How to remove elements from LinkedList with nested iterators in java

user1796659 :

I am trying to remove duplicate elements from an unordered linked list in Java (a question from Cracking the Coding Interview).

I am using nested iterators over the same List object, but I get a ConcurrentModificationException when I remove an item. This is my code:

Iterator<String> i = list.iterator();   
String curr;
while (i.hasNext()) {
    curr = i.next();
    Iterator<String> j = list.iterator();
    while (j.hasNext()) {
        String runner = j.next();
        if (curr == runner){
            j.remove();
        }
    }
}

The solution in the book uses a LinkedListNode object, which makes it possible to just change the pointers of the nodes, but is there any way to solve this using java.util.LinkedList only?

EDIT : The challenge was to do this without using a temporary buffer, otherwise an additional list would do the trick.

Golov Pavel :

If you will not use iterators or foreach cycles, you will not receive ConcurrentModificationException. For example, you can do it like this:

List<Integer> list = new LinkedList<>(Arrays.asList(1, 2, 1, 2, 3));

for (int i = 0; i < list.size() - 1; i++) {
    for (int j = i + 1; j < list.size(); j++) {
        if (list.get(i).equals(list.get(j))) {
            list.remove(j);
            j--;
        }
    }
}

System.out.println(list); // [1, 2, 3]