如何检查所选项目是否已从先前选择的项目更改？

Question

I have a listbox in my winform, when an item in the listbox is selected, a value is placed into a textbox in the same Form. There my many items in my listbox which when selected, i want the text box to be empty so i can pass in the new value. How do i check is if the user has clicked on something other their initial selected item? i get the currently selected item like this below:

var selectedItem = (ReportItems)listbox.selectedItem

Answer 1

You can add a global variable for your ReportItems and call it 'selItem'.

After the user changed the selected Item you check the "new" selectedItem with the 'selItem'-variable.. i don't think that a listbox has a method that can check if the selection has changed from the previous one..

Answer 2

You can use the SelectedIndexChanged event on your ListBox . You can create an event handler for this event to determine when the selected index in the ListBox has been changed. This can be useful when you need to display information in other controls based on the current selection in the ListBox. You can use the event handler for this event to load the information in the other controls.

See MSDN documentation: link

Answer 3

I'm not sure if there is a reason you're not leveraging the SelectionChanged event of the ListBox or not but you should be if you're not. Further, determining if it's different than the initially selected item should be pretty straight forward because you can save the initially selected item in a private variable in your form and compare every time the method handler for SelectionChanged fires.

Other than this, there's not much more I can suggest because your questions isn't terribly clear and there is no code to look at.

Answer 4

My solution was to always clear the textbox first. So as soon as a user selects an item in the listview, rather than populating the textbox straight away, clear the textbox before populating it.

clearText(); is called soon as a listbox item is clicked.

    public void clearText()
    {
        textBox1.Clear();
        textBox2.Clear();
        textBox3.Clear();
        textBox4.Clear();
        textBox5.Clear();
        textBox6.Clear();
        textBox7.Clear();
        textBox8.Clear();
        textBox9.Clear();
        textBox10.Clear();
        textBox11.Clear();
        textBox12.Clear();
    }