Java Development Kit

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Java Development Kit

• Dr. Robert Stumpf, Professor
• Computer Information Systems

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Java Development Kit

• JDK (Java Development Kit) Components
• Now also called the SDK (System Development Kit)
• Use of the command prompt
• Using it with jars and packages

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JDK Components

• Java files
• Contain the source code
• Must be named with the extension java
• For example
• Program1.java
• Note class name equals file name

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JDK Components

• Class files
• Contain the intermediate code
• The intermediate code is interpreted by a virtual
  machine which converts it "on the fly" to
  appropriate binary code
• Must be named with the extension class
• For example
• Program1.class

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JDK Components

• Jar files
• Contain both the java and class files
• Can also contain other files such as jpegs and
  gifs
• Are understood by win zip
• Contains a manifest file that is a directory of
  the contents enabling it to executed
• For example
• program1.jar

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Use of the Command Prompt

• javac.exe - The Java compilerproduces byte code
  from Java source code
• Example of use javac Program1.java
• Note again that the file name is the same as the
  class name

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Use of the Command Prompt

• java.exe - The Java interpreter runs the Java
  byte code
• Example of use java Program1
• Note that the file name is Program1.class
• Note also that extension is left offwhen running
  it

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Use of the Command Prompt

• appletviewer.exe - The Java interpreter runs the
  Java byte code
• Example of use appletviewer.program1.html
• Requires a web page such as

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Use of the Command Prompt

• lthtmlgt
• ltheadgt
• lt/headgt
• ltbodygt
• ltapplet
• codeprogram2.Program2.class
  archiveprogram2.jar width250 height300gt
• lt/appletgt
• lt/bodygt
• lt/htmlgt

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Using it with jars and packages

• jar.exe - The Sun jar utility
• Creates, adds files, updates, extracts and lists
  files to and from a jar
• For example
• jar cvf program1.jar Program1.class - Create
• jar uvf program1.jar MyPanel.class - Update
• jar xvf program1.jar MyPanel.class - Extract
• jar tf program1.jar - List

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Using it with jars and packages

• Explanation
• jar cvf program1.jar Program1.class - Create
• jar uvf program1.jar MyPanel.class - Update
• jar xvf program1.jar MyPanel.class - Extract
• jar tf program1.jar - List
• c create x extract f archive file
• u update t list v verbose output

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Use of Command Prompt

• Using Command Prompt
• To start (Windows 2000) use Start -gt Programs
  -gt MS-DOS Prompt (might also be under
  accessories)
• To use first set path set pathc\j2sdk1.4.0\bin
  path
• Assumes the SDK was installed in the root of C
  drive adjust as necessary
• Many users put this set path in the autoexec.bat
  file or in their system registry

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Use of Command Prompt

• After setting path, run your program as follows
• c\javac Program1.java
• c\java Program1
• If class is in a package, use
• c\javac classpath mypackage.
  mypackage/Program1.java
• c\java classpath mypackage.
  mypackage/Program1
• Assumes Program1.java is in a sub-directory
  called mypackage
• All class files will appear in the the
  subdirectory

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Use of Command Prompt

• Building a jar called program1.jar jar cvf
  program1.jar program1\.classNote jar name is
  same as package name and wild card used in jar
  command.
• Using a jar called program1.jar
• c\ java -cp program1.jar program1.Program1
• Note package name is always used with class name

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Use of Command Prompt

• After setting path assuming using two jars called
  program1.jar and my.jar
• c\java -cp program1.jarmyjar.jar
  mypackage/Program1
• Assumes both program1.jar and myjar.jar are in
  the current directory
• A semi colon is the separator character
• -cp is an abbreviation for classpath that only
  works with the java command

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Summary

• The JDK or SDK is used world wide on many
  platforms
• It is the back up system to use when workbenches
  such as Eclipse are not available
• The JDK is something all employers expect you to
  know

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Closing

• Real Programmers should know
• how to use the JDK
• Thank You
• Robert Stumpf
• email rvstumpf_at_csupomona.edu
• url www.csupomona.edu/rvstumpf