1 / 26

JAVA BASICS

JAVA BASICS. Why Java for this Project?. Its open source - FREE Java has tools that work well with rdf and xml Jena, Jdom, Saxon Can be run on UNIX,Windows,LINUX,etc GUI/Applet capabilities Igor’s application WE NEED TO LEARN IT ANYWAY! . How to run. JDK – Java Development Kit

Download Presentation

JAVA BASICS

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. JAVA BASICS

  2. Why Java for this Project? • Its open source - FREE • Java has tools that work well with rdf and xml • Jena, Jdom, Saxon • Can be run on UNIX,Windows,LINUX,etc • GUI/Applet capabilities • Igor’s application • WE NEED TO LEARN IT ANYWAY!

  3. How to run • JDK – Java Development Kit • Basic compiler, linker, and libraries • IDE – Integrated Development Environment • NetBeans – netbeans.org

  4. How to run • Types of files • .java – source code • .class – executable code • .jar (java archive) - bundle of multiple files Tutorial - http://java.sun.com/docs/books/tutorial/jar/basics/index.html • Packages – groups of related classes in a directory

  5. How to run • Applications • javac – java compiler • Commandline - javac classname.java • java – executes application • Commandline - java classname • Jikes – faster version of java command • http://oss.software.ibm.com • Commandline – jikes classname

  6. How to run • Environment Variables • Path – searches computer for executeable • Classpath – searches computer for classes that need to be used

  7. How to run • Applets – java applications that are embedded in html and run in a browser • Appletviewer – shows sample in browser • Commandline – appletviewer appletpage.html

  8. How to run • Make – (if you are sick of javac and java) • Defines which components go together to make a program. • Defines how to "put the pieces together". • Keeps track of dependencies among components. • Helps avoid doing unnecessary work and forgetting to do necessary work

  9. How to run • Makefile – example default: javac Animal.java note: there is a tabspace in front of javac Commandline – make - This compiles the file called Animal.java

  10. How to run • Makefile – example Tiger.java: Tiger.java Animal.class javac Tiger.java Animal.class must exist for tiger.java to compile Commandline – make tiger.java

  11. How to run • Makefile – example all: Tiger Animal Tiger: javac Tiger.java Animal: javac Animal.java Commandline – make all “all” triggers both Tiger and Animal to compile

  12. How to run • ANT • Similar to make in that it stores in a project • Apache application • See handout

  13. Java Programming • Import • “includes” a predefined java package that will be used in a program • Statements made outside of the code • Package must be contained in a directory given in the classpath • * denotes search entire directory • Example Import java.applet.Applet; Public class BinarySearch extends JApplet { …}

  14. Java Programming • Important predefined java classes • Java.io.* - i/o files and streams • Java.awt.*,java.swing.* - GUI tools • Java.util.* - data structures • Java.applet.Applet – applets • Java.servlet.* - used for scripts, tomcat and other interactive servers • Java.sql.* - used for sql handling • Java.net.* - network apps

  15. Java Programming • Package – used for user defined packages • Command used when wanting to include the class in a package • Used outside class declaration • Example package john.harney.example; Public class whatever {…} • Assuming the current directory is default, this statement will place the whatever.class in the default/john/harney/example directory • Commandline – javac –d . Whatever.java

  16. Java Programming • General Format /*import and package statements here*/ public/private/protected class classname{ … Member variables Constructors Methods (member functions) … } • File must be saved as “classname.java” • Main (like c++) is executeable for an application (public static void main(args)) • Class must be compiled in order to be used by another class

  17. Java Programming • Executable example (Welcome3.java) public class Welcome3 { // main method begins execution of Java application public static void main( String args[] ) { System.out.println( "Welcome\nto\nJava\nProgramming!" ); } // end method main } // end class Welcome3

  18. Circle.java example (Java vs C++) • Class Header • Instead of: class Circle : public Point • There is: public class Circle extends Point;

  19. Java Programming • Circle.java example (Java vs C++) • Member variables • Instead of: private: double radius; • There is: private double radius;

  20. Java Programming • Circle.java example (Java vs C++) • Constructors • Instead of: Circle(int x,int y, double radiusValue); • There is: public circle(int x,int y, double radiusValue); Note: “public” denotes that this may be constructed outside of the class declaration

  21. Java Programming • Circle.java example (Java vs C++) • Member functions (methods) • Instead of: double getRadius() { return radius; } • There is: public double getRadius() { return radius; } Note: “public” denotes that this may called outside of the class

  22. Java Programming • Circle.java example //assume the compiler can find circle.class Import javax.swing.JOptionPane; //allows GUI input public class CircleImplement { // main method begins execution of Java application public static void main( String args[] ) { Circle circ = new Circle(2,2,4.0); //constructor double rad = circ.getRadius();//calls to method getRadius JOptionPane.showMessageDialog(null,rad); //prints radius } // end method main } // end class Welcome3

  23. Java Programming • Other notable differences between Java and C++ • Strings are immutable • No global variables • Memory allocation is not needed (ie no pointers) • Garbage Collection • No operator overloading

  24. Javadoc • Javadoc – gives info about a source file • Commandline – javadoc class.java • Gives html documentation on the variables, methods, inheritence, other comments, etc. • Format – see handout

  25. JDOM • JDOM – java class that enables XML construction and parsing • Handout

  26. Saxon • Saxon - http://saxon.sourceforge.net/saxon6.5.3/index.html • Supports XSLT,XPath,XQuery • Can be used with JDOM • Commandline java  classname sourcexml > destinationxml

More Related