Answers for "no of elements that are common in two lists"

find common elements in two lists python

list1 = [1,2,3,4,5,6]
list2 = [3, 5, 7, 9]
list(set(list1).intersection(list2))

get common elements from two lists

List<Integer> l1 = new ArrayList<Integer>();

l1.add(1);
l1.add(2);
l1.add(3);

List<Integer> l2= new ArrayList<Integer>();
l2.add(4);
l2.add(2);
l2.add(3);

System.out.println("l1 == "+l1);
System.out.println("l2 == "+l2);

List<Integer> l3 = new ArrayList<Integer>(l2);
l3.retainAll(l1);

    System.out.println("l3 == "+l3);