java lang IllegalStateException Fragment not attached to Activity

Question

I am rarely getting this error while making an API call   java lang IllegalStateException  Fragment  not attached to Activity   I tried putting the code inside isAdded   method to check whether  fragment is currently added to its activity but still i rarely gets this error  I fail to understand why I am still getting this error  How can i prevent it   Its showing error on the line-  cameraInfo setId getResources   getString R string camera id      Below is the sample api call that i am making        SAPI getInfo getActivity                    new APIResponseListener                          Override                     public void onResponse Object response                              cameraInfo   new SInfo                            if isAdded                                  cameraInfo setId getResources   getString R string camera id                                cameraInfo setName getResources   getString R string camera name                                cameraInfo setColor getResources   getString R string camera color                                cameraInfo setEnabled true                                                                           Override                     public void onError VolleyError error                            mProgressDialog setVisibility View GONE                           if  error instanceof NoConnectionError                                String errormsg   getResources   getString R string no internet error msg                               Toast makeText getActivity    errormsg  Toast LENGTH LONG  show

User · Answer

Fragment lifecycle is very complex and full of bugs  try to add    Activity activity   getActivity     if  isAdded    amp  amp  activity    null

User · Answer

Exception  java lang IllegalStateException  Fragment  DeadlineListFragment ad2ef970  not attached to Activity  Category  Lifecycle  Description  When doing time-consuming operation in background thread e g  AsyncTask   a new Fragment has been created in the meantime  and was detached to the Activity before the background thread finished  The code in UI thread e g  onPostExecute  calls upon a detached Fragment  throwing such exception   Fix solution    Cancel the background thread when pausing or stopping the Fragment Use isAdded   to check whether the fragment is attached and then to getResources   from activity

User · Answer

this happen when the fragment does not have a context  thus the getActivity  method return null   check if you use the context before you get it or if the Activity is not exist anymore   use context in fragment onCreate and after api response usually case this problem

User · Answer

This issue occurs whenever you call a context which is unavailable or null when you call it  This can be a situation when you are calling main activity thread s context on a background thread or background thread s context on main activity thread   For instance   I updated my shared preference string like following   editor putString  penname  penNameEditeText getText   toString     editor commit    finish      And called finish   right after it  Now what it does is that as commit runs on main thread and stops any other Async commits if coming until it finishes  So its context is alive until the write is completed  Hence previous context is live   causing the error to occur   So make sure to have your code rechecked if there is some code having this context issue

User · Answer

So the base idea is that you are running a UI operation on a fragment that is getting in the onDetach lifecycle  When this is happening the fragment is getting off the stack and losing the context of the Activity  So when you call UI related functions for example calling the progress spinner and you want to leave the fragment check if the Fragment is added to the stack  like this  if isAdded   progressBar visibility View VISIBLE

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This error happens due to the combined effect of two factors    The HTTP request  when complete  invokes either onResponse   or onError    which work on the main thread  without knowing whether the Activity is still in the foreground or not  If the Activity is gone  the user navigated elsewhere   getActivity   returns null  The Volley Response is expressed as an anonymous inner class  which implicitly holds a strong reference to the outer Activity class  This results in a classic memory leak    To solve this problem  you should always do   Activity activity   getActivity    if activity    null           etc          and also  use isAdded   in the onError   method as well    Override public void onError VolleyError error         Activity activity   getActivity         if activity    null  amp  amp  isAdded            mProgressDialog setVisibility View GONE           if  error instanceof NoConnectionError               String errormsg   getResources   getString R string no internet error msg              Toast makeText activity  errormsg  Toast LENGTH LONG  show

User · Answer

Sometimes this exception is caused by a bug in the support library implementation  Recently I had to downgrade from 26 1 0 to 25 4 0 to get rid of it

User · Answer

I Found Very Simple Solution  isAdded   method which is one of the fragment method to identify that this current fragment is attached to its Activity or not   we can use this like everywhere in fragment class like   if isAdded          using this method  we can do whatever we want which will prevent     java lang IllegalStateException  Fragment not attached to Activity   exception

User · Answer

I adopted the following approach for handling this issue  Created a new class which act as a wrapper for activity methods like this  public class ContextWrapper       public static String getString Activity activity  int resourceId  String defaultValue            if  activity    null                return activity getString resourceId             else               return defaultValue                         similar methods like getDrawable    getResources   etc      Now wherever I need to access resources from fragments or activities  instead of directly calling the method  I use this class  In case the activity context is not null it returns the value of the asset and in case the context is null  it passes a default value  which is also specified by the caller of the function    Important This is not a solution  this is an effective way where you can handle this crash gracefully  You would want to add some logs in cases where you are getting activity instance as null and try to fix that  if possible

User · Answer

This error can happen if you are instantiating a fragment that somehow can t be instantiated   Fragment myFragment   MyFragment NewInstance      public classs MyFragment extends Fragment     public void onCreate           Some error here  or anywhere inside the class is preventing it from being instantiated         In my case  i have met this when i tried to use   private String loading   getString R string loading

User · Answer

i may be late but may help someone        The best solution for this is to create a global application class instance and call it in the particular fragment where your activity is not being attached   as like below   icon   MyApplication getInstance   getString R string weather thunder     Here is application class  public class MyApplication extends Application        private static MyApplication mInstance      private RequestQueue mRequestQueue        Override     public void onCreate             super onCreate            mInstance   this             public static synchronized MyApplication getInstance             return mInstance

User · Answer

In Fragment use isAdded    It will return true if the fragment is currently attached to Activity   If you want to check inside the Activity   Fragment fragment   new MyFragment       if fragment getActivity    null             your code here        else           do something            Hope it will help someone

[android] java.lang.IllegalStateException: Fragment not attached to Activity

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