問54
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Java 言語に関する記述として, 適切なものはどれか。
平成22年度 秋期 ITパスポート試験 問54
テクノロジ系アルゴリズムとプログラミング › プログラム言語
This question's explanation and your answers so far.
解説
問 54
Incorrectア
The markup language for describing Web pages is HTML (HyperText Markup Language), not Java. A markup language embeds marks called tags in a document to specify the meaning and appearance of each part, such as headings, paragraphs, tables, and links; its role differs from that of a programming language, which describes processing steps such as calculations and conditional branches. Java is also a different thing from the similarly named JavaScript (a scripting language that adds behavior to Web pages), so be careful not to confuse them.
Incorrectイ
The language developed for scientific and technical computation is FORTRAN. FORTRAN has notation that lets you write mathematical formulas almost as they are, along with rich numerical computation features, and it has long been used for numerical computation in physics and engineering. Java was not created to specialize in a particular computational field; it is a general-purpose object-oriented language, so this description does not apply.
- ウ
正解 The correct answer is ウ: it is an object-oriented language that can develop software independent of the computer model or OS. Java's features come down to these two points. First, Java is an object-oriented programming language in which a program is built by combining objects, each of which bundles data together with the procedures that operate on it. Second, Java source code is not translated directly into machine language for a specific computer model; it is converted into bytecode, an intermediate form that is the same in every environment. This bytecode is then interpreted and run by the Java Virtual Machine (JVM) on the computer where you want to execute it. Because of this, the virtual machine absorbs the differences between models and operating systems, so the same program runs as it is on Windows, on UNIX-like systems, or on embedded devices. This property is called write once, run anywhere, and the statement that software independent of the model or OS can be developed refers to exactly this. Java applets, which run in a Web browser, and Java servlets, which run on the server side, have been used across many environments thanks to this high portability.
Incorrectエ
The language developed for business data processing computation is COBOL. COBOL uses a writing style close to English sentences and has features suited to handling reports and large volumes of business data (files), and it has long been used in the core business systems of financial institutions and companies. Java is not a language designed specifically for business data processing, so this description does not apply either.
ここがポイント
- Remember Java's two main features: (1) it is an object-oriented programming language, and (2) it converts source code into bytecode, an intermediate form common to all computer models, which the Java Virtual Machine (JVM) in each environment then executes, so software independent of the model or OS can be developed. Whenever a choice lists both independence from the model or OS and object orientation, you can judge that it refers to Java.
- Memorize the typical programming languages and what each is used for: HTML is a markup language for describing Web pages (not a programming language), FORTRAN is for scientific and technical computation, COBOL is for business data processing computation, C is for writing systems, and Java is object-oriented and independent of the computer model. Also keep in mind that Java and JavaScript merely have similar names and are different languages, a trap that appears often in exams.
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