安卓JSONException对mediaGroup没有价值

Question

我正在尝试访问我的JSON结果的下一个级别。但是，它一直说mediaGroup元素没有值。我只设法在相同级别上处理其他元素，如title、contentSnippet和publishedDate。

这是json结果的一部分。

{
"responseData": {
    "feed": {
        "feedUrl": "http://www.abc.net.au/news/feed/51120/rss.xml",
        "title": "Just In",
        "link": "http://www.abc.net.au/news/justin/",
        "author": "",
        "description": "",
        "type": "rss20",
        "entries": [
            {
                "mediaGroups": [
                    {
                        "contents": [
                            {
                                "url": "http://www.abc.net.au/news/image/6951914-16x9-2150x1210.jpg",
                                "type": "image/jpeg",
                                "medium": "image",
                                "height": 1210,
                                "width": 2150,
                                "lang": "en-US",
                                "description": "The stockpile at Longford contains more than a million tyres. (ABC News: Damian McIntyre)",
                                "thumbnails": [
                                    {
                                        "height": 105,
                                        "width": 140,
                                        "url": "http://www.abc.net.au/news/image/6951914-4x3-140x105.jpg"
                                    }
                                ]
                            },
                            {
                                "url": "http://www.abc.net.au/news/image/6951914-4x3-940x705.jpg",
                                "type": "image/jpeg",
                                "medium": "image",
                                "height": 705,
                                "width": 940,
                                "lang": "en-US",
                                "description": "The stockpile at Longford contains more than a million tyres. (ABC News: Damian McIntyre)",
                                "thumbnails": [
                                    {
                                        "height": 105,
                                        "width": 140,
                                        "url": "http://www.abc.net.au/news/image/6951914-4x3-140x105.jpg"
                                    }
                                ]
                            },
                            {
                                "url": "http://www.abc.net.au/news/image/6951914-3x2-940x627.jpg",
                                "type": "image/jpeg",
                                "medium": "image",
                                "isDefault": "true",
                                "height": 627,
                                "width": 940,
                                "lang": "en-US",
                                "description": "The stockpile at Longford contains more than a million tyres. (ABC News: Damian McIntyre)",
                                "thumbnails": [
                                    {
                                        "height": 105,
                                        "width": 140,
                                        "url": "http://www.abc.net.au/news/image/6951914-4x3-140x105.jpg"
                                    }
                                ]
                            },
                            {
                                "url": "http://www.abc.net.au/news/image/6951914-3x4-940x1253.jpg",
                                "type": "image/jpeg",
                                "medium": "image",
                                "height": 1253,
                                "width": 940,
                                "lang": "en-US",
                                "description": "The stockpile at Longford contains more than a million tyres. (ABC News: Damian McIntyre)",
                                "thumbnails": [
                                    {
                                        "height": 105,
                                        "width": 140,
                                        "url": "http://www.abc.net.au/news/image/6951914-4x3-140x105.jpg"
                                    }
                                ]
                            },
                            {
                                "url": "http://www.abc.net.au/news/image/6951914-1x1-1400x1400.jpg",
                                "type": "image/jpeg",
                                "medium": "image",
                                "height": 1400,
                                "width": 1400,
                                "lang": "en-US",
                                "description": "The stockpile at Longford contains more than a million tyres. (ABC News: Damian McIntyre)",
                                "thumbnails": [
                                    {
                                        "height": 105,
                                        "width": 140,
                                        "url": "http://www.abc.net.au/news/image/6951914-4x3-140x105.jpg"
                                    }
                                ]
                            }
                        ]
                    }
                ],
                "title": "New proposed tyre shredding facility receives EPA approval",
                "link": "http://www.abc.net.au/news/2016-05-28/tyre-shredding-facility-proposed-tasmania-south-epa-approval/7456326",
                "author": "",
                "publishedDate": "Fri, 27 May 2016 23:42:46 -0700",
                "contentSnippet": "A long-term solution to Tasmania's tyre waste problem is on the horizon, with a new facility preparing to shred thousands of ...",
                "content": "<p>A long-term solution to Tasmania's tyre waste problem is on the horizon, with a new facility preparing to shred thousands of tyres every year.</p>",
                "categories": [
                    "Environmental Impact",
                    "Environment",
                    "Government and Politics"
                ]

这是我的代码来解析它

public List<NewsObj> constructJSON(String jsonIN){
    ArrayList<NewsObj> newsList = new ArrayList<>();
    try{
        //add more levels to extract json
        JSONObject jsonObject1 = new JSONObject(jsonIN);
        String responseData = jsonObject1.getString("responseData");
        Log.d("RECEIVEJSONOBJECTLEVEL1",responseData);

        JSONObject jsonObject2 = new JSONObject(responseData);
        String feed = jsonObject2.getString("feed");
        Log.d("RECEIVEJSONOBJECTLEVEL2",feed);

        JSONObject jsonObject3 = new JSONObject(feed);
        String entries = jsonObject3.getString("entries");
        Log.d("RECEIVEJSONOBJECTLEVEL3",entries); //this opens up further thumbnail sizes



        JSONArray jsonArray1 = new JSONArray(entries);
        for(int i=0; i<jsonArray1.length();i++){
            JSONObject mediaGroups = jsonArray1.getJSONObject(i);
            JSONArray jsonArray2 = mediaGroups.getJSONArray("mediaGroups");
            String title = mediaGroups.getString("title");
            String url = mediaGroups.getString("link");
            String description = mediaGroups.getString("contentSnippet");
            String publishedDate = mediaGroups.getString("publishedDate");
//                main information for news article
            Log.d("RECEIVEJSONOBJECTLEVEL4",title);
            Log.d("RECEIVEJSONOBJECTLEVEL4",url);
            Log.d("RECEIVEJSONOBJECTLEVEL4",description);
            Log.d("RECEIVEJSONOBJECTLEVEL4",publishedDate);
            NewsObj aObj = new NewsObj(title,url,publishedDate);
            newsList.add(aObj);

我似乎无法从mediaGroup中找到任何价值。请帮帮忙

Answer 1

若要访问内容数组，请执行以下操作：

JSONArray contents = jsonArray1.getJSONObject(i).getJSONArray("mediaGroups").getJSONObject(0).getJSONArray("contents");

然后：

String url = contents.getJSONObject(i).getString("url");

若要访问缩略图数组，请执行以下操作：

JSONArray thumbnails = contents.getJSONObject(i).getJSONArray("thumbnails");
String thumbNailURL = thumbnails.getJSONObject(0).getString("url");

Answer 2

mediaGroup是JsonArray而不是JsonObject。要访问它，请执行如下操作

JSONObject jsonObj= jsonArray1.getJSONObject(i);
JSONArray media=jsonObj.getJSONArray("mediaGroups");

你的下一个问题是

String entries = jsonObject3.getString("entries");

条目也是一个json，所以您也必须得到它

JSONArray entries=jsonObject3.getJSONArray("entries");