JSON problema de análisis no resuelto

Mis errores de LogCat son:

12-31 14:45:14.920: E/WindowManager(3420): Activity com.example.visit.record.My_Task has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@4054ed00 that was originally added here 12-31 14:45:14.920: E/WindowManager(3420): android.view.WindowLeaked: Activity com.example.visit.record.My_Task has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@4054ed00 that was originally added here 12-31 14:45:14.920: E/WindowManager(3420): at android.view.ViewRoot.<init>(ViewRoot.java:277) 12-31 14:45:14.920: E/WindowManager(3420): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:148) 12-31 14:45:14.920: E/WindowManager(3420): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:91) 12-31 14:45:14.920: E/WindowManager(3420): at android.view.Window$LocalWindowManager.addView(Window.java:433) 12-31 14:45:14.920: E/WindowManager(3420): at android.app.Dialog.show(Dialog.java:288) 12-31 14:45:14.920: E/WindowManager(3420): at com.example.visit.record.My_Task$GetTaskDetails.onPreExecute(My_Task.java:137) 12-31 14:45:14.920: E/WindowManager(3420): at android.os.AsyncTask.execute(AsyncTask.java:391) 12-31 14:45:14.920: E/WindowManager(3420): at com.example.visit.record.My_Task.onCreate(My_Task.java:105) 12-31 14:45:14.920: E/WindowManager(3420): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1093) 12-31 14:45:14.920: E/WindowManager(3420): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1785) 12-31 14:45:14.920: E/WindowManager(3420): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1842) 12-31 14:45:14.920: E/WindowManager(3420): at android.app.ActivityThread.access$1500(ActivityThread.java:132) 12-31 14:45:14.920: E/WindowManager(3420): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1038) 12-31 14:45:14.920: E/WindowManager(3420): at android.os.Handler.dispatchMessage(Handler.java:99) 12-31 14:45:14.920: E/WindowManager(3420): at android.os.Looper.loop(Looper.java:143) 12-31 14:45:14.920: E/WindowManager(3420): at android.app.ActivityThread.main(ActivityThread.java:4268) 12-31 14:45:14.920: E/WindowManager(3420): at java.lang.reflect.Method.invokeNative(Native Method) 12-31 14:45:14.920: E/WindowManager(3420): at java.lang.reflect.Method.invoke(Method.java:507) 12-31 14:45:14.920: E/WindowManager(3420): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 12-31 14:45:14.920: E/WindowManager(3420): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 12-31 14:45:14.920: E/WindowManager(3420): at dalvik.system.NativeStart.main(Native Method) 12-31 14:54:22.360: E/AndroidRuntime(4423): at com.example.visit.record.My_Task$GetTaskDetails.doInBackground(My_Task.java:163) 12-31 15:10:51.470: W/System.err(6457): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1088) 12-31 15:10:51.470: W/System.err(6457): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:581) 12-31 15:10:51.470: W/System.err(6457): at java.lang.Thread.run(Thread.java:1027) 12-31 15:10:51.480: E/Buffer Error(6457): Error converting result java.lang.NullPointerException 12-31 15:10:51.480: E/JSON Parser(6457): Error parsing data org.json.JSONException: End of input at character 0 of 12-31 15:10:51.480: W/dalvikvm(6457): threadid=9: thread exiting with uncaught exception (group=0x400205a0) 12-31 15:10:51.490: E/AndroidRuntime(6457): FATAL EXCEPTION: AsyncTask #1 12-31 15:10:51.490: E/AndroidRuntime(6457): java.lang.RuntimeException: An error occured while executing doInBackground() 12-31 15:10:51.490: E/AndroidRuntime(6457): at android.os.AsyncTask$3.done(AsyncTask.java:200) 12-31 15:10:51.490: E/AndroidRuntime(6457): at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:274) 12-31 15:10:51.490: E/AndroidRuntime(6457): at java.util.concurrent.FutureTask.setException(FutureTask.java:125) 12-31 15:10:51.490: E/AndroidRuntime(6457): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:308) 12-31 15:10:51.490: E/AndroidRuntime(6457): at java.util.concurrent.FutureTask.run(FutureTask.java:138) 12-31 15:10:51.490: E/AndroidRuntime(6457): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1088) 

Tengo error en dialog.show (); En el cuadro de diálogo Preexecute en la clase getTaskDetail. Y mostrar un error en Log.d ("Single Task Details", json.toString ()); Y obtuvo un error en el nuevo GetTaskDetails (). Execute ();

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Por favor, guíe por qué no obtener los valores de mi base de datos de aplicaciones php. Y se detuvo inesperadamente generando un error de "Fuerza Cerrar". Amablemente guía a dónde me equivoco. Quiero obtener datos de MySql a android usando JSONParsing

 private static final String url_read_mytask = "http://10.0.2.2/evisiting_records/read_mytask.php"; 

 private static final String url_update_mytask = "http://10.0.2.2/evisiting_records/update_mytask.php" 

 Error parsing data org.json.JSONException: End of input at character 0 of