Good day..

I have method that returns an ArrayList which consists of Sets of integers
ArrayList<Set<Integer>>
an example output :
[[77, 220], [35, 300], [45, 160, 310, 503], [101, 140, 250]]

I want to write a method that will receive the output from more than one instance and returns the duplicate integers between each instance...

PHP Code:
	   ArrayList<Set<Integer>> dups = new ArrayList<Set<Integer>>();
	 // then inside a for loop 
   		dups.retainAll(eachInstance.allNums());

   	//doesn't work an empty set will return
Any Suggestions ?