Developers could use the addEventListener and removeEventListener methods of the org.zkoss.zk.ui.Component interface to dynamically add or remove an event listener. As illustrated below, the event listener to be added dynamically must implement the org.zkoss.zk.ui.event.EventListener interface.

void init(Component comp) {
    ...    
    comp.addEventListener("onClick", new MyListener());    
    ...    
}
class MyListener implements org.zkoss.zk.ui.event.EventListener {
    public void onEvent(Event event) throws UiException {    
        ...//processing the event        
    }    
}