Java delete arraylist iterator

Question

I\'ve an ArrayList in Java of my class \'Bomb\'.

This class has a method \'isExploded\', this method will return true if the bomb has been exploded, else false.

Answer 1

No, you cannot remove inside an Iterator for ArrayList while iterating on it. Here's Javadoc extract :

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.

http://docs.oracle.com/javase/6/docs/api/java/util/ArrayList.html

Answer 2

You'll need to get the Bomb using next :

for (Iterator i = bombGrid.listIterator(); i.hasNext();) {
   Bomb bomb = (Bomb) i.next(); 
   if (bomb.isExploded()) i.remove();
}

Or if you can get an Iterator<Bomb> from your bombGrid (is it an ArrayList<Bomb> ?):

Iterator<Bomb> i = bombGrid.listIterator();
while (i.hasNext()) {
   Bomb bomb = i.next(); 
   if (bomb.isExploded()) i.remove();
}

This supposes your iterator supports remove, which is the case for example by the one given by an ArrayList.

Answer 3

If you use Java 5, use generics:

List<Bomb> bombGrid = ...;
for (Iterator<Bomb> i = bombGrid.iterator(); i.hasNext();) {
  if (i.next().isExploded()) {         
    i.remove();
  }
}