我的用户报告说,当他们使用 WiFi 下载 JSON 文件时,该应用程序就像魅力一样工作,但是当他们尝试使用他们的数据连接下载相同的文件时:GPRS、3G、3.5G 等......应用程序强制关闭。并非所有类型的智能手机都会发生这种情况,例如,我的 LG Optimus Black 不会发生这种情况。
为了检索这个文件,我使用了 AsyncTask。
private class GetData extends AsyncTask<Void, Void, Void> {
protected Void doInBackground(Void... args) {
DefaultHttpClient httpclient = new DefaultHttpClient();
try {
HttpGet httpget = new HttpGet("http://url.com);
HttpResponse response = httpclient.execute(httpget);
strPlayers = inputStreamToString(response.getEntity().getContent()).toString();
}
catch (IOException e) { e.printStackTrace(); }
finally { httpclient.getConnectionManager().shutdown(); }
return null;
}
protected void onPostExecute(Void result) {
Players players = new Gson().fromJson(strPlayers, Players.class);
quantity_darkmatter.setText(String.valueOf(players.userName));
}
}
这是 StackTrace()
java.lang.RuntimeException: Unable to start activity ComponentInfo{carl.fri.fer.omegan/carl.fri.fer.omegan.Research}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1659)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1675)
at android.app.ActivityThread.access$1500(ActivityThread.java:121)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:943)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:130)
at android.app.ActivityThread.main(ActivityThread.java:3701)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:507)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:624)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at carl.fri.fer.omegan.Research.onStart(Research.java:613)
at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1129)
at android.app.Activity.performStart(Activity.java:3791)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1632)
... 11 more
可能是什么问题?