Taking an Object from one Collection to another

Question

is this a correct way to move objects from one list to another?

private ObservableCollection<SomeObject> toBeProcessed = 
                                new ObservableCollection<SomeObject>();


public ObservableCollection<SomeObject> ToBeProcessed 
{
    get
    {
        return toBeProcessed ;
    }
    set
    {
        //implements INotifyProperyChanged:
        SetField(ref toBeProcessed , value, "ToBeProcessed"); 
    }
}


public void MoveSelected(ObservableCollection<SomeOject> SelectedObjects)
{
    foreach (var obj in SelectedObjects)
    {
        ToBeProcessed.Add(obj);
        SelectedObjects.Remove(obj);
    }
}

is this the right way? if yes, is there a better way?

Update, sorry figured that it cant be done in a foreach loop so change it to this

for (int i = SelectedObjects.Count - 1; i >= 0; i--)
{
    ToBeProcessed.Add(SelectedObjects[i]);
    SelectedObjects.RemoveAt(i);
}

is it still the right way?

this code will throw an exception `InvalidOperationException: Collection was modified; enumeration operation may not execute` at the foreach loop — Jehof, Oct 30 '13 at 06:53
@SriramSakthivel its public so from the class that has SelectedObjects — FPGA, Oct 30 '13 at 06:55
Collections within foreach loops are immutable http://stackoverflow.com/a/759985/1226915 — Wim Ombelets, Oct 30 '13 at 06:55
on a side note: there's something called a `ConcurrentDictionary` in c# that allows for such behavior, although in all fairness, this only works on multi-cpu systems. — Wim Ombelets, Oct 30 '13 at 07:01

score 2 · Accepted Answer · answered Oct 30 '13 at 07:55

2

Well, you could simply do:

foreach (var obj in SelectedObjects)
    ToBeProcessed.Add(obj);

SelectedObjects.ClearItems();

answered Oct 30 '13 at 07:55

sloth

99,095
21
171
219

score 1 · Answer 2 · answered Oct 30 '13 at 07:31

You cannot modify a collection when you go through it no matter with index or foreach. However, from your description, SelectedObjects here behaves more like a "temporary collection", which is selected from another collection of ToSelectObjects, so you may not need to remove objects from it, but after adding them into ToBeProcessed, foreach loop SelectedObjects again and remove them from ToSelectObjects...

Taking an Object from one Collection to another

2 Answers2