Introduction - Java Software Solutions: Foundations of Program Design - page 41

errors in a program. Other tools that may be included are documentation genera-
tors, archiving tools, and tools that help you visualize your program structure.
Included in the download of the Java Standard Edition is the Java

Software
Development Kit (SDK), which is sometimes referred to simply as the Java
Development Kit (JDK). The Java SDK contains the core development tools
needed to get a Java program up and running, but it is not an integrated envi-
ronment. The commands for compilation and interpretation are executed on the
command line. That is, the SDK does not have a GUI. It also does not include an
editor, although any editor that can save a document as simple text can be used.
One of the most popular Java IDEs is called Eclipse (see www.eclipse.org) .
Eclipse is an open source project, meaning that it is developed by a wide collection
of programmers and is available for free. Other popular Java IDEs include jEdit
( www.jedit.org ), DrJava (drjava.sourceforge.net), jGRASP ( www.jgrasp.com) , and
BlueJ ( www.bluej.org ).
Various other Java development environments are available. A
Web search will unveil dozens of them. The choice of which devel-
opment environment to use is important. The more you know about
the capabilities of your environment, the more productive you can
be during program development.

VideoNote

Comparison of Java
IDEs.

KEY CONCEPT
Many different development environ-
ments exist to help you create and
modify Java programs.

Syntax and Semantics
Each programming language has its own unique syntax. The syntax rules of a

language dictate exactly how the vocabulary elements of the language can be
combined to form statements. These rules must be followed in order to create a
program. We've already discussed several Java syntax rules. For instance, the fact
that an identifier cannot begin with a digit is a syntax rule. The fact that braces
are used to begin and end classes and methods is also a syntax rule. Appendix L
formally defines the basic syntax rules for the Java programming language, and
specific rules are highlighted throughout the text.
During compilation, all syntax rules are checked. If a program is not syntacti-
cally correct, the compiler will issue error messages and will not produce byte-
code. Java has a similar syntax to the programming languages C and C++, and
therefore the look and feel of the code is familiar to people with a background in
those languages.
The semantics of a statement in a programming language define what will
happen when that statement is executed. Programming languages are generally
unambiguous, which means the semantics of a program are well defined. That is,
there is one and only one interpretation for each statement. On the other hand,
the natural languages that humans use to communicate, such as English and