siting lin siting lin - 1 month ago 8
JSON Question

Android Json data parsing is ''[]'',Data parsing failed

Recently, I tried to code a list of linkman. I want to obtaining local data file(City.json) and parsing into

listView
. However ,the data from
JsonObject
always null. Help me please. I'm a Newbie. Thanks in advance.
the code under:

City.json

{
// "state": 1,
"datas": [
{
"id": "820",
"name": "安阳",
"sortKey": "A"
},
{
"id": "68",
"name": "安庆",
"sortKey": "A"
},
{
"id": "1269",
"name": "鞍山",
"sortKey": "A"
},
{
"id": "22",
"name": "蚌埠",
"sortKey": "B"
},
{
"id": "1372",
"name": "包头",
"sortKey": "B"
},
{
"id": "2419",
"name": "北京",
"sortKey": "B"
},
{
"id": "649",
"name": "保定",
"sortKey": "B"
},
{
"id": "1492",
"name": "宝鸡",
"sortKey": "B"
},
{
"id": "2419",
"name": "北京",
"sortKey": "B"
},
{
"id": "649",
"name": "保定",
"sortKey": "B"
},
{
"id": "1492",
"name": "宝鸡",
"sortKey": "B"
},
{
"id": "2419",
"name": "北京",
"sortKey": "B"
},
{
"id": "649",
"name": "保定",
"sortKey": "B"
},
{
"id": "1492",
"name": "宝鸡",
"sortKey": "B"
},
{
"id": "2419",
"name": "北京",
"sortKey": "B"
},
{
"id": "649",
"name": "保定",
"sortKey": "B"
},
{
"id": "1492",
"name": "宝鸡",
"sortKey": "B"
}
]

}


AppFileReader.java

package me.sitinglin.administrator.wecharlinkmantest;

import android.content.Context;
import android.content.res.AssetManager;
import android.util.Log;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import org.json.JSONTokener;

/**
* Created by Administrator on 2016/10/12.
*/

public class AppJsonFileReader {

public static String getJson(Context context, String fileName){
StringBuilder builder = new StringBuilder();
AssetManager manager = context.getAssets();
try {
InputStream stream = manager.open(fileName);
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(stream));
String line = null;
while((line = bufferedReader.readLine())!=null){
builder.append(line);
}
} catch (IOException e) {
e.printStackTrace();
}
// Log.i("abc", builder.toString());
return builder.toString();
}
public static List<City> setData(String str){
List<City> list = new ArrayList<>();
City city ;
try {
JSONObject result = new JSONObject(str);
JSONArray array = result.getJSONArray("datas");
// JSONArray array =new JSONArray(result);

int len = array.length();
Log.i("len", array.toString());
for (int i = 0; i <len ; i++) {
JSONObject object = array.optJSONObject(i);
city = new City();
city.setId(object.optString("id"));
city.setName(object.optString("name"));
city.setSortKey(object.optString("sortKey"));
list.add(city);
}
} catch (JSONException e) {
e.printStackTrace();
}
Log.i("lll", list.toString());
return list;
}
}


this my context of logcat

enter image description here

Answer

You should go with following code :

JSONObject jobj  = new JSONObject(str);

if(jobj.has("datas")){    
    JSONArray jsonArray = jobj.getJSONArray("datas");
    List<City> list = new ArrayList<>();

    for (int i = 0; i < jsonArray.length(); i++) {
        JSONObject jdataObj = jsonArray.getJSONObject(i);    
        City city = new City();
        city.setId(jdataObj.getString("id"));
        city.setName(jdataObj.getString("name"));
        city.setSortKey(jdataObj.getString("sortKey"));
        list.add(city);
    }
} else {
    Log.e("Json","Json has no datas key.")
}

Hope this will help you.

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