java没有获得内部arraylist的完美价值

Question

courseName名称很清楚，我不能在模型类中输入任何值

private static List<Country> countries =  new ArrayList<>();
private ArrayList<String> courseName = new ArrayList<>();
JSONArray datalist = data.optJSONArray("data_list");
for (int i = 0; i < datalist.length(); i++) {
    JSONObject jsonObject = datalist.getJSONObject(i);
    /*strTitle.add(jsonObject.optString("cat_name_lan1"));
    courceidtitle.add(jsonObject.optString("cat_id"));
    courseName.clear();*/
    strTitle = jsonObject.optString("cat_name_lan1");

    JSONArray courseArray = jsonObject.optJSONArray("courses_array");
    if (courseArray != null && courseArray.length() > 0) {
        JSONObject courceName;
        for (int j = 0; j < courseArray.length(); j++) {
            courceName = courseArray.optJSONObject(j);
            /*courceidchild.add(courceName.optString("cat_id"));*/
            courseName.add(courceName.optString("course_name_lan1"));
        }
        countries.add(new Country(strTitle, courseName));
    } else {
        countries.add(new Country(strTitle, courseName));
    }
    courseName.clear();
}

我的JSON

 {
      "data": {
        "data_list": [
          {
            "cat_id": "5",
            "cat_name_lan1": "Office Productivity",
            "cat_name_lan2": "ऑफिस प्रोडक्टिविटी",
            "cat_name_lan3": "ઓફિસ પ્રોડક્ટિવિટી",
            "cat_name_lan4": null,
            "cat_name_lan5": null,
            "cat_name_lan6": null,
            "courses_array": [
              {
                "course_id": "6",
                "course_name_lan1": "Google Docs Primary Level ",
                "course_name_lan2": "गुगल डॉक्स प्राथमिक स्तर",
                "course_name_lan3": "ગુગલ ડોક્સ પ્રાથમિક સ્તર",
                "course_name_lan4": "",
                "course_name_lan5": "",
                "course_name_lan6": "",
                "course_take": 1
              },
              {
                "course_id": "61",
                "course_name_lan1": "Financial Function Excel 2016",
                "course_name_lan2": "फाइनैन्शल फंक्शन एक्सेल 2016",
                "course_name_lan3": "ફાઇનૈન્શલ ફંક્શન એક્સેલ 2016",
                "course_name_lan4": "",
                "course_name_lan5": "",
                "course_name_lan6": "",
                "course_take": 0
              }
            ]
          },
          {
            "cat_id": "4",
            "cat_name_lan1": "I.T. & Software",
            "cat_name_lan2": "आईटी & सोफ्टवेयर",
            "cat_name_lan3": "આઈટી & સોફ્ટવેર",
            "cat_name_lan4": null,
            "cat_name_lan5": null,
            "cat_name_lan6": null,
            "courses_array": [
              {
                "course_id": "18",
                "course_name_lan1": "Google Forms",
                "course_name_lan2": "गुगल फॉर्म्स ",
                "course_name_lan3": "ગુગલ ફોર્મ્સ ",
                "course_name_lan4": "",
                "course_name_lan5": "",
                "course_name_lan6": "",
                "course_take": 0
              },
              {
                "course_id": "62",
                "course_name_lan1": "Google Drive",
                "course_name_lan2": "गुगल ड्राईव",
                "course_name_lan3": "ગુગલ ડ્રાઈવ ",
                "course_name_lan4": "",
                "course_name_lan5": "",
                "course_name_lan6": "",
                "course_take": 1
              }
            ]
          }
        ],
        "status": 0,
        "message": "Category and courses tree view."
      }
    }

courseName数组没有for循环，因此我在模型类中得到了空值

Answer 1

试试这个代码

// Initialize countries list
List<Country> countries = new ArrayList<>();

JSONObject jObj = new JSONObject(json);
JSONObject data = jObj.optJSONObject("data");
JSONArray datalist = data.optJSONArray("data_list");

// Iterate data_list JSONArray
for (int i = 0; i < datalist.length(); i++) {
    JSONObject jsonObject = datalist.getJSONObject(i);
    String strTitle = jsonObject.optString("cat_name_lan1");

    // Initialize courseName here
    ArrayList<String> courseName = new ArrayList<>();
    JSONArray courseArray = jsonObject.optJSONArray("courses_array");

    // Iterate courses_array JSONArray
    for (int j = 0; j < courseArray.length(); j++) {
        JSONObject courceName = courseArray.optJSONObject(j);
        courseName.add(courceName.optString("course_name_lan1"));
    }

    // Add strTitle and courseNames to countries list
    countries.add(new Country(strTitle, courseName));
}