Android 从JSON web服务加载数据并在列表视图中显示

我正在尝试从JSON web服务加载数据并在列表视图中显示它，这是我第一次使用JSON，我还是初学者，所以任何人都请告诉我问题出在哪里

package com.androidhive.jsonparsing;

import java.util.ArrayList;
import java.util.HashMap;

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

import android.app.ListActivity;
import android.os.Bundle;
import android.widget.ListAdapter;
import android.widget.SimpleAdapter;

public class AndroidJSONParsingActivity extends ListActivity {

    // url to make request
    private static String url = "my url";

    // JSON Node names
     String TAG_CONTACTS = "TAG_CONTACTS";
     String Id = "Id";
     String DoctorName = "DoctorName";
     String ImageName = "ImageName";


    // contacts JSONArray
    JSONArray Doctors = null;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        // Hashmap for ListView
        ArrayList<HashMap<String, String>> contactList = new ArrayList<HashMap<String, String>>();

        // Creating JSON Parser instance
        JSONParser jParser = new JSONParser();

        // getting JSON string from URL
        JSONObject json = jParser.getJSONFromUrl(url);

        try {
            // Getting Array of Contacts
            Doctors = json.getJSONArray(TAG_CONTACTS);

            // looping through All Contacts
            for(int i = 0; i < Doctors.length(); i++){
                JSONObject c = Doctors.getJSONObject(i);

                // Storing each json item in variable
//               String Id =  c.getString("Id");
//               String DoctorName =  c.getString("DoctorName");
//               String ImageName =  c.getString("ImageName");
//          

                // creating new HashMap
                HashMap<String, String> map = new HashMap<String, String>();

                // adding each child node to HashMap key => value
                map.put("Id", c.getString("Id"));
                map.put("DoctorName", c.getString("DoctorName"));
                map.put("ImageName", c.getString("ImageName"));

                // adding HashList to ArrayList
                contactList.add(map);
            }
        } catch (JSONException e) {
            e.printStackTrace();
        }


        /**
         * Updating parsed JSON data into ListView
         * */
        ListAdapter adapter = new SimpleAdapter(this, contactList,
                R.layout.list_item,
                new String[] { DoctorName, ImageName }, new int[] {
                        R.id.name, R.id.image });

        setListAdapter(adapter);


    }

}

当我运行它时，它会给我这个警告

12-13 12:41:57.052: W/System.err(542): org.json.JSONException: No value for TAG_CONTACTS
12-13 12:41:57.052: W/System.err(542):  at org.json.JSONObject.get(JSONObject.java:354)
12-13 12:41:57.052: W/System.err(542):  at org.json.JSONObject.getJSONArray(JSONObject.java:544)
12-13 12:41:57.052: W/System.err(542):  at com.androidhive.jsonparsing.AndroidJSONParsingActivity.onCreate(AndroidJSONParsingActivity.java:56)
12-13 12:41:57.063: W/System.err(542):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
12-13 12:41:57.063: W/System.err(542):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
12-13 12:41:57.063: W/System.err(542):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
12-13 12:41:57.063: W/System.err(542):  at android.app.ActivityThread.access$1500(ActivityThread.java:117)
12-13 12:41:57.063: W/System.err(542):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
12-13 12:41:57.063: W/System.err(542):  at android.os.Handler.dispatchMessage(Handler.java:99)
12-13 12:41:57.072: W/System.err(542):  at android.os.Looper.loop(Looper.java:123)
12-13 12:41:57.072: W/System.err(542):  at android.app.ActivityThread.main(ActivityThread.java:3683)
12-13 12:41:57.072: W/System.err(542):  at java.lang.reflect.Method.invokeNative(Native Method)
12-13 12:41:57.072: W/System.err(542):  at java.lang.reflect.Method.invoke(Method.java:507)
12-13 12:41:57.072: W/System.err(542):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)

---

它会打开一个空屏幕！问题是什么？

您为JSON数组传递了错误的名称

org.json.JSONException:TAG_联系人没有值

应该是：

// Getting Array of Contacts
Doctors = json.getJSONArray("Doctors");

---

我认为在进行解析检查之前，Json解析标记中会出现错误

if(jsonObject.has("TAG_CONTACTS")){
Doctors = json.getJSONArray(TAG_CONTACTS);
}

---

并检查您使用的所有相关密钥和您得到的响应，这可能会帮助您

您的错误表示您的json没有任何名为TAG_CONTACTS的数组

if(jsonObject.has("TAG_CONTACTS")){
Doctors = json.getJSONArray(TAG_CONTACTS);
}