Dialog throwing Unable to add window token null is not for an application with getApplication as context

Question

My Activity is trying to create an AlertDialog which requires a Context as a parameter  This works as expected if I use   AlertDialog Builder builder   new AlertDialog Builder this     However  I am leery of using  this  as a context due to the potential for memory leaks when Activity is destroyed and recreated even during something simple like a screen rotation  From a related post on the Android developer s blog       There are two easy ways to avoid context-related memory leaks  The most obvious one is to avoid escaping the context outside of its own scope  The example above showed the case of a static reference but inner classes and their implicit reference to the outer class can be equally dangerous  The second solution is to use the Application context  This context will live as long as your application is alive and does not depend on the activities life cycle  If you plan on keeping long-lived objects that need a context  remember the application object  You can obtain it easily by calling Context getApplicationContext   or Activity getApplication      But for the AlertDialog   neither getApplicationContext   or getApplication   is acceptable as a Context  as it throws the exception        Unable to add window     token null is not for an application      per references  1  2  3  etc   So  should this really be considered a  bug   since we are officially advised to use Activity getApplication   and yet it doesn t function as advertised   Jim

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If you are outside of the Activity then you need to use in your function  NameOfMyActivity this  as Activity activity  example   public static void showDialog Activity activity            AlertDialog Builder builder   new AlertDialog Builder activity           builder setMessage  Your Message            setPositiveButton  Yes   dialogClickListener           setNegativeButton  No   dialogClickListener  show          Outside your Activity showDialog NameOfMyActivity this

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Instead of getApplicationContext    just use ActivityName this

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You ve correctly identified the problem when you said      for the AlertDialog   neither getApplicationContext   or getApplication   is acceptable as a Context  as it throws the exception   Unable to add window     token null is not for an application    To create a Dialog  you need an Activity Context or a Service Context  not an Application Context  both getApplicationContext   and getApplication   return an Application Context    Here s how you get the Activity Context    1  In an Activity or a Service   AlertDialog Builder builder   new AlertDialog Builder this     2  In a Fragment  AlertDialog Builder builder   new AlertDialog Builder getActivity      Memory leaks is not a problem that is intrinsic to the  this  reference  which is an object s reference to itself  i e  reference to the actual allocated memory for storing the object s data   It happens to any allocated memory for which the Garbage Collector  GC  is unable to free up after the allocated memory has outlived its useful lifespan   Most of the time  when a variable goes out of scope  the memory will be reclaimed by the GC  However  memory leaks can occur when the reference to an object held by a variable  say  x   persists even after the object has outlived its useful lifespan  The allocated memory will hence be lost for as long as  x  holds a reference to it because GC will not free up the memory for as long as that memory is still being referenced  Sometimes  memory leaks are not apparent because of a chain of references to the allocated memory  In such a case  the GC will not free up the memory until all references to that memory have been removed   To prevent memory leaks  check your code for logical errors that cause allocated memory to be referenced indefinitely by  this   or other references   Remember to check for chain references as well  Here are some tools you can use to help you analyze memory use and find those pesky memory leaks    JRockit Mission Control JProbe YourKit AD4J

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Use MyDialog md   new MyDialog MyActivity this getParent

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adding   dialog getWindow   setType WindowManager LayoutParams TYPE SYSTEM ALERT     and    android permission SYSTEM ALERT WINDOW   gt  in manifest  It works for me now  After even close and open the application  gave me the error at that time

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Try getParent   at the argument place of context like new AlertDialog Builder getParent     Hope it will work  it worked for me

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Here is how I resolved same error for my application  Adding the following line after creating the dialog     dialog getWindow   setType WindowManager LayoutParams TYPE SYSTEM DIALOG       You will not need to acquire a context  This is particularly useful if you are popping up another dialog over current popped up dialog  Or when it s not convenient to get a context     Hope this can help you with your app development     David

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Just use following   FOR JAVA USERS  In case you are using activity --   AlertDialog Builder builder   new AlertDialog Builder this    OR  AlertDialog Builder builder   new AlertDialog Builder your activity this    In case you are using fragment --   AlertDialog Builder builder   new AlertDialog Builder getActivity      FOR KOTLIN USERS  In case you are using activity --   val builder   AlertDialog Builder this   OR  val builder   AlertDialog Builder this your activity this   In case you are using fragment --   val builder   AlertDialog Builder activity

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kotlin version        You should pass this YourActivity instead of applicationContext or baseContext

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I was using ProgressDialog in a fragment and was getting this error on passing getActivity   getApplicationContext   as the constructor parameter  Changing it to getActivity   getBaseContext   didn t work either   The solution that worked for me was to pass getActivity    i e   progressDialog   new ProgressDialog getActivity

