/** * Adds <tt>WebRtcDataStreamListener</tt> to the list of listeners. * * @param listener the <tt>WebRtcDataStreamListener</tt> to be added to the listeners list. */ public void addChannelListener(WebRtcDataStreamListener listener) { if (listener == null) { throw new NullPointerException("listener"); } else { synchronized (listeners) { if (!listeners.contains(listener)) { listeners.add(listener); } } } }