1.8. A Simple Java Program | Introduction to Java Programming-Comprehensive Version (6th Edition)

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1.7. The Java Language Specification, API, JDK, and IDE

Computer languages have strict rules of usage. If you do not follow the rules when writing a program, the computer will be unable to understand it. Sun Microsystems, the originator of Java, intends to retain control of this important new computer language ”and for a very good reason: to prevent it from losing its unified standards. The Java language specification and Java API define the Java standard.

The Java language specification is a technical definition of the language that includes the syntax and semantics of the Java programming language. The complete Java language specification can be found at java.sun.com/docs/books/jls.

The application program interface ( API ) contains predefined classes and interfaces for developing Java programs. The Java language specification is stable, but the API is still expanding. At the Sun Java website (java.sun.com), you can view and download the latest version of the Java API.

Java was introduced in 1995. Sun announced the Java 2 platform in December 1998. Java 2 is the overarching brand that applies to current Java technology. There are three editions of the Java API: Java 2 Standard Edition (J2SE) , Java 2 Enterprise Edition (J2EE) , and Java 2 Micro Edition (J2ME) . Java is a full-fledged and powerful language that can be used in many ways. J2SE can be used to develop client-side standalone applications or applets. J2EE can be used to develop server-side applications, such as Java servlets and JavaServer Pages. J2ME can be used to develop applications for mobile devices, such as cell phones. This book uses J2SE to introduce Java programming.

There are many versions of J2SE. The latest version is J2SE 5.0, which will be used in this book. Sun releases each version of J2SE with a Java Development Toolkit (JDK) . For J2SE 5.0, the Java Development Toolkit is called JDK 5.0. JDK 5.0 was formerly known as JDK 1.5. Since most Java programmers are familiar with the name JDK 1.5, this book uses the names JDK 5.0 and JDK 1.5 interchangeably.

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JDK consists of a set of separate programs for developing and testing Java programs, each of which is invoked from a command line. Besides JDK, there are more than a dozen Java development tools on the market today. Three major development tools are:

JBuilder by Borland (http://www.borland.com/)
NetBeans Open Source by Sun (http://www.netbeans.org/)
Eclipse Open Source by IBM (http://www.eclipse.org/)

Other useful tools are:

Code Warrior by Metrowerks (http://www.metrowerks.com/)
TextPad Editor (http://www.textpad.com/)
JCreator LE (http://www. jcreator .com/)
JEdit (http://www. jedit .org/)
JGrasp (http://www.jgrasp.org/)
BlueJ (http://www.bluej.org/)
DrJava (http:// drjava . sourceforge .net/)

A Java development tool is software that provides an integrated development environment ( IDE ) for rapidly developing Java programs. Editing, compiling, building, debugging, and online help are integrated in one graphical user interface. Just enter source code in one window or open an existing file in a window, then click a button, menu item, or function key to compile and run the program.