Air Force Institute of Technology

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Object-Oriented Programming DesignTopic 1 The
Java Environment

• Maj Joel Young
• Joel.Young_at_afit.edu

Maj Joel Young
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The Java Environment

• Java code is compiled to an intermediate form
  called bytecode
• The bytecode is executed by a simulated computer
  called the Java Virtual Machine (JVM)
• The JVM translates bytecode instructions to your
  machine

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The Java Environment

• Java maintains its portability by keeping the
  bytecode the same across all platforms
• The JVM specification is open so that vendors can
  write one for their platforms
• JVMs available from Sun, IBM, Microsoft, and
  others

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Java Programming Environment

• Sun Microsystems Java Development Kit (JDK)
• Available at www.java.sun.com
• Latest version is JDK 1.4.2
• Sun refers to all releases after 1.1.8 as Java
  2
• Contains compiler, JVM, and tools
• Java API Docs http//java.sun.com/j2se/1.3/docs/a
  pi/
• Integrated Development Environments
• Features include specialized editors, debuggers,
  GUI builders but be comfortable with command
  line first
• Recommended get up to speed fast
• Eclipse IBM http//www.eclipse.org/ (JDK
  1.3), libre
• DrJava http//www.drjava.org/, can interface
  with Eclipse, libre
• TogetherSoft R\Simulations\TogetherSoft
  (Academic Version)
• JBuilder www.inprise.com/jbuilder (free
  version)

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Example Java Program
class HelloWorld static public void
main(String args) // About the
simplest program you can // you can write in
Java // Print Hello World to the
console System.out.println(Hello World)

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Java Programming Environment

• Compiling the program javac HelloWorld.java
• Running the program java HelloWorld
• CLASSPATH environment variable
• Do not define it unless you know what you are
  doing
• If you do define it, ensure you include a
  period set CLASSPATH.c\java