java - Add Collection (ArrayList) to ConcurrentQueue -

i have piece of code builds arraylist of custom class type ouput of function. then, attempt addall(collection) arraylist concurrentlinkeddeque. seems happen concurrentlinkeddeque ends containing arraylist.size() of last element in arraylist.

i have done various checks see if arraylist built , including proper elements, not seem see through problem. there peculiarities adding collections concurrentlinkeddeque's?

can try this

public class concurrentldtrial{     public static void main(string[] args) {         list<integer> = new arraylist<integer>();         a.add(2);         a.add(3);         concurrentlinkeddeque<integer> cd = new concurrentlinkeddeque<integer>(a);         system.out.println(cd);     } } 

the output [2, 3] , expected.

cast data structures appropriately custom class.