致命异常：由：java.lang.NullPointerException引起的AsyncTask#1

Question

我在mainActivity（log.d（“create response”,json.toString（））的第275行得到一个带有NullPointerException的致命异常我以前引用了该对象为JSONObject json=new JSONObject（）；我仍然得到空指针。我的原木猫在下面。

日志猫：

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

u正在传递给log.d（“create response”,json.toString())方法的JSON为空，并且该方法需要打印字符串，检查您的jsonParser.HybridHttpReuest（url,“post”,“get”,params）；方法是否返回任何值，同时u可以使用log.d（“create response”,json.toString()+“”）