The following code shows how to create nested button groups.
<!DOCTYPE html>
<html>
<head>
<script type='text/javascript'
src='http://code.jquery.com/jquery-git2.js'></script>
<link rel="stylesheet" type="text/css"
href="http://getbootstrap.com/assets/css/docs.css">
<link rel="stylesheet" type="text/css"
href="http://netdna.bootstrapcdn.com/bootstrap/3.0.0-rc1/css/bootstrap.min.css">
<script type='text/javascript'
src="http://netdna.bootstrapcdn.com/bootstrap/3.0.0-rc1/js/bootstrap.min.js"></script>
</head><!--from w w w .j a v a 2 s . com-->
<body style='margin:30px'>
<h3 id="btn-groups-nested">Nested button groups</h3>
<div class="btn-group">
<button type="button" class="btn btn-default">1</button>
<button type="button" class="btn btn-default">2</button>
<div class="btn-group">
<button type="button" class="btn btn-success dropdown-toggle"
data-toggle="dropdown">
Dropdown <span class="caret"></span>
</button>
<ul class="dropdown-menu">
<li><a href="#">Dropdown link</a></li>
<li><a href="#">Dropdown link</a></li>
</ul>
</div>
</div>
</body>
</html>