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If you are using a fragment and using AlertDialog Toast message then use getActivity   in the context parameter   like this  ProgressDialog pdialog  pdialog   new ProgressDialog getActivity     pdialog setCancelable true   pdialog setMessage  Loading         pdialog show

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Or another possibility is to create Dialog as follow   final Dialog dialog   new Dialog new ContextThemeWrapper              this  R style MyThemeDialog

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in Activity just use    MyActivity this   in Fragment   getActivity

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You can continue to use getApplicationContext    but before use  you should add this flag  dialog getWindow   setType WindowManager LayoutParams TYPE SYSTEM ALERT   and the error will not show   Add the following permission to your manifest    lt uses-permission android name  android permission SYSTEM ALERT WINDOW    gt

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I had to send my context through a constructor on a custom adapter displayed in a fragment and had this issue with getApplicationContext     I solved it with    this getActivity   getWindow   getContext   in the fragments  onCreate callback

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For future readers  this should help   public void show         if mContext instanceof Activity            Activity activity    Activity  mContext          if   activity isFinishing    amp  amp   activity isDestroyed                  dialog show

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I think it may happen as well if you are trying to show a dialog from a thread which is not the main UI thread   Use runOnUiThread   in that case

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Guys I got a simple cheat sheet  create a file give it any name then in it write this code  fun Context alertdialog context  Context  msg  String  icon  Drawable  title String       val alertDialog   AlertDialog Builder context      alertDialog setIcon icon           setTitle title           setMessage msg      alertDialog show       now when you need to show an alert dialog only use this method anywhere  requireActivity   alertdialog requireContext    resources getString R string pass title                   resources getDrawable R drawable pass ic name    title     Goodluck for Kotlin

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In Activity on click of button showing a dialog box     Dialog dialog   new Dialog MyActivity this     Worked for me

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After taking a look at the API  you can pass the dialog your activity or getActivity if you re in a fragment  then forcefully clean it up with dialog dismiss   in the return methods to prevent leaks   Though it is not explicitly stated anywhere I know  it seems you are passed back the dialog in the OnClickHandlers just to do this

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Using this did not work for me  but MyActivityName this did  Hope this helps anyone who could not get this to work

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If your Dialog is creating on the adapter   Pass the Activity to the Adapter Constructor   adapter   new MyAdapter getActivity   data     Receive on the Adapter    public MyAdapter Activity activity  List lt Data gt  dataList          this activity   activity          Now you can use on your Builder              AlertDialog Builder alert   new AlertDialog Builder activity

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What worked for me was to pass the activity instead of the context  I wanted a custom layout for my dialog  but to keep my code separate  I created it in a separate Class  else I would have to copy and paste that chunk of code into every activity where I want to use the dialog  Solution explains my situation but it gives the core solution   As I was using a ViewAdapter I initialised the adapter with the Activity  not context ex  - gt  kotlin  activity  Activity  as a parameter - gt  ex   kotlin  this MainActivity Then I passed that parameter to the Viewholder After which passing it again to the class that will inflate the Dialog   Use the activity optional name   Activity mandatory type  every where until it gets to the dialog you want to inflate Its a lot of passing around  but it does make more sense over copy and pasting the same code everywhere

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Try to use the context of an activity which will be under the dialog  But be carefull when you use  this  keyword  because it will not work everytime   Forexample  if you have TabActivity as host with two tabs  and each tab is another activity  and if you try to create dialog from one of the tabs  activities  and if you use  this   then you will get exception   In this case dialog should be connected to host activity which host everything and visible   you can say most visible parent Activity s context   I did not find this info from any document but by trying  This is my solution without strong background  If anybody with better knownledge  feel free to comment

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If you are using a fragment and using an AlertDialog   Toast message  use getActivity   in the context parameter   Worked for me   Cheers

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Your dialog should not be a  long-lived object that needs a context   The documentation is confusing  Basically if you do something like   static Dialog sDialog     note the static   Then in an activity somewhere you did   sDialog   new Dialog this     You would likely be leaking the original activity during a rotation or similar that would destroy the activity   Unless you clean up in onDestroy  but in that case you probably wouldn t make the Dialog object static   For some data structures it would make sense to make them static and based off the application s context  but generally not for UI related things  like dialogs  So something like this   Dialog mDialog        mDialog   new Dialog this     Is fine and shouldn t leak the activity as mDialog would be freed with the activity since it s not static

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In my case work   this getContext

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Little hack  you can prevent destroying your activity by GC  you should not do it  but it can help in some situations  Don t forget to set contextForDialog to null when it s no longer needed    public class PostActivity extends Activity                private Context contextForDialog   null              public void onCreate Bundle savedInstanceState                        contextForDialog   this                    private void showAnimatedDialog             mSpinner   new Dialog contextForDialog           mSpinner setContentView new MySpinner contextForDialog            mSpinner show

[android] Dialog throwing "Unable to add window — token null is not for an application” with getApplication() as context

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