Tuesday, January 22, 2002

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CM245 Lecture 1
CM245 Contemporary Programming Methods
Tuesday, January 22, 2002 Cecil P.
Schmidt Department of Computer Information
Sciences Washburn University Topeka, KS.
66621 zzschmid_at_washburn.edu
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Presentation Outline

• Syllabus
• Introduction to Java
• Chapter 1 of Bell Parr
• How to compile a Java program at Washburn
• Punch and run assignment

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Introduction 1

• About the text book
• How to write Java programs
• How to run Java programs as free-standing
  programs
• How to invoke a Java program from a World-Wide
  Web browser
• Its for beginners
• Start with visual aspects to elicit interests

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Introduction 2

• Why Java
• Small and beautiful Lean design ultimately
  powerful
• Its object-oriented from the ground up
• Supports the internet and networking in general
• Its general purpose
• Platform-independent (run anywhere)
• Robust (protected against viruses)
• Lots of class libraries http//java.sun.com/produc
  ts/jdk/1.2/docs/index.html
• History of Java
• Originally called Oak but had to be renamed
  because there was already a language named Oak
• John Gosling of Sun Microsystems was the
  principal designer
• Arose from need to construct software for
  consumer electronics

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Introduction 3

• Overview of book
• Covers fundamentals of programming
• Variables assignment input and output
  calculations graphics and windows repetition
  selection
• Classes
• Objects
• Methods
• Using library classes
• Advanced aspects such as inheritance and
  polymorphism
• Applets and the World Wide Web
• Approach is more towards applets but we will be
  doing standalone programs as well so that we can
  improve our debugging capabilities
• GUIs (Graphical User Interface) components such
  as windows, buttons, scrollbars, and using the
  mouse will be included
• What version of Java?
• 1.1 or higher is required
• java version at the command line will tell you
  what the version is.

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Chapter 1 The scope of Java

• How did java come to be?
• The Internet and the Web
• Internet the world-wide collection of computers
  connected by a network of communication channels
• Universal infrastructure
• Single UI (user interface)
• Single client - the Web browser
• Single network protocol - HTTP
• Single server - web server
• This Network allows us to communicate
• Email and web sites
• Web sites
• essentially a file on disk that is connected to
  the internet
• these files can be static or dynamic
• access to a web site is called a site visit"

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The World-Wide Web

• The collection of sites across the world is
  called the"World-Wide Web or WWW
• Typical sites include (these are called a site
  address)
• http//www.microsoft.com
• http//www.washburn.edu
• URL universal resource locator
• Browser allows you read and execute web pages
• Internet Explorer
• Netscape

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Hypertext

• HTML
• hypertext markup language
• Used to create web pages which can initiate
  static or dynamic content
• Example of a web page with dynamic content
• lthtmlgt ltheadgt
• lttitlegt Web page with Applet lt/titlegt lt/headgt
• ltbodygt
• ltapplet code"Hello.class
• width300 height200gt lt/appletgt
• lt/bodygt
• lt/htmlgt

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Applets

• To execute a program with a java applet the
  browser MUST be java enabled (remember!)
• The java program actually runs local on the
  client
• Other programs actually run on the web server.
• Servlets Java programs that execute at the web
  server
• CGI A program written in any language which runs
  at the server. Typically these are in PERL, PSP,
  C, etc.
• These do not have to be supported with a Java
  enabled browser.
• IE 4.0 and Netscape 4.0 (and higher are all Java
  enabled)

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What is a Program?

• A program is a list of instructions that can be
  obeyed automatically by a computer which are
  used to complete a task.
• Program examples include
• Loan calculations programs
• Check books
• Chess
• Microsoft Word

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Object Oriented Programming

• OOP
• Allows us to represent components of a program as
  interacting objects or modules.
• Class represents the structure of an object
• cookie cutter
• object factory
• Inheritance a classification scheme
• Superclass
• Subclass

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How to compile a Java program at Washburn?

• How do I edit a program
• vi (text based)
• Nedit (my suggestion)
• Pico (text based, but easier to learn than vi)
• What are the steps to compile and run a java
  program?
• javac ltfilename.javagt
• java ltfilenamegt