c# - How do i make that it will register to the click event but won't add the items more then once in the richTextbox mouseenter? -

toolstripmenuitem s;         private void recentfilestoolstripmenuitem_mouseenter(object sender, eventargs e)         {             if (lines != null)             {                 (int = 0; < lines.length; i++)                 {                     s = new toolstripmenuitem(lines[i]);                     if (!recentfilestoolstripmenuitem.dropdownitems                         .cast<toolstripmenuitem>()                         .any(x => x.text == lines[i]))                     {                         recentfilestoolstripmenuitem.dropdownitems.add(s);                         s.click += s_click;                     }                 }             }         } 

it's never pass if checking.

i need check if items(lines) exist in recentfilestoolstripmenuitem.dropdownitems not add them more once each time i'm enetering mouse. , register s.click once i'm clicking on item.

edit form1 constructor read text file recentfiles.txt , add lines items dropdownitems:

recentfiles = @"e:\recentfiles.txt";             if (!file.exists(recentfiles))             {                 recentfiles = new streamwriter(recentfiles);                 recentfiles.close();             }             else             {                 lines = file.readalllines(recentfiles);                 items = file                         .readlines(recentfiles)                         .select(line => new toolstripmenuitem()                         {                           text = line                         })                         .toarray();                  using (streamwriter writer = new streamwriter(recentfiles))                 {                     (int = 0; < lines.length; i++)                     {                         if (file.exists(lines[i]))                         {                             writer.writeline(lines[i]);                             {                                 text = lines[i];                             }                         }                     }                 }                 lines = file.readalllines(recentfiles);                 items = file                         .readlines(recentfiles)                         .select(line => new toolstripmenuitem()                         {                             text = line                         })                         .toarray();                 recentfilestoolstripmenuitem.dropdownitems.addrange(items);              } 

the content of recentfiles.txt is:

d:\test.txt d:\test1.txt