Java - 未找到 JSONObject

Question

我正在尝试从 API 收集单个数据，即某个国家/地区的人口。除了从 JSON 中删除人口值之外，一切正常。

{"Info":[{"area":301336,"nativeName":"Italia","capital":"Rome","demonym":"Italian","flag":"https://restcountries.eu/data/ita.svg","alpha2Code":"IT","languages":[{"nativeName":"Italiano","iso639_2":"ita","name":"Italian","iso639_1":"it"}],"borders":["AUT","FRA","SMR","SVN","CHE","VAT"],"subregion":"Southern Europe","callingCodes":["39"],"regionalBlocs":[{"otherNames":[],"acronym":"EU","name":"European Union","otherAcronyms":[]}],"gini":36,"population":60665551,"numericCode":"380","alpha3Code":"ITA","topLevelDomain":[".it"],"timezones":["UTC+01:00"],"cioc":"ITA","translations":{"br":"Itália","de":"Italien","pt":"Itália","ja":"イタリア","hr":"Italija","it":"Italia","fa":"ایتالیا","fr":"Italie","es":"Italia","nl":"Italië"},"name":"Italy","altSpellings":["IT","Italian Republic","Repubblica italiana"],"region":"Europe","latlng":[42.83333333,12.83333333],"currencies":[{"symbol":"\u20ac","code":"EUR","name":"Euro"}]}]}

在 JSON 中，它被称为“Population”。

这是我的用户输入代码

public static String UserInputsDetails() {
    System.out.println("Please input the country name");
    Scanner in = new Scanner(System.in);
    String Input = in.nextLine();
    return Input;
}

这是我的 JSON Getter 代码

    public static JSONArray MakeConnection(String countryname) {
    JSONArray JSON = null;
    try {

        String url = "https://restcountries.eu/rest/v2/name/" + countryname;

        URL obj = new URL(url);
        HttpURLConnection con = (HttpURLConnection) obj.openConnection();

        int responseCode = con.getResponseCode();
        System.out.println("\nSending 'GET' request to URL : " + url);
        System.out.println("Response Code : " + responseCode);
        BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
        String inputLine;
        StringBuffer response = new StringBuffer();

        while((inputLine = in.readLine()) != null) {
            response.append(inputLine);
        }
        in.close();

        JSON = new JSONArray(response.toString());

    } catch (Exception e) {
        System.out.println(e);
    }
    return JSON;
}

这是我的结果代码，用于获取人口

    public static void PrintResult(JSONArray JSON){
    String population = null;
try {
    JSONObject jobj = new JSONObject();
    jobj.put("Info", JSON);

    population = jobj.getString("population");
    System.out.println(jobj);

    System.out.println(population);

    } catch (Exception e) {
    System.out.println(e);
    }

}

最后，这是我的主要内容

public static void main(String []args) {
    String Input =  UserInput.UserInputsDetails();
    JSONArray JSON = Connection.MakeConnection(Input);
    Result.PrintResult(JSON);
}

我收到错误

org.json.JSONException: JSONObject["population"] not found.

我做错了什么？

Answer 1

删除这部分:

JSONObject jobj = new JSONObject();
jobj.put("Info", JSON);

population = jobj.getString("population");
System.out.println(jobj);

System.out.println(population);

JSON 已经是一个数组了，为什么要把它转换成 JSONObject？

更改为这样的内容:

Long population = JSON.getJSONObject(0).getLong("population");