Learning Java, 4th Edition

Enter Java

The Java programming language, developed at Sun Microsystems under the guidance of Net luminaries James Gosling and Bill Joy, was designed to be a machine-independent programming language that is both safe enough to traverse networks and powerful enough to replace native executable code. Java addresses the issues raised here and played a starring role in the growth of the Internet, leading to where we are today.

Initially, most of the enthusiasm for Java centered on its capabilities for building embedded applications for the Web called applets. But in the early days, applets and other client-side GUI applications written in Java were limited. Today, Java has Swing, one of the most sophisticated toolkits for building graphical user interfaces (GUIs) in any language. This development has allowed Java to become a popular platform for developing traditional client-side application software.

Of even more importance, however, Java has become the premier platform for web-based applications and web services. These applications use technologies including the Java Servlet API, Java web services, and many popular open source and commercial Java application servers and frameworks. Java’s portability and speed make it the platform of choice for modern business applications. Java servers running on open source Linux platforms are at the heart of the business and financial world today.

This book will show you how to use Java to accomplish real-world programming tasks. In the coming chapters we’ll cover everything from text processing to networking, building rich client-side GUI applications with Swing and lightweight web-based applications and services.

Java’s Origins

The seeds of Java were planted in 1990 by Sun Microsystems patriarch and chief researcher Bill Joy. At the time, Sun was competing in a relatively small workstation market while Microsoft was beginning its domination of the more mainstream, Intel-based PC world. When Sun missed the boat on the PC revolution, Joy retreated to Aspen, Colorado, to work on advanced research. He was committed to the idea of accomplishing complex tasks with simple software and founded the aptly named Sun Aspen Smallworks.

Of the original members of the small team of programmers assembled in Aspen, James Gosling will be remembered as the father of Java. Gosling first made a name for himself in the early 80s as the author of Gosling Emacs, the first version of the popular Emacs editor that was written in C and ran under Unix. Gosling Emacs became popular but was soon eclipsed by a free version, GNU Emacs, written by Emacs’s original designer. By that time, Gosling had moved on to design Sun’s NeWS, which briefly contended with the X Window System for control of the Unix GUI desktop in 1987. Although some people would argue that NeWS was superior to X, NeWS lost because Sun kept it proprietary and didn’t publish source code while the primary developers of X formed the X Consortium and took the opposite approach.

Designing NeWS taught Gosling the power of integrating an expressive language with a network-aware windowing GUI. It also taught Sun that the Internet programming community will ultimately refuse to accept proprietary standards, no matter how good they may be. The seeds of Java’s licensing scheme and open (if not quite “open source”) code were sown by NeWS’s failure. Gosling brought what he had learned to Bill Joy’s nascent Aspen project. In 1992, work on the project led to the founding of the Sun subsidiary FirstPerson, Inc. Its mission was to lead Sun into the world of consumer electronics.

The FirstPerson team worked on developing software for information appliances, such as cellular phones and personal digital assistants (PDAs). The goal was to enable the transfer of information and real-time applications over cheap infrared and traditional packet-based networks. Memory and bandwidth limitations dictated small, efficient code. The nature of the applications also demanded they be safe and robust. Gosling and his teammates began programming in C++, but they soon found themselves confounded by a language that was too complex, unwieldy, and insecure for the task. They decided to start from scratch, and Gosling began working on something he dubbed “C++ minus minus.”

With the foundering of the Apple Newton (Apple’s earliest handheld computer), it became apparent that the PDA’s ship had not yet come in, so Sun shifted FirstPerson’s efforts to interactive TV (ITV). The programming language of choice for ITV set-top boxes was to be the near ancestor of Java, a language called Oak. Even with its elegance and ability to provide safe interactivity, Oak could not salvage the lost cause of ITV at that time. Customers didn’t want it, and Sun soon abandoned the concept.

At that time, Joy and Gosling got together to decide on a new strategy for their innovative language. It was 1993, and the explosion of interest in the Web presented a new opportunity. Oak was small, safe, architecture-independent, and object-oriented. As it happens, these are also some of the requirements for a universal, Internet-savvy programming language. Sun quickly changed focus, and, with a little retooling, Oak became Java.

Growing Up

It would not be overstating it to say that Java caught on like wildfire. Even before its first official release when Java was still a nonproduct, nearly every major industry player had jumped on the Java bandwagon. Java licensees included Microsoft, Intel, IBM, and virtually all major hardware and software vendors. However, even with all this support Java took a lot of knocks and experienced some growing pains during its first few years.

A series of breach of contract and antitrust lawsuits between Sun and Microsoft over the distribution of Java and its use in Internet Explorer hampered its deployment on the world’s most common desktop operating system—Windows. Microsoft’s involvement with Java also become one focus of a larger federal lawsuit over serious anticompetitive practices at the company, with court testimony revealing concerted efforts by the software giant to undermine Java by introducing incompatibilities in its version of the language. Meanwhile, Microsoft introduced its own Java-derived language called C# (C-sharp) as part of its .NET initiative and dropped Java from inclusion in Windows. C# has gone on to become a very good language in its own right, enjoying more innovation in recent years than has Java.

But Java continues to spread on a wide variety of platforms. As we begin looking at the Java architecture, you’ll see that much of what is exciting about Java comes from the self-contained, virtual machine environment in which Java applications run. Java was carefully designed so that this supporting architecture can be implemented either in software, for existing computer platforms, or in customized hardware. Hardware implementations of Java are used in some smart cards and other embedded systems. You can even buy “wearable” devices, such as rings and dog tags, that have Java interpreters embedded in them. Software implementations of Java are available for all modern computer platforms down to portable computing devices. Today, an offshoot of the Java platform is the basis for Google’s Android operating system that powers billions of phones and other mobile devices.

In 2010, Oracle corporation bought Sun Microsystems and became the steward of the Java language. In a somewhat rocky start to its tenure, Oracle sued Google over its use of the Java language in Android and lost. In July of 2011, Oracle released Java SE 7, a significant Java release.