我已经创建了IntentService类并执行了asyncTask但是当onPreExecute()在此代码行pDialog中被调用时出现异常。显示();AsyncHandlerService类---publicclassAsyncHandlerServiceextendsIntentService{ProgressDialogpDialog;HttpPostpost;HttpResponseresponse;Contextctx;publicAsyncHandlerService(){super("AsyncHandlerService");ctx=this;}@Overridepr