list - How to add listener on ArrayList in java -

i want create own implementation of arraylist in java, can listen when list changing , action when happens. have read, understand can't extend arraylist , add listener.

i want use mylist in class variable public modifier, users can change directly , done action when changes it.

class mylist extends arraylist<object>.... {  ... }  class useofmylist {  public mylist places = new mylist<object>();  places.add("buenos aires");  //and able  list cities = new arraylist<object>();  cities.add("belmopan");  places = cities; 

so how create , when add,remove or pass list mylist action performed?

you're not going able extending arraylist, has no built-in notification mechanism (and, further, because has been declared final , cannot extended). however, can achieve desired result creating own list implementation , adding "listener" functionality vis vis add() , remove() methods:

 class mylist<t>{      private arraylist<t> list;       public mylist(){          list = new arraylist<>();      ...      }      public void add(t t){          list.add(t) {          //do other things want when items added           }      public t remove(t t){           list.remove(t);           //do other things want when items removed