java - how to handle entity manager can not find an object instance case? -


i have sceneario in have check if onject instance exist in entity manager. works fine when instance eexists throws null pointer exception when doesn't. when doesn't have thing. how can catch state? tried try catch, doesn't work.

sorry when asking question on way , trying type in different device used to. code is:

ajpacontroller ajpacontroller; aclass aclass = ajpacontroller.find((integer.parseint(request.getparameter("id")));  try{     if(ajpacontroller.contains(aclass)){        response.sendredirect("gosomewhere.com");      } } catch (java.lang.nullpointerexception r){      response.sendredirect("gosomewhereelse.com"); }

i might have logical mistake in trying first find , contains method, couldn't find better solution. in advance.

you can check if entity managed (within persistence context) of contains method of entitymanager


Comments

Post a Comment

Popular posts from this blog

c++ - Is it possible to compile a VST on linux? -

for class project i'm attempting write vst plugin backed cuda. current cuda workflow on linux box, i'd prefer compile , link there. according wikipedia , should possible (i couldn't find steinberg documentation relevant linux) can't find makefile or instructions on how build if aren't using xcode or visual studio. i'm vst 3 sdk doesn't support linux. when try compile plugin under linux, error: ./base/source/fatomic.cpp:39:30: fatal error: libkern/osatomic.h: no such file or directory this issue caused following code in "vst3 sdk/base/source/fatomic.cpp" #if mac #include <libkern/osatomic.h> #if mac_os_x_version_min_required > mac_os_x_version_10_4 #define native_atomic_type (volatile int32_t*) #else #define native_atomic_type (int32_t*) #endif #elif windows #include <windows.h> #endif but hope compiling under linux work vst sdk 2.4. reading. jvstwrapper seems run on lin...
Read more

java - Output of Eclipse is rubbish -

i want write program in eclipse language different english. when display output using system.out program, displays output correctly in console editor. when accept input console , output it, output rubbish. how can solve it. many thnaks i'm not sure if problem, have character encoding problem. make sure you're using unicode, utf-8. you can read more @ official docs converting non-unicode text .
Read more

jquery - Confused with JSON data and normal data in Django ajax request -

i read json internet still have not got grasp of it. reading article http://webcloud.se/log/ajax-in-django-with-jquery/ i not understood first part function using json def xhr_test(request, format): if request.is_ajax(): if format == 'xml': mimetype = 'application/xml' if format == 'json': mimetype = 'application/javascript' data = serializers.serialize(format, examplemodel.objects.all()) return httpresponse(data,mimetype) # if want prevent non xhr calls else: return httpresponse(status=400) my main problems are from function getting format variable does format json mean data given function json or data recived json can give me simple example ouput of function data = serializers.serialize(format, examplemodel.objects.all()) how use data when response in jquery function if don't use json in above function how input , response chnage thanks ...
Read more