获取列表框的选定索引（C＃）

Question

I have a ListBox with SelectionMode set to multiple. When I check the selected index using ListBox1.SelectedIndex I always get -1 even if I click on a item?? I would like to be able to get index of multiple selected items in the listbox.

Answer 1

使用GetSelectedIndices()方法。

Answer 2

Since there can be more than one item selected you have to get the collection of SelectedItems. Loop through them. Each item has Index property.

Answer 3

Try this method

ListBox.SelectedIndexCollection SelectedIndices { get; }

SelectedIndex method is used when you allow to select only one value.

Answer 4

Try something like this. You will get all selected indexes in one string with this code.

int length = this.ListBox1.Items.Count;
    StringBuilder b = new StringBuilder();
    for ( int i = 0 ; i < length; i++ )
         {
      if ( this.ListBox1.Items[ i ] != null && this.ListBox1.Items[ i ].Selected ) 
              {
        b.Append( this.ListBox1.Items[ i ].Selected );
        b.Append( "," );
          }
     }
    if ( b.Length > 0 ) 
        {
      b.Length = b.Length - 1;
    }
    return b.ToString();