Helper to get System Window permission

SystemWindowUtil.java

import android.content.Context;
import android.content.Intent;
import android.os.Build;
import android.provider.Settings;

public class SystemWindowUtil {
  private final Context appContext;

  public SystemWindowUtil(Context appContext) {
    this.appContext = appContext;
  }

  public void askForPermission() {
    // Check if Android M or higher
    if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.M){
      // Show alert dialog to the user saying a separate permission is needed
      // Launch the settings activity if the user prefers
      Intent myIntent = new Intent(Settings.ACTION_MANAGE_OVERLAY_PERMISSION);
      appContext.startActivity(myIntent);
    }
  }

  public boolean havePermission() {
    return Build.VERSION.SDK_INT < Build.VERSION_CODES.M ||
        Settings.canDrawOverlays(appContext);
  }
}