Question

I am looking for a data structure, optimized for search-operations (in the Java std-lib). I have to iterate over it several times, control every element and delete it in special cases. I have used a HashMap, but I always get following error:

for (Edge e : edges) {
    if (special case)
    edges.remove(e);
}

java.util.ConcurrentModificationException
at java.util.HashMap$HashIterator.nextEntry(HashMap.java:810)
at java.util.HashMap$KeyIterator.next(HashMap.java:845)
at package.name.TFinder.nN(TFinder.java:83)
at package.name.TFinder.fIT(TFinder.java:56)
at package.name.Main.main(Main.java:215)

Answer 1

From your description, you should be able to use HashMap for this. The key is to use iterator.remove() to delete entries:

for (Iterator<Map.Entry<Key,Value>> it = map.entrySet().iterator(); it.hasNext();)
{
    Map.Entry<Key,Value> entry = it.next();
    // process the entry
    if(need to delete the entry) 
    {
        it.remove();
    }
}