Errata

There is an extra "(" in the doGet() method in the first Java code example in the book.

"public void doGet((" should be "public void doGet("

The ending '}' is missing from the expression:
<my:myAction attr="${myFunction(someArg, anotherArg)" />
it should be:
<my:myAction attr="${myFunction(someArg, anotherArg)}" />

The text refers to userinputvalidate.jsp, but the figure calls that file userinfovalidate.jsp.

... represents the Model, the userinputvalidate.jsp page the Controller...
should be:
... represents the Model, the userinfovalidate.jsp page the Controller...

Says "the link URL is left unencoded." Okay, in the concrete example
this is not an issue, because there is only one parameter. But HTML-Tidy
complains about & in links like <a href="example.jsp?a=b&x=y">. It should
be <a href="example.jsp?a=b&amp;x=y"> (see http://www.w3.org/TR/html4/appendix/
notes.html#h-B.2.2). Therefore, in general, I suggest <a href="<c:out
value="${productURL}"/>">.

AUTHOR'S REPLY:

Oops, yes you're right; the URL _should_ use &amp; instead of &.
So, use either <c:out> (as you suggest) or ${fn:escapeXml()} (which
I think is cleaner, especially for code that is used as an HTML attribute).

The discussion of the special tag scope of a tag file neglects to mention that not
only is the scope different from the page scope, but it is also exposed to the tag
file as a different implicit variable. For tag files, the page scope is represented
by the implicit variable jspContext and the pageContext implicit variable is not
defined. See Table JSP.8-5 Implicit Objects Available in Tag Files in the JSP 2.0
specification.

jspContext should also be mentioned in the Implicit Variables section of Appendix D
JSP API Reference

The taglib directive on page 170 has a URI attribute value of "mytags", it should be "mytaglib".

The paragraph text is "At the top of the page is the same JSP directive for using the
JSTL database tag library as in Example 12-1". Example 12-2 in fact does not have
this directive included, nor does it need it since the result was stored in the
session variable "newEmpDbInfo". This paragraph should likely be removed.

The attribute name "pattern" in the <fmt:formatNumber> table (page 253 table 14-10)
seems to have the wrong description.
It looks like the description was copied from the <fmt:formatDate> table
(page 251 table 14-7) by mistake.
The table on page 253 should be the same as the first table on page 586
(the fmt:formatNumber section of appendix B).

<x:param name="empName" value="${param:empName}" />
^
should be:

<x:param name="empName" value="${param.empName}" />

On page 322 at the top of page, the </jsp-property-grop> end element
^^^^
should be:

</jsp-property-group>

The "u" in group is missing. This occurs again on page 323 (twice), page 324
(twice), page 325 (once) and page 326 (twice).

Line 27 getJspContext().setAttribute(var, currValue);
should be
pageContext.setAttribute(var, currValue);
Otherwise, remove PageContext pageContext = (PageContext) getJspContext(); since it accomplishes nothing. Also, it is not clear that the <body-content> must be set to scriptless for this tag to work as described on 429.

the screencapture is wrong.
The cells for March 30 and 31 should have the same shading as the cells for May 1 - 3.

items should be a Collection, not a String

The code line:

_jspx_th_xmp_varProducer_1.setId("myVariable");
^^^^^^^^^^
should be:
_jspx_th_xmp_varProducer_1.setId("someList");

The code cited below that lives in the example at the top of page 541:

String sql = "SELECT * FROM Employee WHERE UserName = ?");
^
should be:
String sql = "SELECT * FROM Employee WHERE UserName = ?";

The sql:query element in example 24-8 seems to have have some extra attribute information

<sql:query var="newEmpDbInfo"="${example}" scope="session">
^^^^^^^^^^^^^
should be:
<sql:query var="newEmpDbInfo" scope="session">

at the end of the 4th line in the last code-block is the %> missing

<% pageContext.setAttribute("scopedVar", headerPage);
should be:
<% pageContext.setAttribute("scopedVar", headerPage); %>

In the examples for functions toLowerCase and toUpperCase param:day should be param.day
The same should be fixed for the startsWith() and trim() examples.

The line that reads:

version="2.4>

should be:

version="2.4">