Changes in the Fifth Edition
The fifth edition of this book covers Java 5.0. As its incremented
version number attests, this new version of Java has a lot of new
features. The three most significant new language features are
generic types, enumerated types, and annotations, which are covered
in a new chapter of their own. Experienced Java programmers who just
want to learn about these new features can jump straight to Chapter 4.Other new language features of Java 5.0 are:- The for/in statement for easily iterating
through arrays and collections (this statement is sometimes called
"foreach"). - Autoboxing and autounboxing
conversions to automatically convert back and forth between primitive
values and their corresponding wrapper objects (such as
int values and Integer objects)
as needed.
Varargs methods to define and invoke methods
that accept an arbitrary number of arguments.- Covariant
returns to allow a subclass to override a superclass method and
narrow the return type of the method. - The import static declaration to import the
static members of a type into the namespace.
Although each of these features is new in Java 5.0, none of them is
large enough to merit a chapter of its own. Coverage of these
features is integrated into Chapter 2.In addition to these language changes, Java 5.0 also includes changes to the
Java platform. Important enhancements include the following:- The java.util collections classes have been converted
to be generic types, providing support for typesafe collections. This
is covered in Chapter 4. - The java.util
package
also includes the new Formatter class. This class
enables C-style formatted text output with printf(
)
and format( )
methods. Examples are included in Chapter 5.
The java.util.Formatter enTRy in the quick
reference includes a detailed table of formatting options. - The new package
java.util.concurrent
includes important
utilities for threadsafe concurrent programming. Chapter 5 provides examples. - java.lang has three new subpackages:
- java.lang.annotation
- java.lang.instrument
- java.lang.management
- These packages support Java 5.0
annotations and the instrumentation,
management, and monitoring of a running Java interpreter. Although
their position in the java.lang hierarchy marks
these packages as very important, they are not commonly used.
Annotation examples are provided in Chapter 4,
and a simple instrumentation and management example is found in Chapter 5. - New packages have been added to the
javax.xml
hierarchy.
javax.xml.validation supports document validation with
schemas. javax.xml.xpath supports the
XPath query language.
And javax.xml.namespace provides simple support
for XML
namespaces.
Validation and XPath examples are in Chapter 5.
In a mostly futile attempt to make room for this new material,
I've had to make some cuts. I've
removed coverage of the packages java.beans,
java.beans.beancontext,
java.security.acl, and
org.ietf.jgss from the quick reference.
JavaBeans
standards have not caught on in core Java APIs and now appear to be
relevant only for Swing and related graphical APIs. As such, they are
no longer relevant in this book. The
java.security.acl package has been deprecated
since Java 1.2 and I've taken this opportunity to
remove it. And the org.ietf.jgss package is of
interest to only a very narrow subset of readers.Along with removing coverage of java.beans from
the quick reference section, I've also cut the
chapter on JavaBeans from Part I of this book. The material on
JavaBeans naming conventions from that chapter remains useful,
however, and has been moved into Chapter 7. |
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