Combo Box Value Change Listener

In the application, I have used a combo box that will be in autofocus mode. The application is used in a mobile device which has a scanner connected to it. whenever a value is scanned the filter attached to the combo box check the scanned value and place it in the combo box and i have written my logic in the Value change listener. The issue i’m facing here is that value change listener works when i leave the application or browser to another screen and came back the listener starts working. The same issue was faced with text field but over came that with “TextField.setValueChangeMode(ValueChangeMode.EAGER)”. Is there any thing like this for combo box