Show dialog alert from a non-activity class in android

Question

I want to show an Alert Dialog via AlertDialogManager class to a non-activity class DeviceAdminReceiverSample's method onDisabled, but whenever I call alertDialog via that method it generates error with following text

Error

06-12 12:01:19.923: E/AndroidRuntime(468): FATAL EXCEPTION: main
06-12 12:01:19.923: E/AndroidRuntime(468): java.lang.RuntimeException: Unable to start           
receiver com.android.remotewipedata.DeviceAdminReceiverSample:   
android.view.WindowManager$BadTokenException: Unable to add window -- token null is not   
for an application

I know the issue is with context thing but I don't know what to put there so that it work, I tried this, getApplicationContext() but all vain. My code for both classes is below

AlertDialogManager

public class AlertDialogManager {

public void showAlertDialog(Context context, String title, String message,
        Boolean status) {
    final AlertDialog alertDialog = new AlertDialog.Builder(context).create();
    alertDialog.setTitle(title);
    alertDialog.setMessage(message);

    if (status != null)
        alertDialog.setButton("OK", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int which) {
                alertDialog.dismiss();
            }
        });
    alertDialog.show();
}

}

DeviceAdminReceiverSample

public class DeviceAdminReceiverSample extends DeviceAdminReceiver {
static final String TAG = "DeviceAdminReceiver";
AlertDialogManager alert = new AlertDialogManager();

/** Called when this application is no longer the device administrator. */
@Override
public void onDisabled(Context context, Intent intent) {
    super.onDisabled(context, intent);
    Toast.makeText(context, R.string.device_admin_disabled,
            Toast.LENGTH_LONG).show();
    // intent.putExtra("dialogMessage", "Device admin has been disabled");
    // intent.setClass(context, DialogActivity.class);
    // intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    // context.startActivity(intent);
    alert.showAlertDialog(context, "Alert",
            "Device admin has been disabled", true);
}

create a DialogActivity for that. – Chintan Rathod Jun 12 '13 at 07:09 — Chintan Rathod, Jun 12 '13 at 07:09
Use activity Object instead of context object. – Ajay Feb 14 '14 at 08:01 — Ajay, Feb 14 '14 at 08:01

score 42 · Answer 1 · edited Nov 07 '19 at 04:44

42

Just add this before your alertDialog.show();

alertDialog.getWindow().setType(WindowManager.LayoutParams.TYPE_SYSTEM_ALERT);

or try following if above didn't work:

alertDialog.getWindow().setType(WindowManager.LayoutParams.TYPE_APPLICATION_PANEL);

and use this permission:

<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />

edited Nov 07 '19 at 04:44

kevoroid

5,052
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answered Jul 04 '15 at 14:18

Eliran Kuta

4,148
3
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1

Thanks, it's working. Your answer should be vote up. – VAdaihiep Aug 31 '15 at 03:44
2

Very good finding. Thank you. Adding to this solution, as per documentation `Allows an application to open windows using the type TYPE_SYSTEM_ALERT, shown on top of all other applications. Very few applications should use this permission; these windows are intended for system-level interaction with the user.` So we also need to take care while using this solution. – Pankaj Kumar Oct 09 '15 at 06:33
Had the same issue, resolved it using this way. Thanks – darthvading Oct 20 '15 at 10:01
1

Bad solution, because hardBackButton will close activity, but not dialog. – Dmitry Nelepov Mar 18 '16 at 15:16
3

I think we should not use this.. As it will show alert in complete android system no matter in which application user is.. and second on touching outside the alert ,it is not dismiss. and if you want to do any action for your app then it could be crash – Jishant Apr 20 '16 at 11:30

score 15 · Accepted Answer · edited May 23 '17 at 12:02

15

The problem is 'You can show AlertDialogs from Activity only'. This is not an issue of context.

