帮我看看出错原因？

/en/time4.jsp:10: ')' expected
Timestamp A = Timestamp.valueOf(String sb);
^
1 error
源码:
<%@ page import = "java.util.*" %>
<%@ page import = "java.text.*" %>
<%@ page import = "java.sql.*" %>
<%
SimpleDateFormat sdf = new SimpleDateFormat("yyyy.MM.dd ' ' HH:mm:ss ");
Date currentTime = new Date();
String sb = sdf.format(currentTime);
//session.setAttribute("inforCurtime",sb);
out.println(sb);
Timestamp A = Timestamp.valueOf(String sb);

out.println(A);
%>