Download Getting Ready for Java

Getting Ready for Java
What 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 elegant
Declarations, 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
read
Syntax and semantics
• Syntax is the “grammar” of the language
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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 messages
Two 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 learn
Versions 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 version
Vocabulary 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 programs
Vocabulary 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 screen
BlueJ
• BlueJ is an IDE (Integrated Development
Environment). It includes
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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 documentation
Elegance
• 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 elegant
What 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 free
Getting 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_02
Windows (all languages, including English)--SDK
– Download and install BlueJ 1.2
• http://www.bluej.org/
– [Optional] Download the Java documentation
• http://java.sun.com/j2se/1.4/download.html
• J2SE 1.4 Documentation
The End