Android M Light and Dark status bar programmatically – how to make it dark again?

The solution posted by @Aracem is valid but, doesn’t work if you try change also the background color of the status bar. In my case I do it in the following way.

To enable windowLightStatusBar(programatically,inside a Utils class for example):

 public static void setLightStatusBar(View view,Activity activity){


            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {

                int flags = view.getSystemUiVisibility();
                flags |= View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR;
                view.setSystemUiVisibility(flags);
                activity.getWindow().setStatusBarColor(Color.WHITE); 
            }
}

To restore to StatusBar to the previous state:

  public static void clearLightStatusBar(Activity activity) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            Window window = activity.getWindow();
            window.setStatusBarColor(ContextCompat
                 .getColor(activity,R.color.colorPrimaryDark)); 
        }
    }

Restoring the color of the status bar is enough, it restores also the icons colors.
VERY IMPORTANT: The restore operation will not occur until the view used in setLightStatusBar(View view..) dissapears(that is, view.getVisibility()==GONE|INVISIBLE) from the screen.