How to determine if an item in a ListBox is selected.

To determine if an item in a ListBox is selected, you can follow these steps:

1. Retrieve the SelectedIndex property value of a ListBox. If the SelectedIndex is -1, it means that no item is selected.
2. Retrieve the value of the SelectedItem property from the ListBox. If SelectedItem is null, it means that no item has been selected.
3. Use the GetSelected method of the ListBox to determine if a specific index item is selected. This method takes an index as a parameter and returns a Boolean value indicating whether the item is selected.

Here is a sample code demonstrating how to determine if an item in a ListBox is selected.

// 假设ListBox的名称为listBox1

// 判断ListBox中的项是否被选中
if (listBox1.SelectedIndex != -1)
{
    // 有项被选中
    Console.WriteLine("选中的项为：" + listBox1.SelectedItem.ToString());
}
else
{
    // 没有项被选中
    Console.WriteLine("没有选中的项");
}

// 判断特定索引的项是否被选中
int index = 0; // 假设判断第一个项是否被选中
if (listBox1.GetSelected(index))
{
    Console.WriteLine("第一个项被选中");
}
else
{
    Console.WriteLine("第一个项没有被选中");
}

Please note that the console output in the above code can be adjusted according to the actual situation.