java - 如何从文件中解析 JSON 数组？

Question

我有来自文件的 JSON。

{  
  "from_excel":[  
    {  
      "solution":"Fisrt",
      "num":"1"
    },
    {  
      "solution":"Second",
      "num":"2"
    },
    {  
      "solution":"third",
      "num":"3"
    },
    {  
      "solution":"fourth",
      "num":"4"
    },
    {  
      "solution":"fifth",
      "num":"5"
    }
  ]
}

并且想要解析解决方案和 Num 的列表。

使用liborg.json.simple.*

试试这个

        Object obj = parser.parse(new FileReader("E:\\json.txt"));        JSONObject jsonObject = (JSONObject) obj;        out.println(jsonObject.get("from_excel"));        JSONObject obj_new = (JSONObject) jsonObject.get("from_excel");        JSONArray solution = (JSONArray) obj_new.get("solution");        Iterator iterator = solution.iterator();        while (iterator.hasNext()) {            out.println(iterator.next());        }

我做错了什么？

如果尝试写

JSONObject solutions = (JSONArray) jsonObject.get("from_excel");

如果尝试写

JSONArray array = obj.getJSONArray("from_excel");

出现错误

Answer 1

工作解决方案

JSONParser parser = new JSONParser();
JSONObject jsonObject;
try {

    jsonObject = (JSONObject) parser.parse(new FileReader("E:\\json.txt"));

    out.println("<br>"+jsonObject);


    JSONArray from_excel = (JSONArray)jsonObject.get("from_excel");
    // for row output 1
    for(Object o: from_excel){
        out.println("<br>"+o);
    }
    // for row output 2
    Iterator iterator = from_excel.iterator();
    while (iterator.hasNext()) {
        out.println("<br>"+iterator.next());
    }
    // for item output 3
    for (int i = 0; i < from_excel.size(); i++) {

        JSONObject jsonObjectRow = (JSONObject) from_excel.get(i);
        String num = (String) jsonObjectRow.get("num");
        String solution = (String) jsonObjectRow.get("solution");
        out.println("<br>num="+num+"; solution="+solution);
    }
} catch (Exception e) {
    out.println("Error: "+e);
}