Android: removing elements from list with iterator

Question

     private void removeLettersFromMakeWords(List<String> a, List<String> b){
     Iterator<String> i = a.iterator();

     for(String s:b)
         while (i.hasNext()) {
            Object o = i.next();

            if(o.toString().equals(s)){
                i.remove();
                break;
            }
         }
    }

I use an iterator to loop through my list and remove an element from the list if there is a match. For example: if a = [a, y, f, z, b] and b = [a, f] --> the output will be a = [y, z, b]

Problem is if a = [a, y, f, z, b] and b = [f, a] --> the output will be a = [a, y, z, b] and the iterator doesn't remove the [a] value in the beginning. Is there a way to reset the iterator so that every time I break the iterator starts from the beginning? Or is there a better way to solve this issue?

The issue is that you never reset the iterator. You could simply create a new iterator for each string of b. However, I would recommend to simply use a.removeAll(b) instead of all that code. — njzk2
– njzk2, Commented Nov 4, 2014 at 17:02

matiash · Accepted Answer · 2014-11-04 17:05:31Z

2

You cannot "reset" an iterator, but you can just get a new one whenever you want to iterate from the beginning again. Like this:

if (o.toString().equals(s)) {
     i.remove();
     i = a.iterator();
     break;
}

Edit: as @njzk2 says in his comment, there are better (built-in) methods for doing this.

answered Nov 4, 2014 at 17:05

matiash

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2 Comments

user2456977 Over a year ago

this is great! and ya the removeAll is much simpler

matiash Over a year ago

@user2456977 Indeed. However, since the subject was "removing elements from list with iterator"... :)

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