Question

i have this ArrayList ID that contains objects:

0
10
10
9
8
3
11
6
10
1
7
13
7
7

After one occurrence of integer, i want that integer is added to another list (example visited) and the checking process stop. How to solve this? Must I change the type ArrayList ID to another java collection?

Answer 1

import java.util.HashSet;

public class Test {

    private static final HashSet<Integer> onetimevisit = new HashSet<Integer>();
    private static final HashSet<Integer> alreadyVisited = new HashSet<Integer>();

    public static void addVisitor(Integer visitorId){
        if(onetimevisit.contains(visitorId))
            alreadyVisited.add(visitorId);
        else
            onetimevisit.add(visitorId);
    }
}