Question

I would like to add elements in a loop to a list in such a way that the loop body will execute also for them. I know that this technique is very common in order to prevent ConcurrentModificationException:

List<Element> thingsToBeAdd = new ArrayList<Element>();
for(Iterator<Element> it = mElements.iterator(); it.hasNext();) {
    Element element = it.next();
    if(...) {  
         //irrelevant stuff..
        if(element.cFlag){
            // mElements.add(new Element("crack",getResources(), (int)touchX,(int)touchY));
            thingsToBeAdd.add(new Element("crack",getResources(), (int)touchX,(int)touchY));
            element.cFlag = false;
       }           
   }
}
mElements.addAll(thingsToBeAdd );

Unfortunately it doesn’t execute the loop for the new elements.

Edit:

List<Element> thingsToBeAdd = new ArrayList<Element>();
for(Iterator<Element> it = mElements.iterator(); it.hasNext();) {
    Element element = it.next();
    if(...) {  
        //irrelevant stuff..
        if(element.cFlag){
            // mElements.add(new Element("crack",getResources(), (int)touchX,(int)touchY));
            thingsToBeAdd.add(new Element("crack",getResources(), (int)touchX,(int)touchY));
            element.cFlag = false;
       }           
   }
   mElements.addAll(thingsToBeAdd );
}

This will result in ConcurrentModificationException.

Answer 1

I achived my goal using recursion:

private List<Element> executeForEachElement(List<Element> oldList)
    List<Element> newElements = new LinkedList<Element>();
    for (Element elem : oldList {
            newElements.addAll(generateNewElements(elem));
    }
    if (!newElements.isEmpty()) {
        oldList.addAll(executeForEachElement(newElements));
    }

    return oldList;
}