Common Misconceptions about Java Core Java

We close this chapter with a list of some common misconceptions about Java, along with commentary.

Java is an extension of HTML.

Java is a programming language; HTML is a way to describe the structure of a web page. They have nothing in common except that there are HTML extensions for placing Java applets on a web page.

I use XML, so I don’t need Java.

Java is a programming language; XML is a way to describe data. You can process XMLdata with any programming language, but the Java APIcontains excellent support for XML processing. In addition, many important third-party XML tools are implemented in Java.

Java is an easy programming language to learn.

No programming language as powerful as Java is easy. You always have to distinguish between how easy it is to write toy programs and how hard it is to do serious work.

Java will become a universal programming language for all platforms.

This is possible, in theory, and it is certainly the case that every vendor but Microsoft seems to want this to happen. However, many applications, already working perfectly well on desktops, would not work well on other devices or inside a browser. Also, these applications have been written to take advantage of the speed of the processor and the native user interface library and have been ported to all the important platforms anyway. Among these kinds of applications are word processors, photo editors, and web browsers. They are typically written in C or C++, and we see no benefit to the end user in rewriting them in Java.

Java is just another programming language.

Java is a nice programming language; most programmers prefer it over C, C++, or C#. But there have been hundreds of nice programming languages that never gained widespreadpopularity, whereas languages with obvious flaws, such as C++ and VisualBasic, have been wildly successful.

Why? The success of a programming language is determined far more by the utility of the support system surrounding it than by the elegance of its syntax. Are there useful, convenient, and standard libraries for the features that you need to implement? Are there tool vendors that build great programming and debugging environments? Doesthe language and the toolset integrate with the rest of the computing infrastructure? Java is successful because its class libraries let you easily do things that were hard before, such as networking and multithreading. The fact that Java reduces pointer errors is a bonus and so programmers seem to be more productive with Java, but these factors are not the source of its success.

Now that C# is available, Java is obsolete.

C# took many good ideas from Java, such as a clean programming language, a virtual machine, and garbage collection. But for whatever reasons, C# also left some good stuff behind, in particular security and platform independence. If you are tied to Windows, C# makes a lot of sense. But judging by the job ads, Java is still the language of choice for a majority of developers.

Java is proprietary, and it should therefore be avoided.

Sun Microsystems licenses Java to distributors and end users. Although Sun has ultimate control over Java through the “Java Community Process,” they have involved many other companies in the development of language revisions and the design of newlibraries. Source code for the virtual machine and the libraries has always been freelyavailable, but only for inspection, not for modification and redistribution. Up to this point, Java has been “closed source, but playing nice.”

This situation changed dramatically in 2007, when Sun announced that future versions of Java will be available under the General Public License, the same open source license that is used by Linux. It remains to be seen how Sun will manage the governance of Java in the future, but there is no question that the open sourcing of Java has been a very courageous move that will extend the life of Java by many years.

Java is interpreted, so it is too slow for serious applications.

In the early days of Java, the language was interpreted. Nowadays, except on “micro” platforms such as cell phones, the Java virtual machine uses a just -in -time compiler. The “hot spots” of your code will run just as fast in Java as they would in C++, and in somecases, they will run faster.

Java does have some additional overhead over C++. Virtual machine startup time is slow, and Java GUIs are slower than their native counterparts because they are painted in a platform-independent manner.

People have complained for years that Java applications are too slow. However, today’s computers are much faster than they were when these complaints started. A slow Java program will still run quite a bit better than those blazingly fast C++ programs did a few years ago. At this point, these complaints sound like sour grapes, and some detractors have instead started to complain that Java user interfaces are ugly rather than slow.

All Java programs run inside a web page.

All Java applets run inside a web browser. That is the definition of an applet—a Java program running inside a browser. But most Java programs are stand-alone applications that run outside of a web browser. In fact, many Java programs run on web servers and produce the code for web pages.

Most of the programs here are stand-alone programs. Sure, applets can be fun. But stand-alone Java programs are more important and more useful in practice.

Java programs are a major security risk.

In the early days of Java, there were some well -publicized reports of failures in the Java security system. Most failures were in the implementation of Java in a specific browser. Researchers viewed it as a challenge to try to find chinks in the Java armor and to defy the strength and sophistication of the applet security model. The technical failures that they found have all been quickly corrected, and to our knowledge, no actual systems were ever compromised. To keep this in perspective, consider the literally millions of virus attacks in Windows executable files and Word macros that cause real grief but surprisingly little criticism of the weaknesses of the attacked platform. Also, the ActiveX mechanism in Internet Explorer would be a fertile ground for abuse, but it is so boringly obvious how to circumvent it that few researchers have bothered to publicize their findings.

Some system administrators have even deactivated Java in company browsers, while continuing to permit their users to download executable files, ActiveX controls, and Word documents. That is pretty ridiculous—currently, the risk of being attacked by hostile Java applets is perhaps comparable to the risk of dying from a plane crash; the risk of being infected by opening Word documents is comparable to the risk of dying while crossing a busy freeway on foot.

JavaScript is a simpler version of Java.

JavaScript, a scripting language that can be used inside web pages, was invented by Netscape and originally called LiveScript. JavaScript has a syntax that is reminiscent of Java, but otherwise there are no relationships (except for the name, of course). A subset of JavaScript is standardized as ECMA-262. JavaScript is more tightly integrated with browsers than Java applets are. In particular, a JavaScript program can modify the document that is being displayed, whereas an applet can only control the appearance of a limited area.

With Java, I can replace my computer with a $500 “Internet appliance.”

When Java was first released, some people bet big that this was going to happen. Ever since the first edition of this book, we have believed it is absurd to think that home users are going to give up a powerful and convenient desktop for a limited machine with nolocal storage. We found the Java-powered network computer a plausible option for a“zero administration initiative” to cut the costs of computer ownership in a business, but even that has not happened in a big way.

On the other hand, Java has become widely distributed on cell phones. We must confess that we haven’t yet seen a must-have Java application running on cell phones, but the usual fare of games and screen savers seems to be selling well in many markets.

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