Permission denied for window type 2002 in Android Studio

Question

Today I installed latest version of Android Studio

I am learning Floating Widgets in Android

I started with applying this example

https://www.spaceotechnologies.com/android-floating-widget-tutorial/

it compiles ok

but when I run it in the emulator it crashes

giving me this error

08-28 22:52:02.932 7400-7400/com.asmgx.MyApp.MyApp E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.asmgx.MyApp.MyApp, PID: 7400
    java.lang.RuntimeException: Unable to create service com.asmgx.MyApp.MyApp.FloatWidgetService: android.view.WindowManager$BadTokenException: Unable to add window android.view.ViewRootImpl$W@7c93828 -- permission denied for window type 2002
        at android.app.ActivityThread.handleCreateService(ActivityThread.java:3544)
        at android.app.ActivityThread.access$1300(ActivityThread.java:199)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1666)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
     Caused by: android.view.WindowManager$BadTokenException: Unable to add window android.view.ViewRootImpl$W@7c93828 -- permission denied for window type 2002
        at android.view.ViewRootImpl.setView(ViewRootImpl.java:822)
        at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:356)
        at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:93)
        at com.asmgx.MyApp.MyApp.FloatWidgetService.onCreate(FloatWidgetService.java:36)
        at android.app.ActivityThread.handleCreateService(ActivityThread.java:3532)
        at android.app.ActivityThread.access$1300(ActivityThread.java:199) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1666) 
        at android.os.Handler.dispatchMessage(Handler.java:106) 
        at android.os.Looper.loop(Looper.java:193) 
        at android.app.ActivityThread.main(ActivityThread.java:6669) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858) 

I tried resolving the issue and found this link

Unable to add window android.view.ViewRoot$W@44da9bc0 -- permission denied for this window type

they suggested adding this line to the manifest, which already added

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

anyone know why am i getting this?

PS. I used emulator with Android 28 and another with android 27

Answer 1

This is occurring because the targetSdkVersion in the example and your targetSdkVersion are different. Use the flag TYPE_APPLICATION_OVERLAY instead of TYPE_PHONE in WindowManager.LayoutParams:

WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY 

Answer 2

This worked for me.. I'm sure it can be simplified, but it works perfectly otherwise.
Simply replace TYPE_PHONE with TYPE_APPLICATION_OVERLAY if (and only if) user is equal or above Oreo:

final WindowManager.LayoutParams params;
    if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {
        params = new WindowManager.LayoutParams(
                WindowManager.LayoutParams.WRAP_CONTENT,
                WindowManager.LayoutParams.WRAP_CONTENT,
                WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY,
                WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
                PixelFormat.TRANSLUCENT);
    } else {
        params = new WindowManager.LayoutParams(
                WindowManager.LayoutParams.WRAP_CONTENT,
                WindowManager.LayoutParams.WRAP_CONTENT,
                WindowManager.LayoutParams.TYPE_PHONE,
                WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
                PixelFormat.TRANSLUCENT);
    }

OR do this in simple way

    int LAYOUT_FLAG;
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            LAYOUT_FLAG = WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY;
        } else {
            LAYOUT_FLAG = WindowManager.LayoutParams.TYPE_PHONE;
        }

        final WindowManager.LayoutParams params = new WindowManager.LayoutParams(
                WindowManager.LayoutParams.WRAP_CONTENT,
                WindowManager.LayoutParams.WRAP_CONTENT,
                LAYOUT_FLAG,
                WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
                PixelFormat.TRANSLUCENT);