Getting Ready for JavaWhat is Java?Declarations, statements, and commentsSyntax and semanticsTwo aspects of JavaVersions of JavaVocabulary IVocabulary IIBlueJEleganceWhat You NeedGetting ReadyThe EndGetting Ready for JavaWhat is Java?•Java is a programming language: a language that you can learn to write, and the computer can be made to understand•Java is currently a very popular language•Java is a large, powerful language–but it is not simple!•Compared to C++, Java is elegantDeclarations, statements, and comments•A declaration gives some information to the computer •A statement tells the computer to do something–Statements should really be called “commands”•Comments are ignored by the computer--they are explanations of your program for human beings to readSyntax and semantics•Syntax is the “grammar” of the language–The syntax of Java is large, but finite–Syntax must be absolutely correct–The computer will point out every syntax error–Error messages may be helpful or misleading•Semantics is the “meaning” of your program–Semantic errors cause your answers to be wrong–You may or may not get error messagesTwo aspects of Java•Java has syntax and semantics–This is where you begin–It is possible to learn everything about Java’s syntax and semantics–We will cover most of Java’s syntax and semantics•Java also has “packages”–Packages are sort of like vocabulary bundles–To be good at Java, you need to learn many packages–There are more Java packages than you can ever learnVersions of Java•Java 1–Java 1.0: Original, not very good version–Java 1.1: Greatly revised and improved•Java 2–Java 1.2: Includes “Swing”–Java 1.3: Last year’s best version–Java 1.4: The latest and best versionVocabulary I•JRE, Java Runtime Environment–The software that allows you to run Java programs on your computer•JDK, Java Development Kit; also•SDK, System Development Kit–The software that allows you to create and run Java programs on your computer•IDE, Integrated Development Environment–A tool that makes it easier to write programsVocabulary II•Beta software–Software that is new, untested, often buggy•Interface–the place where things touch each other–the way that distinct things communicate•GUI, Graphical User Interface–A way for the computer and the user to communicate via graphics (pictures) on the screenBlueJ•BlueJ is an IDE (Integrated Development Environment). It includes–an editor, which you use to write your programs–a debugger, to help you find your mistakes–a viewer, to see the parts of your program–an easy way to run Java programs–an easy way to view documentationElegance•Powerful software can do everything you want to do--for example, Microsoft Word•Complex software is hard to learn and hard to use--for example, Microsoft Word•More power usually means more complexity•Elegant software somehow manages to be both powerful and simple•BlueJ is elegantWhat You Need•48 MB of RAM (64 MB recommended)•166 MHz Pentium or better–Macintosh: must run Mac OS X•SDK 1.4 (includes JRE)•BlueJ 1.2–Earlier versions do not fully support Java 1.4•By the way: the SDK and BlueJ are freeGetting Ready•If you plan to use your own computer:–Download and install Java SDK 1.4•http://java.sun.com/j2se/1.4/download.html•Download J2SETM v 1.4.0_02Windows (all languages, including English)--SDK–Download and install BlueJ 1.2•http://www.bluej.o r g/–[Optional] Download the Java documentation•http://java.sun.com/j2se/1.4/download.html•J2SE 1.4 DocumentationThe
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