extends  RecyclerView.ViewHolder {

//public TextView id;
public TextView name;
public TextView desc;

public ViewHolder(View itemView) {
super(itemView);
//  id = itemView.findViewById(R.id.id);
name = itemView.findViewById(R.id.name);
desc = itemView.findViewById(R.id.desc);
}
}
}

activity_recycle.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingTop="10dp"
android:paddingBottom="10dp"
android:paddingLeft="10dp"
android:paddingRight="10dp"
tools:context="com.example.vinay.scroll.swami">
<android.support.v7.widget.RecyclerView
android:id="@+id/recycle"
android:layout_width="match_parent"
android:layout_height="match_parent">
</android.support.v7.widget.RecyclerView>
</RelativeLayout>

activity_swami.xml

    <?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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="wrap_content"
tools:context="com.example.vinay.scroll.swami"
android:orientation="vertical">
<android.support.v7.widget.CardView
app:elevation="25dp"
android:clickable="true"
android:foreground="?android:attr/selectableItemBackground"
android:layout_width="match_parent"
android:layout_height="90dp"
android:layout_gravity="center"
android:layout_margin="5dp"
app:cardCornerRadius="15dp">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:padding="@dimen/cardview_default_elevation">
<TextView
android:id="@+id/name"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="name"/>
<TextView
android:id="@+id/desc"
android:layout_width="match_parent"
android:layout_height="200dp"
android:text="description"/>
</LinearLayout>
</android.support.v7.widget.CardView>
</LinearLayout>

Answer 1

您忘记在 activitySwamiList ArrayList 中添加数据

试试下面的代码

for(int i=0;i<array.length();i++) {
      JSONObject o = array.getJSONObject(i);
      ActivitySwami activitySwami = new ActivitySwami(
               o.getString("name"), o.getString("description"));
      activitySwamiList.add(activitySwami)
}

Answer 2

将数据添加到Arraylist

activitySwamiList.add(activitySwami)