这是一个有效的 JSON 对象吗？如果是，那么我如何迭代以获取所有值

Question

我收到来自服务器的有效响应 JSON。

{"Avg":[{"avg":3,"rcid":"ww44sd"},{"avg":4,"rcid":"ww24hj"},{"avg":3,"rcid":"ww36hd"},{"avg":4,"rcid":"ww89yx"},{"avg":3,"rcid":"ww64tf"},{"avg":4,"rcid":"ww76py"}]}

我写了下面的代码，但我不明白为什么这不是 JSON对象。 Logcat 显示此错误 FATAL EXCEPTION: main java.lang.ClassCastException: java.util.HashMap cannot be cast to org.json.JSONObject

ParseCloud.callFunctionInBackground("avgfunc", params, new FunctionCallback<JSONObject>() {
public void done(JSONObject response, ParseException e) {
            if (e == null) { 

try {
      JSONObject jsonRoot = new JSONObject(response);
      JSONArray jsonarr = jsonRoot.getJSONArray("Avg");
           for (int i = 0; i < jsonarr.length(); i++) {
               JSONObject json = jsonarr.getJSONObject(i);
               //do some processing...
               }
      } catch (JSONException e1) {
                    e1.printStackTrace();
      }

在我的 CloudCode 中，我正在生成这样的响应

Parse.Cloud.define("avgfunc", function(request, response) {
  var idlist = request.params.someids;
  var _ = require("underscore");

  var newlist = {"Avg":[]}; //This is to initialize & later push

   ......
  _.each(idlist,function(categoryid){
   ......
  query.find({
  success: function(results) {
   if(results.length==0){
    console.log("No row found");
    }
    //some more processing of data & then finally push

    newlist.Avg.push({              //& this
       "avg":somevalue,
       "rcid":somevalue
     });
    }
    if(counter == idlist.length)
    {
      response.success(newlist); //this sends the response as shown above
    } 
  },
  error: function() {
    response.error("error.");
  }
 });
});

});

所以我想知道如何构造适当的 JSON 对象，以便稍后在 android 中迭代各个项目。

编辑：堆栈跟踪

 2937-2937/com.muffin.testapp E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.ClassCastException: java.util.HashMap cannot be cast to org.json.JSONObject
        at com.muffin.testapp.CollinfoActivity.done(CollinfoActivity.java:133)
        at com.parse.ParseTaskUtils.run(ParseTaskUtils.java:107)
        at android.os.Handler.handleCallback(Handler.java:605)
        at android.os.Handler.dispatchMessage(Handler.java:92)
        at android.os.Looper.loop(Looper.java:137)
        at android.app.ActivityThread.main(ActivityThread.java:4424)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:511)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
        at dalvik.system.NativeStart.main(Native Method)

第 133 行是 ParseCloud.callFunctionInBackground("getAVGrating", params, new FunctionCallback<JSONObject>() {

Answer 1

json 字符串似乎是合法的。这是一些解析它的代码。

我正在使用从这里下载的 json-simple-1.1.1.jar： https://code.google.com/p/json-simple/downloads/detail?name=json-simple-1.1.1.jar&can=2&q=

import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;

public class JsonExample {

    public static void main(String[] args) throws Exception {
        System.out.println("Starting example...");
        String str = "{\"Avg\":[{\"avg\":3,\"rcid\":\"ww44sd\"},{\"avg\":4,\"rcid\":\"ww24hj\"},{\"avg\":3,\"rcid\":\"ww36hd\"},{\"avg\":4,\"rcid\":\"ww89yx\"},{\"avg\":3,\"rcid\":\"ww64tf\"},{\"avg\":4,\"rcid\":\"ww76py\"}]}";
        JSONParser parser = new JSONParser();
        Object obj = parser.parse(str);
        JSONObject json = (JSONObject) obj;
        Object avgObj = json.get("Avg");
        JSONArray avgArray = (JSONArray) avgObj;
        System.out.println("JSON Strings for averages:");
        for(int i=0;i<avgArray.size();i++) {
            JSONObject current = (JSONObject)avgArray.get(i);
            System.out.println("\t" + current);
        }
        System.out.println("Averages:");
        for(int i=0;i<avgArray.size();i++) {
            JSONObject current = (JSONObject)avgArray.get(i);
            System.out.println("\tAvergage: " + current.get("avg"));
        }
        System.out.println("Done.");
    }

}

编辑：这是输出。

Starting example...
JSON Strings for averages:
    {"avg":3,"rcid":"ww44sd"}
    {"avg":4,"rcid":"ww24hj"}
    {"avg":3,"rcid":"ww36hd"}
    {"avg":4,"rcid":"ww89yx"}
    {"avg":3,"rcid":"ww64tf"}
    {"avg":4,"rcid":"ww76py"}
Averages:
    Avergage: 3
    Avergage: 4
    Avergage: 3
    Avergage: 4
    Avergage: 3
    Avergage: 4
Done.

Answer 2

只是运行遇到了同样的问题。您的 JSON 没有任何问题，只是 callFunctionInBackground 函数将所有 JSONArray 解析为 List<>，并将 JSONObject 解析为 Hashmap<>。因此，您实际上得到的不是 JSONObject，而是 Hashmap<String, Object>.

这是一个有效的 JSON 对象吗？如果是，那么我如何迭代以获取所有值

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