Download Java Terms - Middle Tennessee State University

Java Terms
Middle Tennessee
State University
Fall, 2009
Java Terms
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Java Application Program – program that is
stored and run on a user’s local computer.
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Has a method called main()
Stored and run on user’s local computer
May be command-line or GUI interface
Java Applet – java program that is
embedded in a Web page.
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No method called main()
Methods are called by browser
Java Terms
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JSDK – Java Software Development Kit (also
called JDK for Java Development Kit)
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Primitive command-line tool set that includes libraries,
compiler, interpreter and applet viewer for testing Java
applets as well as other useful utilities
IDE – Integrated Development Environment
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Java development package for rapid development of Java
programs (edit, compile, build, debug)
Effort is required to learn how to use
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JBuilder by Borland (www.borland.com/)
Eclipse Open Source by IBM (www.eclipse.org)
NetBeans OpenSource by Sun (www.netbeans.org)
BlueJ - www.blueJ.org (free download)
JGrasp – www.jgrasp.com (free download)
Java Terms
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Java Class Library – predefined classes
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Java is a object oriented language
Use classes to set up objects
Java programs consist of the use of many classes
Java APIs – Java Application Programming
Interfaces
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Collection of existing classes in the Java class
library
Terms - Creating a Java Program
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Javac – Java compiler that translates Java source
code into bytecode
Bytecode is the language that is understood only by
a Java interpreter
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Is not machine language for any particular computer
Language for a fictitious computer called Java Virtual
Machine
Each computer will have its own bytecode interpreter
Bytecode interpreters are very simple compared to a
compiler
Example - compilation
Source file: Welcome.java
To translate to bytecode: javac Welcome.java
Result of translation: produces a file called
Welcome.class (bytecode)
To execute: java Welcome
Terms
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JVM – Java virtual machine – interpreter for
Java bytecode
appletviewer – program used as a
debugging aid when creating Java applets
Terms
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Package – group of related classes predefined by Java
Java Class Library – composed of many
packages
Core package
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Name of package begins with java
Example: the java.lang package
Terms
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Optional packages
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Example: the javax.swing package
Many packages are included in the Java Class
Library
 Java 2 Platform, Standard Edition (Java SE)
– includes the essential compiler, tools,
runtimes, and APIs for writing, deploying, and
running applications & applets
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Java 2 Platform, Enterprise Edition (Java EE)
– provides a component-based approach to
the design, development, assembly, &
deployment of enterprise applications.
Java 2 Platform, Micro Edition (Java ME) –
targets the consumer and embedded market
– used to write Java apps for cell phoned,
smart cards, etc.
Predefined classes
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System
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String
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Class defined in java.lang package
Class defined in the java.lang package
JOptionPane
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Class defined in the javax.swing package
Creates dialog boxes
Typical Java Environment
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Phase I – Create source program with an editor and
save with .java extension
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Phase 2 – Compile using javac
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File name must be the same as the class name
Produces bytecode with .class extension
Phase 3 – Loader – puts .class files in memory
Phase 4 – Bytecode Verifier – checks validity of
bytecode
Phase 5 - Interpreter
Java Conventions
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Class names begin with uppercase letter and
multiple word names are capitalized
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Example: public class Welcome
Example: public class WelcomeLetter
File names must be identical to class name
Files have one public class only.
Variables begin with lower case letters
Writing a Java Program
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Two types of programs
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Application programs
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Application programs
Applets
Standalone programs
Can be executed from any computer with a Java interpreter
Applets
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Special type of java program that can run directly from a
Java-compatible Web browser
Java Application Program
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Comments
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//This is a Java comment
/* This is a Java comment */
/** this is a Java comment */
Preferred method in certain cases
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/** This is best! We will find out why later!*/
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Called a javadoc comment
Used for documenting classes, etc
Java Modifiers
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Reserved words that specify properties of
data, methods, and classes
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public
static
private
final
abstract
protected
Statements/Blocks/Methods
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Every Java statement ends with a semicolon.
Blocks begin with { and end with }
Method – collections of statements that perform a
sequence of operations
Classes normally contain 1 or more methods
main Method (required) for Java Applications
//form of the main method
public static void main (String [] args)
{
/** statements
}
Example 1
/**
*The following Java Application
welcome message to the standard
*/
public class Welcome
{
public static void main (String
{
//Display a welcome message
System.out.println(“Welcome
}
}
program displays a
output.
[] args)
to the world of Java!”);
Example 2
public class Welcome
{
public static void main (String [] args)
{
//Display a welcome message
displayMessage();
}
public static void displayMessage()
{
System.out.println(“Welcome \n to the world of Java!”);
}
}
Good Web Sites
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http://java.sun.com/javase/6/docs/api/index.html
http://java.sun.com/docs/books/tutorial/java/
http://java.sun.com/docs/books/tutorial/java/TOC.html
The End