Json 值 returns 在 Android 上解析时为空（如果不是）

Question

我试图在 Android 上读取这个 json 字符串，但是字段 "thumbnail" 总是 return 是空的，即使它实际上从来没有为空，它应该return url 或 "self"。

{
    "kind": "t3",
    "data": {
      "domain": "twitter.com",
      "banned_by": null,
      "media_embed": {},
      "subreddit": "nba",
      "id": "3y6vzw",
      "author": "Higgnkfe",
      "media": null,
      "score": 883,
      "approved_by": null,
      "over_18": false,
      "hidden": false,
      "num_comments": 811,
      "thumbnail": "http://b.thumbs.redditmedia.com/rfBhblr-DJIfsCEwQ9jq-wy_mHcmmedx3_Xy60STumc.jpg",
      "subreddit_id": "t5_2qo4s",
      "stickied": false,
      "from": null,
      "is_self": false,
      "from_id": null,
      "permalink": "/r/nba/comments/3y6vzw/first_all_star_results_are_in_kobe_steph_lead_the/",
      "created": 1451088664.0,
      "url": "https://twitter.com/nbaallstar/status/680417825463365632",
      "title": "First All Star Results are in; Kobe, Steph lead the vote",
      "created_utc": 1451059864.0,
      "ups": 883
    }

这是我用来阅读的一段代码：

        String title, author, subreddit, id, thumbnail = "test", url;
        int score, numOfComments;
        double created;
        boolean isSelf;

        JSONArray arr = new JSONObject(raw).getJSONObject("data").getJSONArray("children");

        for (int i = 0; i < arr.length(); i++) {
            JSONObject data = arr.getJSONObject(i).getJSONObject("data");

            Log.d("LOADER", "JSON: " + data.toString());

            title = data.getString("title");
            author = data.getString("author");
            subreddit = data.getString("subreddit");
            id = data.getString("id");
            thumbnail = data.getString("thumbnail");
            score = data.getInt("score");
            Log.d("LOADER", " thumb: " + thumbnail); // log shows "thumb:" only
            url = data.getString("url");
            created = data.getDouble("created");
            isSelf = data.getBoolean("is_self");
            numOfComments = data.getInt("num_comments");

            Post post = new Post(subreddit, title, author, url, id, score, numOfComments,
                     thumbnail, created, isSelf);

            posts.add(post);
        }

我阅读任何其他字段都没有问题，甚至 "url" 字段也包含 url，所以不可能是...

data.toString() 的日志显示如下：

JSON: {"domain":"self.nba","banned_by":null,.....(etc etc etc).......,"id":"3y46dt","num_comments":787,"thumbnail":"","subreddit_id":"t5_2qo4s","is_self":true,"from_id":null,"url":"https:\/\/www.reddit.com\/r\/nba\/comments\/3y46dt\/trash_talk_thread_no_games_today_because_of\/","author_flair_text":"[TOR] Luis Scola"....etc

如您所见，"thumbnail" 的值为“”，但 "url" 确实有一个 url。

这是怎么回事？

这是 url，我从中获取 json 字符串以防它有用 http://www.reddit.com/r/nba/.json

Answer 1

我自己查了一下，你的代码没有问题。事实上，您得到的 json 包含 empty 值 thumbnail。我去了你提供的 link 并且 starting 3 arrays contains empty value for thumbnail.所以你的代码是正确的，它与缩略图的值无关，无论它是 url 还是其他值。

Json 值 returns 在 Android 上解析时为空（如果不是）

Json value returns empty (when it's not) when parsing on Android

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