java 如何从文件解析 JSON 数组？
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How to parse JSON array from file?
提问by Nikolay Baranenko
I have JSON from file.
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"
}
]
}
and want to parse list of Solution and Num.
并想解析解决方案和数量的列表。
Used lib org.json.simple.*
使用 lib org.json.simple.*
Try this one
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());
}
What am I doing wrong?
我究竟做错了什么？
If try to write
如果尝试写
JSONObject solutions = (JSONArray) jsonObject.get("from_excel");
If try to write
如果尝试写
JSONArray array = obj.getJSONArray("from_excel");
get error
得到错误
回答by Nikolay Baranenko
working solution
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);
}
回答by Neeraj
There is no "solution" array in the JSON. "from_excel" is the array. So your code should look like this :
JSON 中没有“解决方案”数组。“from_excel”是数组。所以你的代码应该是这样的：
Object obj = parser.parse(new FileReader("E:\json.txt"));
JSONObject jsonObject = (JSONObject) obj;
out.println(jsonObject.get("from_excel"));
JSONArray solutions = (JSONArray) jsonObject.get("from_excel");
Iterator iterator = solutions.iterator();
while (iterator.hasNext()) {
out.println(iterator.next());
}
回答by SpringLearner
from_excel is JSON array not an object. So you should achieve it is array.
from_excel 是 JSON 数组而不是对象。所以你应该实现它是数组。
JSONObject jsonObject = (JSONObject) obj;
JSONArray array = obj.getJSONArray("from_excel");
then iterate the array and get each jsonobject. Something like the below
然后迭代数组并获取每个jsonobject。像下面这样的东西
for(int i = 0 ; i < array.length() ; i++){
array.getJSONObject(i).getString("solution");
}
