java.lang.IllegalStateException片段未附加到活动

Question

After I receive a response with Volley, I have to get back to the main fragment. I have two different volley requests , depending on some condition, I'll call it 'a' in this example. The weird thing is the when a==1, popBackStack gets me successfully to the main fragment . When a==0 it crashes and I receive java.lang.IllegalStateException Fragment not attached to Activity I tried creating a new main fragment (transaction.commit....) but it didn't help.

if( a == 0 )
{
    VolleyManager.add(jsnObj,
        new RequestListener() {

                    @Override
                    public <T> void onSuccess(T object) {
                        mFragmentManager.popBackStack(DataManager.BACK_STACK_KEY_MAIN_FRAGMENT, 0);
                    }
                    });
                }
else if( a==1 )
{
    VolleyManager.update(jsnObj,
        new RequestListener() {

                @Override
                public <T> void onSuccess(T object) {
                        mFragmentManager.popBackStack(DataManager.BACK_STACK_KEY_MAIN_FRAGMENT, 0);
                }   
                });
    }

Error -

  java.lang.IllegalStateException: Fragment MainFragment{6aaaf7f} not attached to Activity
  at android.app.Fragment.getResources(Fragment.java

The problem seems to be with the getResources() , but I do the same thing when a==1 and I've got no problems at all.

Answer 1

It seems like that by the time AsyncTask finishes and calls onPostExecute , the MainFragment has been detached from its activity . So either the activity has already been destroyed or fragment was never attached.

So if fragment is not attached to the activity , it can't access resources because that requires context and fragment doesn't have but activity does.

So you should check if activity is null or not before calling getResources .

Update the code like this:

if(getActivity()!=null){
    String streetFormat = getActivity().getResources().getString( R.string.address_name_string );
    ....
}

Answer 2

You have to cancel your requests on

onDestroyView()

method of the fragment or check if the fragment is already alive and added to host activity or not I'd go with something like this:

onDestroyView(){ Volley.cancelAllRequests() }

or

onResponse(){ if(getActivity() != null && isAdded(){ // here handle the response and update views, otherwise just cache the response!}}

Answer 3

getResources() must be called from something that has Context , like the activity. The fragment itself does not have the Context since it does not implement it. If you're using getResources() in a fragment, you can try this:

String streetFormat = getActivity().getResources().getString( R.string.address_name_string );