Java JsonObject JsonArray解析问题

我是JSON新手，但已经成功地从其他几个JSON请求中提取数据。这个给我带来了麻烦。任何帮助或指点都将不胜感激

这是JSON请求：

上面提到的数据是我想要的

以下是我遇到问题的代码：

public static ArrayList<CycloneData> extractFeatureFromJson(String cycloneJSON) {

    // Create an empty ArrayList to start adding Cyclones to
    ArrayList<CycloneData> cyclones = new ArrayList<>();

    // try to parse the cycloneJSON response string. If there's a problem with the way the JSON
    // is formatted, a JSONException exception object will be thrown.
    // Catch the exception, and print the error message to the logs.

    try {

        JSONObject rootJsonObject = new JSONObject(cycloneJSON);

        // Create JSONArray associated with the key called "currenthurricane", which represents
        // a list of cyclones from JSON response.
        JSONArray currentHurricaneArray = rootJsonObject.getJSONArray("currenthurricane");

        //Loop through each section in the currentHurricaneArray array & create an
        //{@link CycloneData} object for each one
        for (int i = 0; i < currentHurricaneArray.length(); i++) {
            //Get cyclone JSONObject at position i in the array
            JSONObject cycloneProperties = currentHurricaneArray.getJSONObject(i);
            //Extract “stormName_Nice” for Cyclone's name
            String name = cycloneProperties.optString("stormName_Nice");
            // Extract the value for the key called "url"
            String url = cycloneProperties.optString("url");
            int category = cycloneProperties.optInt("SaffirSimpsonCategory");
            CycloneData cyclone = new CycloneData(category, name, url);
            //Add new cyclone to list
            cyclones.add(cyclone);
        }

    } catch (JSONException e) {
        // If an error is thrown when executing any of the above statements in the "try" block,
        // catch the exception here, so the app doesn't crash. Print a log message
        // with the message from the exception.
        Log.e("Utils", "Problem parsing the cyclone JSON results", e);
    }

    // Return the list of cyclones
    return cyclones;
}

---

optString（字符串名称，字符串回退），返回按名称映射的值（如果存在），必要时强制该值，如果不存在此类映射，则返回回退。打印回退以进行测试。如果触发了回退，则没有键。这表明您的json结构格式不正确，或者您的解析逻辑不适合所使用的定义结构。

您在

stormName\u Nice

的解析过程中缺少json键

stormInfo

：

{
    "response": {
        "version": "0.1",
        "termsofService": "http://www.wunderground.com/weather/api/d/terms.html",
        "features": {
            "currenthurricane": 1
        }
    },
    "currenthurricane": [{
        "stormInfo": {
            "stormName": "Daniel",
            "stormName_Nice": "Hurricane Daniel",
            "stormNumber": "ep201204"
        },
        ...,
        "SaffirSimpsonCategory": 1,
        "url":"URL",
        ... 
    }]
}

它应该更好地处理以下问题：

JSONObject rootJsonObject = new JSONObject(cycloneJSON);

// Create JSONArray associated with the key called "currenthurricane", which represents
// a list of cyclones from JSON response.
JSONArray currentHurricaneArray = rootJsonObject.getJSONArray("currenthurricane");

//Loop through each section in the currentHurricaneArray array & create an
//{@link CycloneData} object for each one
for (int i = 0; i < currentHurricaneArray.length(); i++) {
    //Get cyclone JSONObject at position i in the array
    JSONObject cycloneProperties = currentHurricaneArray.getJSONObject(i);

    // Extract "stormInfo" object
    JSONObject stormInfo = cycloneProperties.getJSONObject("stormInfo");
    //Extract “stormName_Nice” for Cyclone's name
    String name = stormInfo.optString("stormName_Nice");

    // Extract other values from cycloneProperties
    String url = cycloneProperties.optString("url");
    int category = cycloneProperties.optInt("SaffirSimpsonCategory");
    CycloneData cyclone = new CycloneData(category, name, url);
    //Add new cyclone to list
    cyclones.add(cyclone);
}

JSONObject rootJsonObject=newjsonobject（cycloneJSON）；
//创建与名为“currenthurricane”的键关联的JSONArray，该键表示
//JSON响应中的气旋列表。
JSONArray currentHurricaneArray=rootJsonObject.getJSONArray（“currenthurricane”）；
//循环浏览currentHurricaneArray中的每个部分并创建一个
//每个对象的{@link CycloneData}对象
对于（int i=0；i

此时似乎“String name=cycloneProperties.optString（“stormName_Nice”）；”键不存在，因此它返回null。你确定这是正确的密钥吗？请添加你的JSONY添加你的json实际的一个。（显然）你提供给我们的json链接不起作用。是的，两个不同的结构，这就是了。让我走上正轨。我误解了我是如何拿到钥匙的。向原始帖子添加工作代码。

JSONObject rootJsonObject = new JSONObject(cycloneJSON);

// Create JSONArray associated with the key called "currenthurricane", which represents
// a list of cyclones from JSON response.
JSONArray currentHurricaneArray = rootJsonObject.getJSONArray("currenthurricane");

//Loop through each section in the currentHurricaneArray array & create an
//{@link CycloneData} object for each one
for (int i = 0; i < currentHurricaneArray.length(); i++) {
    //Get cyclone JSONObject at position i in the array
    JSONObject cycloneProperties = currentHurricaneArray.getJSONObject(i);

    // Extract "stormInfo" object
    JSONObject stormInfo = cycloneProperties.getJSONObject("stormInfo");
    //Extract “stormName_Nice” for Cyclone's name
    String name = stormInfo.optString("stormName_Nice");

    // Extract other values from cycloneProperties
    String url = cycloneProperties.optString("url");
    int category = cycloneProperties.optInt("SaffirSimpsonCategory");
    CycloneData cyclone = new CycloneData(category, name, url);
    //Add new cyclone to list
    cyclones.add(cyclone);
}