Getting Ready for Java

1
Getting Ready for Java
2
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

3
Declarations, statements, 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 computerthey are
  explanations of your program for human beings to
  read

4
Syntax 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 messages

5
Two aspects of Java

• Java has syntax and semantics
• This is where you begin
• It is possible to learn everything about Javas
  syntax and semantics
• We will cover most of Javas 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

6
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 More new packages, no new syntax
• Java 1.4 Introduces the assert statement
• Java 5
• Java 1.5 Quite a bit of new syntax

7
Vocabulary I

• JRE, Java Runtime Environment
• This is the software that allows you to run Java
  programs on your computer
• JDK, Java Development Kit (previously called SDK,
  System Development Kit)
• The software that allows you to create and run
  Java programs on your computer
• When you install the SDK, you get a JRE along
  with it
• IDE, Integrated Development Environment
• A tool that makes it easier to write programs

8
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

9
BlueJ

• 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 documentation

10
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
• Unfortunately, its also a bit buggy

11
What You Need

• 128 MB of RAM (256 MB recommended)
• 500 MHz Pentium or better
• Macintosh must run Mac OS X, preferably Panther
  (10.4)
• Java JDK 1.5 (includes JRE)
• BlueJ 2.0.5 or better
• Earlier versions of BlueJ have serious problems
• If you have an older version, update!
• By the way the JDK and BlueJ are free

12
Getting Ready

• If you plan to use your own computer
• Download and install Java JDK 1.5
• http//java.sun.com/j2se/1.5.0/download.jsp
• Download the JDK, not the JRE
• If your computer cant run Java 1.5, get Java
  1.4.2
• Optional, but strongly recommended Download the
  Java 1.5 documentation from the same location
• Download and install BlueJ 2.0.5 or newer
• http//www.bluej.org/

13
The End