用 Java 解析 JSON 多维数组

Posted 2023-02-15

【中文标题】用 Java 解析 JSON 多维数组

【英文标题】：Parse JSON multidimensional array with Java

【发布时间】：2022-01-19 17:27:36

【问题描述】：

我是 Java 编码的新手，我想解析 json 响应，它看起来像这样：

    "13.12.2021  Monday": 
        "lessons": [
            
            "type": "second",
            "lesson":
                "subject": "ОР и АБД",
                "teacher": "Кузьмина В.М.",
                "room": null
                
            ,
            
                "type": "common",
                "0": 
                    "subject": "ПМ.2.Р5. РС и ПИР со С и ДК",
                    "teacher": "Голубева Я.С.",
                    "room": "211"
                
            
        ],
        "dinner": "11.00 "
        ,
    "14.12.2021  Tuesday": 
        "lessons":[
            
                "type": "common",
                "0":
                    "subject": "ПМ.2.Р1. ТРОПО",
                    "teacher": "Ахметова Ф.Т.","room":"212"
                
            ,
            
                "type": "common",
                "0":
                    "subject": "ПМ.2.Р1. ТРОПО",
                    "teacher": "Ахметова Ф.Т.",
                    "room": "212"
                
            
        ],
        "dinner": "11:00 "
    

我用这个代码

JSONObject json = new JSONObject(result);
Iterator<String> days = json.keys();

String response = "";

while(days.hasNext()) 
    String key = days.next();
    JSONObject day = json.getJSONObject(key);
    JSONArray lessons = day.getJSONArray("lessons");

    int lessonsCount = lessons.length(), i;
    for (i = 0; i < lessonsCount; i = i + 1) 
        JSONObject lesson = lessons.getJSONObject(i);
        response += lesson.getString("type") + '\n';
    


    response += '\n';

但是得到这个错误：

org.json.JSONException: Value [] at 4 of type org.json.JSONArray 无法转换为 JSONObject

请解释我如何访问所有子元素，例如“课程”块，它是“主题”、“老师”、“房间”。 我检查过类似的问题，但没有一个对我有帮助

【问题讨论】：

你在哪一行得到这个错误？

JSONObject lesson = lessons.getJSONObject(i);@Mike'Pomax'Kamermans

请记得说in your post。

【参考方案1】：

例如：

  StringBuilder response = new StringBuilder();
        while (days.hasNext()) 
            String key = days.next();
            JSONObject day = json.getJSONObject(key);
            JSONArray lessons = day.getJSONArray("lessons");
            for (int i = 0; i < lessons.length(); i++) 
                JSONObject lesson = lessons.getJSONObject(i);
                Iterator<String> item = lesson.keys();
                while (item.hasNext()) 
                    String jKey = item.next();
                    JSONObject jsonObject = lesson.optJSONObject(jKey);
                    if (jsonObject != null) 
                        parse(response, jsonObject);
                     else 
                        if (lesson.get(jKey) != null) 
                            response.append(lesson.getString(jKey)).append("\n");
                        
                    
                
            
            response.append('\n');
        


private void parse(StringBuilder response, JSONObject jsonObject) 
        if (jsonObject != null) 
            Iterator<String> item = jsonObject.keys();
            while (item.hasNext()) 
                String jKey = item.next();
                JSONObject jObject = jsonObject.optJSONObject(jKey);
                if (jObject != null) 
                    parse(response, jsonObject);
                 else 
                    response.append(jsonObject.get(jKey)).append("\n");
                
            
        
    

【参考方案2】：

我更新了您提供的功能以包含您的必填字段

     while(days.hasNext()) 
        String key = days.next();
        JSONObject day = json.getJSONObject(key);
        JSONArray lessons = day.getJSONArray("lessons");

        int lessonsCount = lessons.length(), i;
        for (i = 0; i < lessonsCount; i = i + 1) 
            JSONObject lesson = lessons.getJSONObject(i);
            Iterator<String> lessonKeys = lesson.keys();
            while(lessonKeys.hasNext()) 
                String lessonKey = lessonKeys.next();
                if(!lessonKey.equals("type")) 
                    JSONObject lessonData = lesson.getJSONObject(lessonKey);
                    response += lessonData.getString("subject")+" - "+lessonData.getString("teacher")+" - "+lessonData.get("room")+'\n';
                
            
        
    

输出如下：

ПМ.2.Р1. ТРОПО - Ахметова Ф.Т. - 212
ПМ.2.Р1. ТРОПО - Ахметова Ф.Т. - 212
ОР и АБД - Кузьмина В.М. - null
ПМ.2.Р5. РС и ПИР со С и ДК - Голубева Я.С. - 211