尝试在 Android 中解析 JSON

Question

你建议我如何解析这个 JSON:

{"17": {"user_name": "test1"}, "18": {"user_name": "test5"}, "19": {"user_name": "test9"}}

我需要 "username"，但我找不到方法。也许我应该将 JSON 更改为类似的内容：

[{"user_name": "test1"},{"user_name": "test5"},{"user_name": "test9"}]

我试图通过这种方式获得 "user_name"s:

try {
        List<String> allNames = new ArrayList<String>();
        String str = "[{"user_name": "test1"},{"user_name": "test5"},{"user_name": "test9"}]";
        JSONObject json = new JSONObject(str);

            for ( int i = 0; i < json.length() ; i++)
            {
                JSONObject actor = json.getJSONObject(i);
                String user_name = actor.getString("user_name");
                allNames.add(user_name);
            }

} catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

但后来我遇到了那条线的问题：

JSONObject actor = json.getJSONObject(i);

Android studio 告诉我 JSONObject 不能应用于 int(i)。我不知道为什么它不起作用。

有人可以给我一些提示、教程或示例吗？

非常感谢！

Answer 1

Android studio tells me that JSONObject cannot be applied to int(i)

因为 JSONObject.getJSONObject 方法将键名作为 String 而不是 int。发布的 json 中的键是 17,18,... 以访问内部 JSONObject.

要从 JSONObject 获取所有 user_name，需要获取所有键：

Iterator<String> iter = json.keys();
while (iter.hasNext()) {
   String key = iter.next();
   JSONObject actor = json.getJSONObject(key);
   String user_name = actor.getString("user_name");
   allNames.add(user_name);
}

Answer 2

方法JSONObject.getJSONObject requires a String argument (the name or key of the object), not an int. In your case, the keys are "17", "18" and "19". To get all keys, use the JSONObject.keys()方法：

JSONObject json = new JSONObject(str);
Iterator<String> keyIterator = json.keys();
while (keyIterator.hasNext()) {
  JSONObject actor = json.getJSONObject(keyIterator.next());
  String user_name = actor.getString("user_name");
  allNames.add(user_name);
}

Answer 3

像这样更改您的代码

try {
    List<String> allNames = new ArrayList<String>();
    String str = "[{"user_name": "test1"},{"user_name": "test5"},{"user_name": "test9"}]";

    JSONOArray jsonArray = new JSONOArray(str);

        for ( int i = 0; i < jsonArray .length() ; i++)
        {
            JSONObject actor = jsonArray.getJSONObject(i);
            String user_name = actor.getString("user_name");
            allNames.add(user_name);
        }

} catch (JSONException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

Answer 4

str = {"17": {"user_name": "test1"}, "18": {"user_name": "test5"}, "19": {"user_name": "test9"}}
JSONObject ob1 = new JSONObject(str)
JSONObject ob2 = ob1.getJSONObject("17");
String userName = ob2.getString("user_name");


str = [{"user_name": "test1"},{"user_name": "test5"},{"user_name": "test9"}]
List<String> allNames = new ArrayList<String>();
JSONArray jsonArray = new JSONArray("str");
for(i=0; i < jsonArray.length(); i++){
    JSONObject ob = jsonArray.getJSONObject(i);
    allNames.add(ob.getString("user_name")
}

Answer 5

如果你使用 Gson 库就很简单了。

    String json = "{\"17\": {\"user_name\": \"test1\"}, \"18\": {\"user_name\": \"test5\"}, \"19\": {\"user_name\": \"test9\"}}";
    Gson gson = new GsonBuilder().create();
    Map<String,User> users = gson.fromJson(json, new TypeToken<Map<String,User> >(){}.getType());
    for(String key : users.keySet()) {
        Log.d("DEBUG",key+" -> "+users.get(key).getUser_name());
    }

用户 class 是一个简单的 POJO，例如：

public class 用户 {

private String user_name;

public String getUser_name() {
    return user_name;
}

public void setUser_name(String user_name) {
    this.user_name = user_name;
}

}

Answer 6

您正试图在

处将 JSONArray 解析为 JSONObject

JSONObject json = new JSONObject(str);

使用下面的代码......

try {
        List<String> allNames = new ArrayList<String>();
        String str = "[{"user_name": "test1"},{"user_name": "test5"},{"user_name": "test9"}]";
        JSONArray json = new JSONArray(str);

            for ( int i = 0; i < json.length() ; i++)
            {
                JSONObject actor = json.getJSONObject(i);
                String user_name = actor.getString("user_name");
                allNames.add(user_name);
            }

} catch (JSONException e) {
            // TODO Auto-generated catch block`enter code here`
            e.printStackTrace();
        }

尝试在 Android 中解析 JSON

Trying to parse JSON in Android

java

arrays

android

json

jsonobject