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"android.view.WindowManager$BadTokenException: Unable to add window" on buider.show()

Posted by: admin March 11, 2020 Leave a comment

Questions:

From my main activity, I need to call an inner class and in a method within the class, I need to show AlertDialog. After dismissing it, when the OK button is pressed, forward to Google Play for purchase.

Things work perfectly for most of the times, but for few users it is crashing on builder.show() and I can see "android.view.WindowManager$BadTokenException: Unable to add window” from crash log. Please suggest.

My code is pretty much like this:

public class classname1 extends Activity{

  public void onCreate(Bundle savedInstanceState) {
    this.requestWindowFeature(Window.FEATURE_NO_TITLE);
    super.onCreate(savedInstanceState);
    setContentView(R.layout.<view>); 

    //call the <className1> class to execute
  }

  private class classNamename2 extends AsyncTask<String, Void, String>{

    protected String doInBackground(String... params) {}

    protected void onPostExecute(String result){
      if(page.contains("error")) 
      {
        AlertDialog.Builder builder = new AlertDialog.Builder(classname1.this);
        builder.setCancelable(true);
        builder.setMessage("");
        builder.setInverseBackgroundForced(true);
        builder.setNeutralButton("Ok",new DialogInterface.OnClickListener() {
          public void onClick(DialogInterface dialog, int whichButton){
            dialog.dismiss();
            if(!<condition>)
            {
              try
              {
                String pl = ""; 

                mHelper.<flow>(<class>.this, SKU, RC_REQUEST, 
                  <listener>, pl);
              }

              catch(Exception e)
              {
                e.printStackTrace();
              }
            }  
          }
        });

        builder.show();
      }
    }
  }
}

I have also seen the error in another alert where I am not forwarding to any other activity. It’s simple like this:

AlertDialog.Builder builder = new AlertDialog.Builder(classname1.this);
    builder.setCancelable(true);

    //if successful
    builder.setMessage(" ");
    builder.setInverseBackgroundForced(true);
    builder.setNeutralButton("Ok",new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int whichButton){
            // dialog.dismiss();
                   }
    });
    builder.show();
}
How to&Answers:
android.view.WindowManager$BadTokenException: Unable to add window"

Problem :

This exception occurs when the app is trying to notify the user from
the background thread (AsyncTask) by opening a Dialog.

If you are trying to modify the UI from background thread (usually
from onPostExecute() of AsyncTask) and if the activity enters
finishing stage i.e.) explicitly calling finish(), user pressing home
or back button or activity clean up made by Android then you get this
error.

Reason :

The reason for this exception is that, as the exception message says,
the activity has finished but you are trying to display a dialog with
a context of the finished activity. Since there is no window for the
dialog to display the android runtime throws this exception.

Solution:

Use isFinishing() method which is called by Android to check whether
this activity is in the process of finishing: be it explicit finish()
call or activity clean up made by Android. By using this method it is
very easy to avoid opening dialog from background thread when activity
is finishing.

Also maintain a weak reference for the activity (and not a strong
reference so that activity can be destroyed once not needed) and check
if the activity is not finishing before performing any UI using this
activity reference (i.e. showing a dialog).

eg.

private class chkSubscription extends AsyncTask<String, Void, String>{

  private final WeakReference<login> loginActivityWeakRef;

  public chkSubscription (login loginActivity) {
    super();
    this.loginActivityWeakRef= new WeakReference<login >(loginActivity)
  }

  protected String doInBackground(String... params) {
    //web service call
  }

  protected void onPostExecute(String result) {
    if(page.contains("error")) //when not subscribed
    {
      if (loginActivityWeakRef.get() != null && !loginActivityWeakRef.get().isFinishing()) {
        AlertDialog.Builder builder = new AlertDialog.Builder(login.this);
        builder.setCancelable(true);
        builder.setMessage(sucObject);
        builder.setInverseBackgroundForced(true);

        builder.setNeutralButton("Ok",new DialogInterface.OnClickListener() {
          public void onClick(DialogInterface dialog, int whichButton){
            dialog.dismiss();
          }
        });

        builder.show();
      }
    }
  }
}

Update :

Window Tokens:

As its name implies, a window token is a special type of Binder token
that the window manager uses to uniquely identify a window in the
system. Window tokens are important for security because they make it
impossible for malicious applications to draw on top of the windows of
other applications. The window manager protects against this by
requiring applications to pass their application’s window token as
part of each request to add or remove a window. If the tokens don’t
match, the window manager rejects the request and throws a
BadTokenException. Without window tokens, this necessary
identification step wouldn’t be possible and the window manager
wouldn’t be able to protect itself from malicious applications.

 A real-world scenario:

When an application starts up for the first time,
the ActivityManagerService creates a special kind of window token
called an application window token, which uniquely identifies the
application’s top-level container window. The activity manager gives
this token to both the application and the window manager, and the
application sends the token to the window manager each time it wants
to add a new window to the screen. This ensures secure interaction
between the application and the window manager (by making it
impossible to add windows on top of other applications), and also
makes it easy for the activity manager to make direct requests to the
window manager.

