Hi@MD,
The most straightforward way to convert a set to a list is bypassing the set as an argument while creating the list. This calls the constructor and from there onwards the constructor takes care of the rest.
import java.util.*;
public class Main {
    public static void main(String[] args)
    {
        Set<Integer> a = new HashSet<>();
        a.add(1);
        a.add(2);
        a.add(3);
        a.add(1);
     List<Integer> arr = new ArrayList<>(a);
     System.out.println(arr);
     System.out.println(arr.get(1));
    }
}
Hope this helps!
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Thanks!