Calling next on an Iterator once vs multiple times

Question

Why this first version of the code does not work

          // returns the longest string in the list (does not work!)

         public static String longest         


        

Answer 1

Count the number of times next() is called in the first snipped compared to the second:

while (itr.hasNext()) {
    if (itr.next().length() > longest.length()) {
        ^^^^^^^^^^
        longest = itr.next();
                  ^^^^^^^^^^
    }
}

compared to

while (itr.hasNext()) {
    String current = itr.next();
                     ^^^^^^^^^^
    if (current.length() > longest.length()) {
        longest = current;
    }
}

Every time you call itr.next(), you advance the iterator another token. So in the first snippet, you only store/compare every other token, while in the second snippet you store/compare the same token.