毕业设计说明书
英文文献及中文翻译
指导教师：
2014 年 6 月
引导近义词An Introduction to Java
The first relea of Java in 1996 generated an incredible amount of excitement, not just in the computer press, but in mainstream media such as The New York Times, The Washington Post, and Business Week. Java has the distinction of being the first and only programming language that had a ten-minute story on National Public Radio. A $100,000,000 venture capital fund was t up solely for products produced by u of a specific computer language. It is rather amusing to revisit tho heady times, and we give you a brief history of Java in this chapter.
In the first edition of this book, we had this to write about Java: “As a computer language, Java’s hype is overdone: Java is certainly a good program-ming language. There is no do
ubt that it is one of the better languages available to rious programmers. We think it could potentially have been a great programming language, but it is probably too late for that. Once a language is out in the field, the ugly reality of compatibility with existing code ts in.”
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Our editor got a lot of flack for this paragraph from someone very high up at Sun Micro- systems who shall remain unnamed. But, in hindsight, our prognosis ems accurate. Java has a lot of nice language features—we examine them in detail later in this chapter. It has its share of warts, and newer additions to the language are not as elegant as the original ones becau of the ugly reality of compatibility.
But, as we already said in the first edition, Java was never just a language. There are lots of programming languages out there, and few of them make much of a splash. Java is a whole platform, with a huge library, containing lots of reusable code, and an execution environment that provides rvices such as curity, portability across operating sys-tems, and automatic garbage collection.
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房地产销售说辞As a programmer, you will want a language with a pleasant syntax and comprehensible mantics (i.e., not C++). Java fits the bill, as do dozens of other fine languages. Some languages give you portability, garbage collection, and the like, but they don’t have much of a library, forcing you to roll your own if you want fancy graphics or network- ing or databa access. Well, Java has everything—a good language, a high-quality exe- cution environment, and a vast library. That combination is what makes Java an irresistible proposition to so many programmers.
Simple
We wanted to build a system that could be programmed easily without a lot of eso- teric training and which leveraged today’s standard practice. So even though we found that C++ was unsuitable, we designed Java as cloly to C++ as possible in order to make the system more comprehensible. Java omits many rarely ud, poorly understood, confusing features of C++ that, in our experience, bring more grief than benefit. 防火征文
The syntax for Java is, indeed, a cleaned-up version of the syntax for C++. There is no need for header files, pointer arithmetic (or even a pointer syntax), structures, unions, operator overloading, virtual ba class, and so on. (See the C++ notes intersperd throughout the text for more on the differences between Java and C++.) The designers did not, however, attempt to fix all of the clumsy features of C++. For example, the syn- tax of the switch statement is unchanged in Java. If you know C++, you will find the tran- sition to the Java syntax easy. If you are ud to a visual programming environment (such as Visual Basic), you will not find Java simple. There is much strange syntax (though it does not take long to get the hang of it). More important, you must do a lot more programming in Java. The beauty of Visual Basic is that its visual design environment almost automatically pro- vides a lot of the infrastructure for an application. The equivalent functionality must be programmed manually, usually with a fair bit of code, in Java. There are, however, third-party development environments that provide “drag-and-drop”-style program development.
Another aspect of being simple is being small. One of the goals of Java is to enable the construction of software that can run stand-alone in small machines. The size of the basic interpreter and class support is about 40K bytes; adding the basic stan- dard libraries and thread support (esntially a lf-contained microkernel) adds an additional 175K.
This was a great achievement at the time. Of cour, the library has since grown to huge proportions. There is now a parate Java Micro Edition with a smaller library, suitable for embedded devices.
Object Oriented
Simply stated, object-oriented design is a technique for programming that focus on the data (= objects) and on the interfaces to that object. To make an analogy with carpentry, an “object-oriented” carpenter would be mostly concerned with the chair he was building, and condarily with the tools ud to make it; a “non-object- oriented” carpenter would think primarily of his tools. The object-ori
ented facilities of Java are esntially tho of C++.
