致命异常：AsyncTask＃1原因：java.lang.NullPointerException

Question

I'm getting a FATAL EXCEPTION with a NullPointerException in line 275 of mainActivity ( Log.d("Create Response", json.toString());) I have referenced the object before as JSONObject json = new JSONObject(); and I'm still getting null pointer. My log cat is below.

Log cat :

02-19 08:56:34.101: E/AndroidRuntime(1913): FATAL EXCEPTION: AsyncTask #1
02-19 08:56:34.101: E/AndroidRuntime(1913): Process: com.example.newjudoapp, PID: 1913
02-19 08:56:34.101: E/AndroidRuntime(1913): java.lang.RuntimeException: An error occured while executing doInBackground()
02-19 08:56:34.101: E/AndroidRuntime(1913):     at android.os.AsyncTask$3.done(AsyncTask.java:300)
02-19 08:56:34.101: E/AndroidRuntime(1913):     at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
02-19 08:56:34.101: E/AndroidRuntime(1913):     at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
02-19 08:56:34.101: E/AndroidRuntime(1913):     at java.util.concurrent.FutureTask.run(FutureTask.java:242)
02-19 08:56:34.101: E/AndroidRuntime(1913):     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
02-19 08:56:34.101: E/AndroidRuntime(1913):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
02-19 08:56:34.101: E/AndroidRuntime(1913):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
02-19 08:56:34.101: E/AndroidRuntime(1913):     at java.lang.Thread.run(Thread.java:841)
02-19 08:56:34.101: E/AndroidRuntime(1913): Caused by: java.lang.NullPointerException
02-19 08:56:34.101: E/AndroidRuntime(1913):     at com.example.newjudoapp.MainActivity$selectUser.doInBackground(MainActivity.java:275)
02-19 08:56:34.101: E/AndroidRuntime(1913):     at com.example.newjudoapp.MainActivity$selectUser.doInBackground(MainActivity.java:1)
02-19 08:56:34.101: E/AndroidRuntime(1913):     at android.os.AsyncTask$2.call(AsyncTask.java:288)
02-19 08:56:34.101: E/AndroidRuntime(1913):     at java.util.concurrent.FutureTask.run(FutureTask.java:237)
02-19 08:56:34.101: E/AndroidRuntime(1913):     ... 4 more

Answer 1

Whatever you are getting returned from...

json = jsonParser.hybridHTTPReuest(url, "POST", "GET", params);

...is null .

While you do instantiate a new instance, you then use it and set its value to null based on the return from the parser.

Answer 2

请检查返回“ hybridHTTPReuest（）”为空的内容

Answer 3

the json that u are passing to Log.d("Create Response", json.toString() ) method is null, and the method requires string to print, check your jsonParser.hybridHTTPReuest(url, "POST", "GET", params); method whether its returning any value or not , meanwhile u can use Log.d("Create Response", json.toString() +"")