Checking for a not null, not blank String in Java

Question

I am trying to check if a Java String is not null, not empty and not whitespace.

In my mind, this code should have been quite up for the job.

Answer 1

<% 
System.out.println(request.getParameter("userName")+"*");

if (request.getParameter("userName").trim().length() == 0 | request.getParameter("userName") == null) { %>

<% }
 else { %>
Hello ${param.userName}
<%} %>