java - 如何从 JSONObject 检索 Id

Question

我在从 JSONObject 检索 Id 并将其传递给 String 来记录该玩家特定谜题的 Id 时遇到问题，但在 String idString = obj.getString("Id"); 行上

“我收到 org.json.JSONException:Id 没有值”

我通过调用此类中的服务器来获取此信息，该服务器检查玩家的用户名和密码。

import android.os.AsyncTask;
import android.text.format.Time;
import android.util.Log;

public class GetTodaysPuzzle implements OnRetrieveHttpData {

    public String GetTodaysPuzzle(String mUserName, String mPassword)
    {
        RetrieveHTTPData GetTodayspuzzle = new RetrieveHTTPData(this);
        return GetTodayspuzzle.GetResponseData("urlString" + mUserName + "&password=" + mPassword);
    }

    @Override
    public void onRetrieveTaskCompleted(String httpData) {
        Log.i("Server Response", httpData);
    }

    class GetTodaysPuzzleTask extends AsyncTask<String, String, Boolean> {

        @Override
        protected Boolean doInBackground(String... params) {
            // Get response from server
            String json = GetTodaysPuzzle(params[0], params[1]);

            // Check if a puzzle was returned
            if (json.contains("The request is invalid"))
            {
                return false;
            }

            try
            {
                // Calculate today's date in order to set wordsearch date
                Time today = new Time();
                today.setToNow();
                String formattedDate = Dates.ConvertUStoUK(today.year + "-"
                        + (today.month + 1) + "-" + today.monthDay);

                // Create wordsearch
                WordSearch wordSearch = WordSearch.CreateWordSearch(json,
                        formattedDate);

                if (wordSearch == null)
                {
                    return false;
                }

                // Save wordsearch to collection
                WordSearchDatabase.Add(wordSearch);
                // WordSearchDatabase.Save();
                return true;
            }
            catch (Exception e)
            {
                Log.e("GetTodaysPuzzleTask", e.getMessage());
                return false;
            }
        }
    }

}

然后将所有信息存储到 Wordsearch 类中的 JSONArrays 中。

import java.util.ArrayList;
import java.util.List;
import org.json.JSONArray;
import org.json.JSONObject;

public class WordSearch {

    public String               Id;
    public String               Date;
    public List<Word>           Words;
    public Letter[]             Letters;
    public final int            NUM_OF_ROWS;
    public final int            NUM_OF_COLS;
    public int                  Score               = -1;

    private boolean             containsSolution    = false;
    public boolean              canBeSubmitted      = true;
    private boolean             complete            = false;
    private boolean             submitted           = false;


    public static WordSearch CreateWordSearch(String json, String date)
    {
        List<Word> listOfWords = new ArrayList<Word>();
        List<String> listOfRows = new ArrayList<String>();

        try
        {
            // Create a JSON Object from JSON string
            JSONObject obj = new JSONObject(json);

            // Get Id
            String idString = obj.getString("Id");

            // GetWords & Puzzle as JSON Arrays
            JSONArray wordsArray = obj.getJSONArray("Words");
            JSONArray puzzleArray = obj.getJSONArray("Grid");

            // Parse Words array
            for (int i = 0; i < wordsArray.length(); i++)
            {
                String name = wordsArray.getString(i);
                Word word = new Word(name);
                listOfWords.add(word);
            }

            // Parse Puzzle
            for (int k = 0; k < puzzleArray.length(); k++)
            {
                String puzzle = puzzleArray.getString(k);
                listOfRows.add(puzzle);
            }

            // Create WordSearch
            return new WordSearch(idString, date, listOfWords, listOfRows,
                    false);
        }
        catch (Exception e)
        {
            e.printStackTrace();
            return null;
        }
    }
}

这是我第一次在 Android 中使用 API 服务器和 JSONObject，因此我们将不胜感激。谢谢。

Answer 1

您收到此错误是因为您的响应 JSON 没有“Id”作为键，它只有“Puzzle”，如您所见:

{
   "Puzzle": {
       "Id": "8fb25209-863a-410b-a440-b5b57a903ee1",
       "Words": ["CHATEAUX", ...],
       "Grid": ["TLIOFSHTRC", ...]
   }
}

您需要先获取“Puzzle”对象，然后才能从该对象中获取“Id”。

JSONObject obj = new JSONObject(json);
JSONObject puzzle = obj.getJSONObject("Puzzle");
String idString = puzzle.getString("Id");
....