Although this is not a good idea to show dialog from receiver (better is to use Notification), But if you want to do so you can create an Activity as dialog and show

edited May 23 '17 at 12:02

Community

1
1

answered Jun 12 '13 at 07:10

Pankaj Kumar

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Yes, indeed, it's impossible to show AlertDialog outside of Activity, here is how I solved this issue: https://medium.com/@vapoyan/android-show-allertdialog-before-the-application-starts-80588d6f2dda – Viktor Apoyan Aug 10 '20 at 06:49

score 10 · Answer 3 · answered Jun 08 '16 at 21:33

If you always want to get the current activity from anywhere in the app you can register an ActivityLifecycleCallback on your Application instance.

Here's an untested implementation that might get you closer.

public class TestApp extends Application {

    private WeakReference<Activity> mActivity = null;

    @Override
    public void onCreate() {
        super.onCreate();
        registerActivityLifecycleCallbacks(new ActivityLifecycleCallbacks() {
            @Override
            public void onActivityCreated(Activity activity, Bundle savedInstanceState) {
                mActivity = new WeakReference<Activity>(activity);
            }

            @Override
            public void onActivityDestroyed(Activity activity) {
                mActivity.clear();
            }

            /** Unused implementation **/
            @Override
            public void onActivityStarted(Activity activity) {}

            @Override
            public void onActivityResumed(Activity activity) {}
            @Override
            public void onActivityPaused(Activity activity) {}

            @Override
            public void onActivityStopped(Activity activity) {}

            @Override
            public void onActivitySaveInstanceState(Activity activity, Bundle outState) {}
        });
    }

    public Activity getCurrentActivity() {
        return mActivity.get();
    }

}

Then to use this throughout your app you would do some call like this ...

Activity activity = ((TestApp)getApplicationContext()).getCurrentActivity();

The advantages are you can always keep track of your current activity, however its a little too overkill for just handling Dialogs from within the Activity.

@Chris Sullivan This is not working when moving from one activity to another, as the second activity will be initialized before the first is cleared. — Sakkeer Hussain, Mar 05 '19 at 14:56
@SakkeerHussain yes, 1st activity is destroyed after both are created. So, it would clear the mActivity — StackExploded, Jul 24 '19 at 15:46
@StackExploded I found a solution for that by adding a check to existing activity and to be deleting activity is equal or not, the clear operation would skip if both are not matching — Sakkeer Hussain, Jul 24 '19 at 16:22
yes, i did it mysel. Can check if `activity.hashCode()` are equal — StackExploded, Jul 25 '19 at 09:07
@Chris Sullivan, you can declare the Activity in the onActivityResumed method, and clear it in the onActivityPaused method. This will fix the issue — Salam El-Banna, Nov 18 '22 at 20:25

score 1 · Answer 4 · answered Jun 12 '13 at 07:12

call this method in activity class

public static void showAlert(Activity activity, String message) {

        TextView title = new TextView(activity);
        title.setText("Title");
        title.setPadding(10, 10, 10, 10);
        title.setGravity(Gravity.CENTER);
        title.setTextColor(Color.WHITE);
        title.setTextSize(20);

        AlertDialog.Builder builder = new AlertDialog.Builder(activity);
        // builder.setTitle("Title");
        builder.setCustomTitle(title);
        // builder.setIcon(R.drawable.alert_36);

        builder.setMessage(message);

        builder.setCancelable(false);
        builder.setNegativeButton("OK", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int id) {
                dialog.cancel();

            }

        });

        AlertDialog alert = builder.create();
        alert.show();
    }

Thanks, this concept is help me a lot, – Atiar Talukdar Apr 08 '17 at 07:47 — Atiar Talukdar, Apr 08 '17 at 07:47

score 0 · Answer 5 · answered Apr 04 '18 at 05:01

Here's what I made and use:

myDialog.java:

import android.app.Activity;
import android.content.DialogInterface;
import android.support.v7.app.AlertDialog;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.TextView;

public class myDialog {
    private Activity mActivity;

    myDialog(Activity a) {
        this.mActivity = a;
    }

    @SuppressWarnings("InflateParams")
    public void build(String title, String msg) {
        LayoutInflater inflater = LayoutInflater.from(mActivity);
        View subView = inflater.inflate(R.layout.dialog_box_text, null);
        final TextView message = subView.findViewById(R.id.message);
        message.setText(msg);
        AlertDialog.Builder builder = new AlertDialog.Builder(mActivity);
        builder.setTitle(title);
        builder.setView(subView);
        builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();
            }
        });
        AlertDialog alert = builder.create();
        alert.show();
    }
}

dialog_box_text.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:weightSum="1"
    android:orientation="horizontal">
    <TextView
        android:id="@+id/message"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="  "
        android:maxLines="1"
        android:textColor="@color/colorBlack" />
</LinearLayout>

