用户在CheckedListBox中检查了项目

Question

I have a CheckedListBox . I want to know when the user checked or unchecked an item. I tried using ItemCheck event but it fires even when an item is programmatically checked. How can I detect this?

Answer 1

Using the ItemCheck event handler is the correct method for detecting when the user ticks or un-ticks an item in the CheckedListBox . And yes, it will also fire when the item is checked/unchecked programmitically.

If you don't want the event fired when you set/unset items programmatically, you should remove the event handler before hand.

Assuming your event handler looks like this:

private void checkedListBox1_ItemCheck(object sender, ItemCheckEventArgs e)
{
    if (e.NewValue == CheckState.Checked)
    {
        Debug.Print("Checked");
    }
    else if (e.NewValue == CheckState.Unchecked)
    {
        Debug.Print("Un-Checked");
    }
}

Before you set/unset items programmatically, you should add the line:

this.checkedListBox1.ItemCheck -= this.checkedListBox1_ItemCheck;

and after the items have been set/unset you in code, re-add the event handler with:

this.checkedListBox1.ItemCheck += this.checkedListBox1_ItemCheck;