Java A very Hot ObjectOriented Language

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Java -- A very Hot Object-Oriented Language
Instructors Fu-Chiung Cheng (???) Associate
Professor Computer Science Engineering Tatung
Institute of Technology
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Outline

• Why Java is HOT?
• What is Java?
• What is New? (Java vs C/C)

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Why Java is HOT?

• Write Once, Run Anywhere model.
• Network-Centric Computing (internet programming)
• Interactive Content and Animation
  (multithreading)
• support APIs for both client server
  applications
• Near guarantee that you cant run a bad program.
• WWW Java gives the world a new way to think.

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What is Java?

• Simple (compared to C)
• Ture object-Orentied programming
• Distributed
• Robust
• Secure
• Archetectural Neutral
• Multithreaded

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What is New?

• No global variables -- package.class.field
• No preprocessor -- import statement
• Unicode
• No pointers
• Garbage Collection
• Array and String are first class objects
• No goto statement
• Single Inheritance
• Java documentation generator
• Applet with Web browsers

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What is New?

• Java documentation
• Rich Libraries
• A. 2D, 3D programming model
• B. 2D animation API for video game
• C. API for time-critical audio, vidio and MIDI
  data
• D. Multithreading
• E. Networking
• F. Security
• G. Exception handling
• .

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What is New?

• C/C Compilation, linking loading

linker Loader
Binary File
Compiler
MAC
MAC
MAC
C Program
PC
PC
PC
Sun
Sun
Sun
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What is New?

• Java Compilation, linking, loading verifying
  JVM

Interpreter JVM
Compiler
MAC
MAC
Java Program
Java ByteCode
PC
PC
Sun
Sun
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How Java Works?
Java Program
H A R D W A R E
Loader
Java Compiler
Verifier
Network or File System
Java ByteCode
JVM
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Java Programs

• Java standalone applications
• Fully access your system resources (e.g.
  read/write files).
• Java applets
• No read/write access
• Can not standalone,
• Need browsers (appletviewer, Netscape, IE).

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Java Standalone Applications

• Public class HelloWeb
• public static void main(String args)
• System.out.println(Hello Web!)
• Compilation
• javac HelloWeb.java gt HelloWeb.class
• Execution
• java HelloWeb

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Java Applets
Public class HelloWebApplet extend
java.applet.Applet public void
paint(java.awt.Graphs g) g.drawString(Hello
Web!, 125, 95) HTML lthtmlgt lth3gt Hello
Web Applet Example lt/h3gt ltapplet
codeHelloWebApplet width300
height200gt lt/appletgt lt/htmlgt
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Conclusions

• Java is a pure OO programming language
• Cross-platform applications
• (Write Once Run Anywhere)
• WWW Java gives the world a new way to think.