I've stumbled upon this code, which throws a ConcurrentModificationException
ArrayList<String> list = new ArrayList<String>(Arrays.asList("a", "b", "c", "d"));
for (String s : list) {
if (s.equals("a"))
list.remove(s);
}
If you add an Iterator and use a while-loop, the code works fine:
ArrayList<String> list = new ArrayList<String>(Arrays.asList("a", "b", "c", "d"));
Iterator<String> iter = list.iterator();
while (iter.hasNext()) {
String s = iter.next();
if (s.equals("a")) {
iter.remove();
}
}
I dont understand, why it is necessary, to use Iterator<String>
in this case.
Is it because of the ArrayList not having some sort of ability to get iterated, altough it is a subclass of Collection?
Is it necessary to use the while-loop, or could you produce a version with a for-loop?