Answer:

I had dialog showing function:

void showDialog(){
    new AlertDialog.Builder(MyActivity.this)
    ...
    .show();
}

I was getting this error and i just had to check isFinishing() before calling this dialog showing function.

if(!isFinishing())
    showDialog();

Answer:

The possible reason is the context of the alert dialog. You may be finished that activity so its trying to open in that context but which is already closed.
Try changing the context of that dialog to you first activity beacause it won’t be finished till the end.

e.g

rather than this.

AlertDialog alertDialog = new AlertDialog.Builder(this).create();

try to use

AlertDialog alertDialog = new AlertDialog.Builder(FirstActivity.getInstance()).create();

Answer:

  • first you cannot extend AsyncTask without override doInBackground
  • second try to create AlterDailog from the builder then call show().

    private boolean visible = false;
    class chkSubscription extends AsyncTask<String, Void, String>
    {
    
        protected void onPostExecute(String result)
        {
            AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
            builder.setCancelable(true);
            builder.setMessage(sucObject);
            builder.setInverseBackgroundForced(true);
            builder.setNeutralButton("Ok", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int whichButton)
                {
                    dialog.dismiss();
                }
            });
    
            AlertDialog myAlertDialog = builder.create();
            if(visible) myAlertDialog.show();
        }
    
        @Override
        protected String doInBackground(String... arg0)
        {
            // TODO Auto-generated method stub
            return null;
        }
    }
    
    
    @Override
    protected void onResume()
    {
        // TODO Auto-generated method stub
        super.onResume();
        visible = true;
    }
    
    @Override
    protected void onStop()
    {
        visible = false; 
        super.onStop();
    }
    

Answer:

I am creating Dialog in onCreate and using it with show and hide. For me the root cause was not dismissing onBackPressed, which was finishing the Home activity.

@Override
public void onBackPressed() {
new AlertDialog.Builder(this)
                .setTitle("Really Exit?")
                .setMessage("Are you sure you want to exit?")
                .setNegativeButton(android.R.string.no, null)
                .setPositiveButton(android.R.string.yes,
                        new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog,
                                    int which) {
                                Home.this.finish();
                                return;
                            }
                        }).create().show();

I was finishing the Home Activity onBackPressed without closing / dismissing my dialogs.

When I dismissed my dialogs the crash disappeared.

new AlertDialog.Builder(this)
                .setTitle("Really Exit?")
                .setMessage("Are you sure you want to exit?")
                .setNegativeButton(android.R.string.no, null)
                .setPositiveButton(android.R.string.yes,
                        new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog,
                                    int which) {
                                networkErrorDialog.dismiss() ;
                                homeLocationErrorDialog.dismiss() ;
                                currentLocationErrorDialog.dismiss() ;
                                Home.this.finish();
                                return;
                            }
                        }).create().show();

Answer:

I try this it solved.

 AlertDialog.Builder builder = new AlertDialog.Builder(
                   this);
            builder.setCancelable(true);
            builder.setTitle("Opss!!");

            builder.setMessage("You Don't have anough coins to withdraw. ");
            builder.setMessage("Please read the Withdraw rules.");
            builder.setInverseBackgroundForced(true);
            builder.setPositiveButton("OK",
                    (dialog, which) -> dialog.dismiss());
            builder.create().show();

Answer:

Try this :

    public class <class> extends Activity{

    private AlertDialog.Builder builder;

    public void onCreate(Bundle savedInstanceState) {
                    this.requestWindowFeature(Window.FEATURE_NO_TITLE);
                    super.onCreate(savedInstanceState);

                setContentView(R.layout.<view>); 

                builder = new AlertDialog.Builder(<class>.this);
                builder.setCancelable(true);
                builder.setMessage(<message>);
                builder.setInverseBackgroundForced(true);

        //call the <className> class to execute
}

    private class <className> extends AsyncTask<String, Void, String>{

    protected String doInBackground(String... params) {

    }
    protected void onPostExecute(String result){
        if(page.contains("error")) //when not subscribed
        {   
           if(builder!=null){
                builder.setNeutralButton("Ok",new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int whichButton){
                    dialog.dismiss();
                        if(!<condition>)
                        {
                        try
                        {
                        String pl = ""; 

                        mHelper.<flow>(<class>.this, SKU, RC_REQUEST, 
                        <listener>, pl);
                        }

                        catch(Exception e)
                        {
                        e.printStackTrace();
                        }
                    }  
                }
            });

            builder.show();
        }
    }

}
}

Answer:

with this globals variables idea,
I saved MainActivity instance in onCreate();
Android global variable

public class ApplicationController extends Application {

    public static MainActivity this_MainActivity;
}

and Open dialog like this. it worked.

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    // Global Var
    globals = (ApplicationController) this.getApplication();
    globals.this_MainActivity = this;
}

and in a thread, I open dialog like this.

AlertDialog.Builder alert = new AlertDialog.Builder(globals.this_MainActivity);
  1. Open MainActivity
  2. Start a thread.
  3. Open dialog from thread -> work.
  4. Click “Back button” ( onCreate will be called and remove first MainActivity)
  5. New MainActivity will start. ( and save it’s instance to globals )
  6. Open dialog from first thread –> it will open and work.

: )