Problem after listbox clear()

I'm getting SelectedIndex value -1 after clearing a Listbox and repopulating it. Below is the code:

//..........
public Process[] processes;
private void Form1_Load(object sender, EventArgs e)
{
EnumProcs();
}
private void EnumProcs(){
processes = Process.GetProcesses();
foreach (Process process in processes)
{
//Get whatever attribute for process
listBox_processes.Items.Add(process.ProcessName.ToString());
listBox2.Items.Add(process.HandleCount.ToString());
}
}
private void listBox_processes_SelectedIndexChanged(object sender, EventArgs e)
{
listBox_processes.Items.Clear();
processes = null;
EnumProcs();
Process ProcessCurrent = processes[listBox_processes.SelectedIndex]; // ** I get -1 as SelectedIndex **
//.......

Above, I use EnumProcs() to Enumerate system processes and load their names into a Listbox. After 1st population in Form1_Load(), I call EnumProcs() when ever the user selects an item from the Listbox with the proccess names. In SelectedIndexChanged(), I clear() the Listbox before calling EnumProcs(). But when I click an item in the Listbox, SelectedIndex returns -1, though Listbox item count shows 50+.

How to fix this?

Thanks.

3 Replies

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Chetan Ranpariya8y ago
Accepted answer
When you clear and refill the listbox, the selection is lost. That's why the SelectedIndex becomes -1.
Kasun Lee8y ago
Sorry, I don't know if I'm misunderstanding the answer. But After I clear the Listbox, I fill it again calling EnumProc(), hence getting 50+ items in it when debugging. So how could SelectedIndex be -1 when the Listbox is filled?
Chetan Ranpariya8y ago
Because you are clearing the list box before using "listBox_processes.SelectedIndex" you are getting -1.

You should do "Process ProcessCurrent = processes[listBox_processes.SelectedIndex];" before "listBox_processes.Item.Clear();" so that you can get the selected item properly.