Add dropdown menus with a little extra HTML and the dropdowns JavaScript plugin.
<!DOCTYPE HTML>
<html>
<head>
<link href="http://java2s.com/style/bootstrap.min.css" rel="stylesheet">
<!--from w ww .j a v a 2 s .c o m-->
<script src="http://java2s.com/style/jquery-1.8.0.min.js"></script>
<script src="http://java2s.com/style/bootstrap.min.js"></script>
</head>
<body style='margin: 20px;'>
<ul class="nav nav-tabs">
<li class="active"><a href="#">Home</a></li>
<li><a href="#">Help</a></li>
<li class="dropdown"><a class="dropdown-toggle"
data-toggle="dropdown" href="#"> Dropdown <span class="caret"></span>
</a>
<ul class="dropdown-menu">
<li><a href="#">Action</a></li>
<li><a href="#">Another action</a></li>
<li><a href="#">Something else here</a></li>
<li class="divider"></li>
<li><a href="#">Separated link</a></li>
</ul></li>
</ul>
</body>
</html>