CODEWITHSUNDEEP
c#winformslistbox
modest and cute girl
modest and cute girl

Reputation: 785

listBox selectedItem issue

This works fine:

private void btnDelete_Click(object sender, EventArgs e)
{
    for (int i = 0; i < listBox1.SelectedItems.Count; i++) 
    {
        listBox1.Items.Remove(listBox1.SelectedItems[i].ToString());
        i--;
    }
}

But this doesn't work:

private void btnDelete_Click(object sender, EventArgs e)
{
    listBox1.Items.Remove(listBox1.SelectedItems);
}

Why is the second btnDelete_Click not working? I mean I select a line on my listBox1 with my mouse and then press the button. Doesn't the .Remove function recognize which line I selected? Even though I say .Remove(listBox1.SelectedItem), is it a must to have and selectedItem array? Isn't the word SelectedItems self-explanatory? And since I clicked the line on my listBox1 with my mouse, can't the program or the IDE understand which line is selected? Why do I still have to use SelectedItems[i]?

Upvotes: 2

Views: 909

Answers (5)

Bali C
Bali C

Reputation: 31231

The reason the second example does not work is because you are trying to pass multiple items in the form of a collection to be removed at once.

To remove an item you need to do it one at a time, hence why you need a loop.

Also, might I suggest using a ListView instead? I personally find them easier to use with many more options.

For example you could make your loop for a ListView with just this

foreach (ListViewItem item in listView1.SelectedItems)
{
    item.Remove();
}

If you are trying to remove only one item at a time that is selected then you do

listBox1.Items.Remove(listBox1.SelectedItem);

SelectedItem rather than SelectedItems, plural being the collection that it can't handle without a loop, singular being a single item that it can understand.

Upvotes: 1

JohnnBlade
JohnnBlade

Reputation: 4327

also change 

for (int i = 0; i < listBox1.SelectedItems.Count; i++) 
{
    listBox1.Items.Remove(listBox1.SelectedItems[i].ToString());
    i--;
}

to 

    for (int i = (listBox1.SelectedItems.Count - 1); i >= 0; i--)
    { 
      listBox1.Items.Remove(listBox1.SelectedItems[i]);
    }

and this should be 

 listBox1.Items.Remove(listBox1.SelectedItem);

Upvotes: 1

Stephan Bauer
Stephan Bauer

Reputation: 9249

ListBox.Items.Remove() expects one single item to remove while ListBox.SelectedItems returns a collection of items (SelectedObjectCollection) - even if only one item is selected!

You could write an extension method for removing all selected items:

public static class ListBoxExtension
{
    public static void RemoveSelectedItems(this ListBox source)
    {
        if(source==null) return;
        while(source.SelectedItems.Count!=0)
        {
            source.Items.Remove(source.SelectedItems[0]);
        }
    }
}

This can be used like that:

this.listbox1.RemoveSelectedItems();

Upvotes: 1

Dave New
Dave New

Reputation: 40002

listBox1.SelectedItems returns a collection of selected items. To remove an item, you can only pass in a single object in collection, using Remove(), OR an index to an object in the collection with RemoveAt().

Remove an object:

listBox1.Items.Remove(listBox1.SelectedItem);

Remove an object at index:

listBox1.Items.RemoveAt(5);

There is no RemoveRange() method, which is what you are looking for.

Upvotes: 1

user1530197
user1530197

Reputation:

I think SelectedItems needs indeks number. Maybe that's why you can't delete any item.

Upvotes: 1

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