Java: How to remove elements from a list while iterating over/adding to it

Question

This question is a more special case of the problem described (and solved) in this question.

I have two methods, stopAndRemove(ServerObject server) and a close() met

Answer 1

When I've done this before, I always used the "old school" LinkedList collection, an Iterator, and the Iterator.remove() method to remove the current item.

Answer 2

Refactor out all the ServerObject stopping code from stopAndRemove into a private stopServer method, and then do the removal separately in stopAndRemove and closeCurrentlyOpen. Then you can use a ListIterator to remove them (or just stop them all in a for loop and clear the list at the end).

Answer 3

... removing files that aren't XML from a directory list...

List<File> files = Arrays.asList(dir.listFiles());

Iterator<File> i = files.iterator();

while (i.hasNext()) {
    File file = i.next();
    if (!file.getName().endsWith(".xml")) {
        i.remove();
    }
}

Answer 4

Split off a method stop() from stopAndRemove(). Then write the loop with an explicit iterator, do the stop and then iterator.remove().

"and" in a method name is a code smell.

Answer 5

Similar to firebird84. But u can use removeAll(Collection c) api

for(String exitingPermission : existingPermissions){                
    //remove all permissions for the screen and add the new ones
    if(exitingPermission.split("_")[0].equals(screen)){
        removePermissions.add(exitingPermission);
    }
 }
existingPermissions.removeAll(removePermissions);

Answer 6

Perhaps this is the wrong way to do it, but I always create a removal collection, which contains indexes or references to the objects that need to be removed. I then iterate over that collection and remove those indexes/objects from the original collection. Probably not the most efficient but it got the job done.

Instead of

for(Collection things : thing)  
    things.remove(thing)

I use

Collection toRemove = new LinkedList();
for(things : thing)
    toRemove.add(thing);

for(toRemove : thing)
    things.remove(thing)