Find same object in two arraylist

Question

List A={2,3,3} List B={2,3,5}

I want to get only {2,3} to do the gcd

I tried to use retainall() but result is {2,3,3}

public static int gcd(ArrayList<Integer> A,ArrayList<Integer> B)
{ //A={2,3,3},B={2,3,5}
    A.retainAll(B);
    System.out.println(A);
}

You haven't specified the task clearly enough, that multiple occurrences in both lists are essential, e.g. from `{2,3,3,5}` and `{3,3,7}` you expect `{3,3}`. So, you're getting answers that are correct, but won't help you. — Ralf Kleberhoff, Mar 14 '22 at 08:53

score 2 · Answer 1 · answered Mar 14 '22 at 08:45

2

I suggest to make use of Set, e.g. HashSet.

In a set, there are no duplicate values.

Set<Integer> set = new HashSet<Integer>(A.retainAll(B));

Also, method params use lowerCase naming.

answered Mar 14 '22 at 08:45

Remo

For the greatest common divisor (mentioned as a side-note by the OP), multiple occurrences are essential. So, the `Set` approach won't work. – Ralf Kleberhoff Mar 14 '22 at 08:50
Thx, for pointing out, I am aware of this. Out of the question (well there is not even a clear one), I only got that the author needed a distinct result out of 2 Array lists. – Remo Mar 14 '22 at 08:59

score 0 · Answer 2 · edited Mar 14 '22 at 09:19

0

you can use contains(Object o) method. Returns true if this list contains the specified element. ArrayList

edited Mar 14 '22 at 09:19

Derrick

answered Mar 14 '22 at 08:49

Abaytan99

2 Answers2