[SOLVED] Unable to add window ... -- permission denied for window type 2038

I'm trying to add a window in my android app but I'm facing with this issue.

I just started android development so I'm not sure what should I need to do. I did research but couldn't find the solution yet. This is Window.java file.

package serhatkaya.hp;

import android.content.Context;
import android.graphics.PixelFormat;
import android.os.Build;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.WindowManager;
import android.widget.Toast;

public class Window {

  private Context context;
  private WindowManager windowManager;
  private LayoutInflater layoutInflater;
  private View rootView;
  private WindowManager.LayoutParams windowParams;

  public Window(Context context) {
    this.context = context;
    this.windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
    this.layoutInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    this.rootView = layoutInflater.inflate(R.layout.window, null);

    this.windowParams = new WindowManager.LayoutParams(
        0,
        0,
        0,
        0,
        (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) ? WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY
            : WindowManager.LayoutParams.TYPE_PHONE,
        WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS |
            WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE |
            WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL |
            WindowManager.LayoutParams.FLAG_WATCH_OUTSIDE_TOUCH,
        PixelFormat.TRANSLUCENT);

    initWindowParams();
    initWindow();
  }

  private DisplayMetrics getCurrentDisplayMetrics() {
    DisplayMetrics dm = new DisplayMetrics();
    windowManager.getDefaultDisplay().getMetrics(dm);
    return dm;
  }

  private void calculateSizeAndPosition(WindowManager.LayoutParams params, int widthInDp, int heightInDp) {
    DisplayMetrics dm = getCurrentDisplayMetrics();
    params.gravity = Gravity.TOP | Gravity.LEFT;
    params.width = (int) (widthInDp * dm.density);
    params.height = (int) (heightInDp * dm.density);
    params.x = (dm.widthPixels - params.width) / 2;
    params.y = (dm.heightPixels - params.height) / 2;
    
  }

  private void initWindowParams() {
    calculateSizeAndPosition(windowParams, 300, 80);
  }

  private void initWindow() {
    rootView.findViewById(R.id.window_close).setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v) {
        close();
      }
    });

    rootView.findViewById(R.id.content_button).setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v) {
        Toast.makeText(context, "Adding notes to be implemented.", Toast.LENGTH_SHORT).show();
      }
    });
  }

  public void open() {
    try {
      windowManager.addView(rootView, windowParams);
    } catch (Exception e) {
      String d = e.getMessage();
      // Ignore exception for now, but in production, you should have some
      // warning for the user here.
    }
  }

  public void close() {
    try {
      windowManager.removeView(rootView);
    } catch (Exception e) {
      // Ignore exception for now, but in production, you should have some
      // warning for the user here.
    }
  }
}

AndroidManifest.xml

<?xml version='1.0' encoding='utf-8'?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android">

  <uses-feature
    android:name="android.hardware.telephony"
    android:required="false" />
  <uses-permission android:name="android.permission.INTERNET" />
  <uses-permission android:name="android.permission.READ_PHONE_STATE" />
  <uses-permission android:name="android.permission.READ_CALL_LOG" />
  <uses-permission android:name="android.permission.PROCESS_OUTGOING_CALLS" />

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

  <application android:allowBackup="true" android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name" android:roundIcon="@mipmap/ic_launcher_round"
    android:supportsRtl="true" android:theme="@style/AppTheme" android:usesCleartextTraffic="true">
    <activity
      android:configChanges="orientation|keyboardHidden|keyboard|screenSize|locale|smallestScreenSize|screenLayout|uiMode"
      android:exported="true" android:label="@string/title_activity_main"
      android:launchMode="singleTask" android:name=".MainActivity"
      android:theme="@style/AppTheme.NoActionBarLaunch">
      <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
      </intent-filter>
    </activity>
    <provider android:authorities="${applicationId}.fileprovider" android:exported="false"
      android:grantUriPermissions="true" android:name="androidx.core.content.FileProvider">
      <meta-data android:name="android.support.FILE_PROVIDER_PATHS"
        android:resource="@xml/file_paths" />
    </provider>
  </application>

</manifest>

When I try to open Window with open() function.

I'm facing the issue mentioned in the title.

I tried to add permission via androidmanifest.xml and also requesting from mainactivity like this:

  @RequiresApi(api = Build.VERSION_CODES.P)
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    String[] PERMISSIONS = {
        android.Manifest.permission.READ_PHONE_STATE,
        android.Manifest.permission.READ_CALL_LOG,
        android.Manifest.permission.PROCESS_OUTGOING_CALLS,
      android.Manifest.permission.FOREGROUND_SERVICE,
      android.Manifest.permission.SYSTEM_ALERT_WINDOW
    };

    ActivityCompat.requestPermissions(MainActivity.this, PERMISSIONS, PackageManager.PERMISSION_GRANTED);
    Window window = new Window(this);
    window.open();
  }

I faced the same issue.