Calling remove in foreach loop in Java

Question

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Answer 1

To safely remove from a collection while iterating over it you should use an Iterator.

For example:

List<String> names = ....
Iterator<String> i = names.iterator();
while (i.hasNext()) {
   String s = i.next(); // must be called before you can call i.remove()
   // Do something
   i.remove();
}

From the Java Documentation :

The iterators returned by this class's iterator and listIterator methods are fail-fast: if the list is structurally modified at any time after the iterator is created, in any way except through the iterator's own remove or add methods, the iterator will throw a ConcurrentModificationException. Thus, in the face of concurrent modification, the iterator fails quickly and cleanly, rather than risking arbitrary, non-deterministic behavior at an undetermined time in the future.

Perhaps what is unclear to many novices is the fact that iterating over a list using the for/foreach constructs implicitly creates an iterator which is necessarily inaccessible. This info can be found here