LinkedList and ConcurrentModification Exception problem

[Branko Santo]

I am sorry to post such lengthy code but I just can't get it to work.
I load up a LinkedList form disk and sort it and try to access the objects inside, but it throws the Exception. Really bummed I don't know what to do.
I have bolded the trace to exception, any help would be great!

Thanks!

    
    private void loadSezona()
    {
        try
        {
            File file = new File("C:/Kladionica/sezona.dat");
            if(file.isFile())
            {
                FileInputStream fis = new FileInputStream("C:/Kladionica/sezona.dat");
                ObjectInputStream obj_in = new ObjectInputStream(fis);
                sezona = (LinkedList<Game> :wink: obj_in.readObject();
                fis.close();
                obj_in.close();
                Comparator c = new Comparator()
                {
                    public int compare(Object o1, Object o2)
                    {
                        Game game1 = (Game)o1;
                        Game game2 = (Game)o2;
                        return (game1.getDanas()).compareTo(game2.getDanas());
                    }
                };
                Collections.sort((sezona), c);
                [B]updateGames[/B]();
            }
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
    }
    
    
    public void [B]updateGames[/B]()
    {
        Date date = getLastDate();
        Iterator iterator = sezona.iterator();
        while(iterator.hasNext())
        {
            [B]Game game = (Game)iterator.next(); [/B]   //ConcurrentModificationException here 
            if(game.getDanas().equals(date))
            {
                sezona.remove(game);
            }
        }
        DatabaseUpdate dbUpdate = new DatabaseUpdate(date, sezona);
    }
 

[Jesper de Jong]

Do you understand what ConcurrentModificationException means? Look up the API documentation for it.

You can't iterate over a List and modify the list at the same time. Instead of this:

while(iterator.hasNext())
{
    Game game = (Game)iterator.next();    //ConcurrentModificationException here 
    if(game.getDanas().equals(date))
    {
        sezona.remove(game);
    }

Try this, call remove() on the iterator instead of on the collection:

while(iterator.hasNext())
{
    Game game = (Game)iterator.next();
    if(game.getDanas().equals(date))
    {
        // Remove using iterator instead of directly from collection
        iterator.remove();
    }

[Ernest Friedman-Hill]

Don't use sezona.remove(game). Use iterator.remove() . Not only will the exception go away, but the performance will be much better for long lists. You can't call add() or remove() on a Collection while you're iterating over it, or the Iterator will throw an exception, as you found out.

[Anupam Bhatt]

Well that solves a frequently asked interview question too !

[Branko Santo]

Thanks people!!!

I know what the exception did, but the problem is I saw no problem with the code I already had something like that, but it must be that last time I was using something like you did.

Anyways really thanks!!!

A million