is this efficent?

gistfile1.java

class Dispatcher {
  private List data = new ArrayList();
  private List listeners = new ArrayList();

  public synchronized onNewData(byte[] newData){
     updateData()
     notifyListeners(newData)
  }

  public synchronized register(Listener l) {
    //send all current data to l
    l.sendAll(data);
    listeners.add(l);
  }

  private notifyListeners(byte[] newData) {
     for(l:listeners){
        l.sendData(newData)
     }
  }