Remove duplicate values from the Stack in Java - arrays

Question

I made a method that remove any duplicate in the Stack and return the resulting stack sorted in ascending order. For example, look at the main function, it should output as 1, 3, 4, 7. But it outputs the original stack data instead, which is incorrect. Any suggestions?
import java.util.ListIterator;
import java.util.Stack;
public class removeDoubleInStack {
public static Stack<Integer> removeDouble(Stack<Integer> s) {
Stack<Integer> tempStack = new Stack<Integer>();
ListIterator<Integer> iter = s.listIterator();
while(iter.hasNext()) {
int tempNext = iter.next();
if(tempNext != iter.next())
tempStack.add(tempNext);
}
return tempStack;
}
public static void main(String[] args) {
Stack<Integer> s = new Stack<Integer>();
s.add(1);
s.add(3);
s.add(3);
s.add(4);
s.add(7);
s.add(7);
removeDouble(s);
System.out.println(s);
}
}

Answer 1

As you can see in the Doc, there is nothing similar to remove duplicates
https://docs.oracle.com/javase/6/docs/api/java/util/Stack.html
but you can do it when:
1- get elements of the stack as Enumeration
2- turn Enumeration into List
3- add list to Set
4- clear stack
5- add set to stack
Example:
final Stack<Integer> ms = new Stack<Integer>();
ms.add(0);
ms.add(0);
ms.add(0);
ms.add(1);
ms.add(1);
ms.add(1);
ms.add(3);
ms.add(56);
System.out.println("Before clean:\n" + ms);
final Set<Integer> s = new HashSet<Integer>(Collections.list(ms.elements()));
ms.clear();
ms.addAll(s);
System.out.println("After clean:\n" + ms);

Answer 2

System.out.println(s) only prints s object that initialized before. removeDouble(s) doesn't have any impact unless you create new object of Stack or reinitialized...
public static void main(String[] args){
Stack<Integer> s = new Stack<Integer>();
s.add(1);
s.add(3);
s.add(3);
s.add(4);
s.add(7);
s.add(7);
Stack<Integer> tempStack = removeDouble(s); // create new object
System.out.println(tempStack);
}