Example code:

public class MainActivity extends AppCompatActivity {
    private myDialog md;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        md = new myDialog(this);

...

        md.build("Title", "Message");

score -2 · Answer 6 · answered Apr 09 '20 at 18:23

You can define a public Context var in the MainActivity with initial value (this); As show here:

public class MainActivity< alertdail > extends AppCompatActivity {

    ////////////////////////////////////////////////////////////
    //Public var refers to Main Activity:
    Context mainActivity = this;
    ////////////////////////////////////////////////////////////

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate ( savedInstanceState );
        setContentView ( R.layout.activity_main );
        AlertDialogManager alert  =new AlertDialogManager ();
alert.showAlertDialog ( this,"Title","Message",true );


     }


    public class AlertDialogManager {

        public void showAlertDialog(Context context, String title, String message,
                                    Boolean status) {
            final AlertDialog alertDialog = new AlertDialog.Builder ( mainActivity ).create ( );
            alertDialog.setTitle ( title );
            alertDialog.setMessage ( message );

            if (status != null)
                alertDialog.setButton ( "OK", new DialogInterface.OnClickListener ( ) {
                    public void onClick(DialogInterface dialog, int which) {
                        alertDialog.dismiss ( );
                    }
                } );
            alertDialog.show ( );
        }

        public void showAlertDialog(Context c) {
        }
    }


    public class DeviceAdminReceiverSample extends DeviceAdminReceiver {
        static final String TAG = "DeviceAdminReceiver";
        AlertDialogManager alert = new AlertDialogManager ( );

        /**
         * Called when this application is no longer the device administrator.
         */
        @Override
        public void onDisabled(Context context, Intent intent) {
            super.onDisabled ( context, intent );
            Toast.makeText ( context, R.string.device_admin_disabled,
                    Toast.LENGTH_LONG ).show ( );
            // intent.putExtra("dialogMessage", "Device admin has been disabled");
            // intent.setClass(context, DialogActivity.class);
            // intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
            // context.startActivity(intent);
            alert.showAlertDialog ( context, "Alert",
                    "Device admin has been disabled", true );
        }
    }
}

This way of sharing the activity context could end up in memory leaks. — arjoan, Apr 09 '20 at 18:50

lighthouse64 · Answer 7 · 2017-09-27T23:12:29.873

Here's a quick method of properly performing this task that has done the job for me. Basically, what you would do is just create a new thread.

Declare a public and static variable with a type that matches the original activity class.

public static Activity1 activity;

Activity1 is the class that the variable resides in.

Upon calling the method onCreate();, set the variable to be equal to the context of the activity, otherwise known as this.

Example:

@Override 
    protected void onCreate( Bundle savedInstanceState ) {
    super.onCreate( savedInstanceState );
    activity = this;
}

3. Since we now have the context of the activity, we can use it to create a function with an alert dialog by using the runOnUiThread(); method inside of the function that will call the alert dialog. We would use a new Runnable() for the runnable action required for runOnUiThread();, and to have the alert dialog actually open, we would override the run function of a runnable item and place the code for the alert dialog in there.

Example function:

public static void exampleDialog(){
Activity1.activity.runOnUiThread(new Runnable){
@Override
    public void run(){
    //alert dialog code goes here.  For the context, use the activity variable from Activity1.
        }
    }
}

Hope this helps :)

using the static variable of the activity causes the memory leaks, not an efficient solution to the problem — Adeel Javed, Apr 13 '19 at 16:46

Show dialog alert from a non-activity class in android

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