Question

请帮帮我，为什么我收到此错误。我正在使用convertStreamToString方法获取正确的字符串，将Json响应转换为字符串，我可以在我的logcat中看到此字符串。
现在我正在尝试将我的json响应字符串插入sqlite数据库，因为我正在使用

JSONObject HabitatObject = MyHabitatJsonObject.getJSONObject("HabitatDetails");    
JSONObject HabitatPosts = HabitatObject.getJSONObject("habitat");
    JSONArray HabitatPostsArray = HabitatPosts.getJSONArray("Post");
        ContentValues values = new ContentValues();
         DatabaseHelper InsertHabitat;     
        for (int i = 0; i < HabitatPostsArray.length(); i++) {
         values.put(InsertHabitat.PostUserImage, HabitatPostsArray.getJSONObject(i).getString("userimage").toString());
         values.put(InsertHabitat.PostUserName, HabitatPostsArray.getJSONObject(i).getString("username").toString());
    dbHabitat.insert(InsertHabitat.HABITATTABLE, null, values);
                }

直到现在一切都很好但是当我试图将这些值插入数据库时我在这一行上收到错误
values.put(InsertHabitat.PostUserImage, HabitatPostsArray.getJSONObject(i).getString("userpostimage").toString());

错误日志：

12-10 10:57:19.872: E/AndroidRuntime(301): FATAL EXCEPTION: AsyncTask #3
12-10 10:57:19.872: E/AndroidRuntime(301): java.lang.RuntimeException: An error occured while executing doInBackground()
12-10 10:57:19.872: E/AndroidRuntime(301):  at android.os.AsyncTask$3.done(AsyncTask.java:200)
12-10 10:57:19.872: E/AndroidRuntime(301):  at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
12-10 10:57:19.872: E/AndroidRuntime(301):  at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
12-10 10:57:19.872: E/AndroidRuntime(301):  at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
12-10 10:57:19.872: E/AndroidRuntime(301):  at java.util.concurrent.FutureTask.run(FutureTask.java:137)
12-10 10:57:19.872: E/AndroidRuntime(301):  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1068)
12-10 10:57:19.872: E/AndroidRuntime(301):  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:561)
12-10 10:57:19.872: E/AndroidRuntime(301):  at java.lang.Thread.run(Thread.java:1096)
12-10 10:57:19.872: E/AndroidRuntime(301): Caused by: java.lang.NullPointerException
12-10 10:57:19.872: E/AndroidRuntime(301):  at com.UserLogin.Habitat$HabitatResults.doInBackground(Habitat.java:90)
12-10 10:57:19.872: E/AndroidRuntime(301):  at com.UserLogin.Habitat$HabitatResults.doInBackground(Habitat.java:1)
12-10 10:57:19.872: E/AndroidRuntime(301):  at android.os.AsyncTask$2.call(AsyncTask.java:185)
12-10 10:57:19.872: E/AndroidRuntime(301):  at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
12-10 10:57:19.872: E/AndroidRuntime(301):  ... 4 more

Answer 1

我认为这是空的

HabitatPostsArray.getJSONObject(i).getString("userpostimage")

您是否尝试过打印该值？检查该行之前的值，基本检查如：

JSONObject jo = HabitatPostsArray.getJSONObject(i);

if (jo == null)
    Log.d("tag", "json obj null "+i);
if (!jo.has("userpostimage"))
    Log.d("tag", "key not present, you are not parsing correctly the json");

String s = jo.getString("userpostimage");
if (s == null)
    Log.d("tag", "userpostimage null");

Answer 2

尝试记录你的JsonObject [jo]，你在那里获得价值吗？ JSONObject jo = HabitatPostsArray.getJSONObject（i）;

if (jo == null)
    Log.d("tag", "json obj null "+i);
else 
    Log.d("tag", "json object at index" + i + " is : " + jo.toString());

asynctask中的空指针异常

2 个答案: