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MELJUN CORTESJava Programming Introductory


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MELJUN CORTESJava Programming Introductory

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MELJUN CORTESJava Programming Introductory

  1. 1. MELJUN CORTES, MBA,MPA,BSCS,ACS Java Programming (for designers)
  2. 2. What is a Program? A list of detailed instructions that the computer carries out To make a cup of coffee the following would not be sufficient: 1.1. Go to kettle 1. Boil water 1.2. Check kettle has water in it 2. Put coffee in cup 1.3. If not 3. Pour in hot water 1.3.1 Take kettle to cold tap 4. Add milk 1.3.2 Remove lid of kettle 1.3.3 Put kettle under cold tap The instructions would have 1.3.4 Turn on tap to be much more detailed: 1.3.5 When kettle full turn off tap 1.3.6 Return kettle to worktopYou have to say exactly what to do in the rightPlug kettle into mains 1.4. order with no ambiguity 1.5.Switch on electricity …….
  3. 3. Java is…• Platform-independent X• Apps for mobile phones and other X consumer devices• Secure, portable, multithreaded X• Online, server-side applications X?• Simple, Object oriented ☺• GPL libraries ☺
  4. 4. Get started• Two components: – Java Virtual Machine (VM) • Base for the Java platform, install Win version – Java Application Programming Interface (API) • Prewritten code, organized into packages of similar topics. Each package or library contains classes and interfaces that you can call and extend. Example: – Rectangle2D = new Rectangle2D(loc, width, height)•
  5. 5. Acronyms• JDK or J2SE, Development Kit – Set of Java development tools, consisting of the API classes, a Java compiler, and the Java virtual machine (VM) interpreter – The JDK is used to compile Java applications and applets. The most current version is the J2SE 5• J2SE, Runtime Environment 5.0
  6. 6. Set up: Download the JDK• And set the classpath in Windows Include the directories where you will run Java apps
  7. 7. Set Up a Development Environment• NetBeans IDE, JEdit, Eclipse, JCreator• Or use a simple text editor, and compile and run from the command line
  8. 8. Set Up• Download J2SE 5.0 Documentation• Look for useful libraries
  9. 9. Some Useful Libraries• Colt: or High Performance Scientific and Technical Computing• Weka 3: Data Mining Software in Java• JHotDraw is a two-dimensional graphics framework for structured drawing editors• JGAP is a genetic algorithms component written in the form of a Java package• OpenAI: a full suite of Artificial Intelligence components: Agents, Neural Nets, GAs…• JUNG:Java Universal Network/Graph Framework• JOONE: JGAPs genetic algorithms to evolve neural nets• HyperGraph: to work with hyperbolic geometry and especially with hyperbolic trees• Repast: an agent modeling toolkit (like Swarm)• JExcel or JXL provides the ability to read, write, and modify Microsoft Excel spreadsheets
  10. 10. Standard Java Libraries• Language • JAI: Advanced• Maths Networking• Graphics • Imaging• 2D • XML• 3D • Print• File I/O
  11. 11. Swing• GUI-control (widget) library in Java 2• Built-in controls, flexible and customizable• Features aimed at interface design – Buttons, tabbed panes, dockable toolbars, scroll panes, tooltips, tables, etc.• Look & feel can be changed
  12. 12. Java 2D• Standard drawing library in Java 2• Drawing attributes – Fill patterns and images – Fonts – Line thicknesses and dashing patterns – Colour mixing rules and transparency• Transformations – Floating-point coordinate system – Mapping from memory coords to screen or printer coords – Affine transforms: translate, scale, rotate, and shear
  13. 13. Java 3D• Extension to Java – Not part of “core” Java language like Java 2D• Built on Direct3D or OpenGL, depending on platform• Scene-graph based model, not primarily immediate-mode rendering
  14. 14. Java Versions• Java 1.0, 1.1… “Java 2” refers to 1.2 onwards• Popular: 1.4.2• New: 1.5. The leading "1." is dropped, now it is Java Platform Standard Edition 5.0• But… version 5.0 also keeps the version number 1.5.0 in some places visible only to developers• This release is also known as “Tiger” (not the latest Mac OS X!)
  15. 15. Jargon• Application is a stand-alone Java program• Applet is a browser-based Java program
  16. 16. Basic Procedure1. Write a .java file2. Compile it with the javac command3. Now you have a .class file4. Run it with the java command5. Voilá!
  17. 17. Running a Java ApplicationWrite IDE or Save the fileJava Text with a .javacode Editor Java code: extension Run the Java javac This creates compiler a file of javac bytecode with a .class Bytecode: extension User to interact MyProg.class with the system Execute the bytecode with the java MyProg Output command java Program to execute and produce a data set, graphs, etc.
  18. 18. Java program layout• A typical Java file looks like: import java.awt.*; import java.util.*; public class SomethingOrOther { // field and method definitions . . . } This must be in a file named !
  19. 19. What does it mean? This line announces that the program These 2 lines tell the computer to include (class) can be run by anyone (public), is (import) two standard libraries awt (Abstract called Greetings and is an Applet. Window Toolkit) and applet. import java.awt.*; import java.applet.Applet;This line declares what public class Greetings extends Applet {follows in the { } as amethod called paint. public void paint(Graphics g) { g.drawString("Hello World!", 50, 50); } }This line tells the computer todisplay some text (a string) on the This is where it is displayed in This is what is displayedscreen. pixels across and down from the top left hand corner
  20. 20. A Java Class• Java programs are collections of classes• OOP: – A class that represents a rectangle would contain variables for its location, its width, and its height – The class can also contain a method that calculates the area of the rectangle – An instance of the rectangle class could contain the information for a specific rectangle, such as the dimensions of a room
  21. 21. An Applet is a Panel is a Container… is an Object java.lang.Object | +----java.awt.Component | +----java.awt.Container | +----java.awt.Panel | +----java.applet.Applet…so you can do things with it that you’d do withapplets, panels, containers, components, and objects.
  22. 22. Object Oriented (OO) ProgrammingA key aspect is Inheritance.You don’t have to describe similar objects completely. You candefine a superclass (sometimes called base class) that has thecommon attributes and methods and inherit these adding only theones that are different. Vehicle Attributes: Speed, Colour Methods: Start, Stop These are inherited Attributes: Max Attributes: Passengers Bus Lorry Max Load Methods: Pick up Methods: Passengers Pick up Load
  23. 23. What classes, why?• A file can contain multiple classes, but only one can be declared public, and that one’s name must match the filename – Usually 1 class = 1 file• Most difficult part is to plan the program: the classes, the methods, the variables, the procedure – If you can define it in paper & pencil, the rest is easy
  24. 24. Methods• Define a group of statements that perform a particular operation• With or without arguments calculateArea(shape) { // here geom operations } createShape() { // new square... // calculateArea(square) }
  25. 25. Primitives and Objects• Java distinguishes two kinds of entities – Primitive types – Objects• Primitive types: integers, doubles, booleans, strings…• Objects are associated with reference variables which store an object’s address
  26. 26. Expressions• Assignment statements: =, +=, *= etc.• Arithmetic uses the familiar + - * / %• Java uses ++ and --• Java has boolean operators && || !• Java has comparisons < <= == != >= >
  27. 27. Control statementsif (x < y) smaller = x;if (x < y){ smaller=x; sum += x;} else { smaller = y; sum += y; }while (x < y) { y = y - x; }do { y = y - x; } while (x < y)for (int i = 0; i < max; i++) sum += i;
  28. 28. The main method• Every Java application must contain a main method: – public static void main(String[] args)• An application executes the main method first. The array of Strings can be empty or it can receive arguments to customise how the program runs (number of iterations, number of agents, etc).
  29. 29. ExampleAn Evolutionary Design System
  30. 30. public static void main(String[] args) { new Model(); }public Model() { EvoDesign frame = new EvoDesign(); frame.setVisible(true); }
  31. 31. public EvoDesign() { jbInit();}private void jbInit() throws Exception { setSize(new Dimension(860,680)); setTitle("Evolutionary Design"); jMenuFile.setText("File");… setJMenuBar(jMenuBar); JComboBox jGens… JList jListFns… JButton jRun… jTabs.addTabs… contentPane.add(…);}void jTabs_clicked(ChangeEvent e) { … }void jLists_mouseClicked(MouseEvent e) { … }
  32. 32. Image makeFitnessLines(Image im) { LineGraph bg = new LineGraph(); bg.setDefaultLineThickness(0.1); … try { new ImageOutput(im); out.render(bg); im = out.getImage(); }}void jMenuExit_actionPerformed(ActionEvent e) { System.exit(0);}class drawPanel extends JPanel { public void paint(Graphics g) { g.setFont(EvoDesign.myFont); g2.drawImage(new BufferedImage(0, 50, 2); }}
  33. 33. public void setupGA() throws Exception { fitnessHistory = new DoubleArrayList(); topFitness.clear(); Configuration conf = new DefaultConfiguration(); conf.addGeneticOperator( new MutationOperator(mut) ); conf.addGeneticOperator( new CustomCrossover(cross) ); FitnessFunction myFunc = new FitnessFn(chrom); conf.setFitnessFunction(myFunc); Gene[] g = new Gene[chrom]; g[0] = new BooleanGene(); g[i] = new IntegerGene(1, alle); Chromosome sampleChromosome = new Chromosome(g); conf.setSampleChromosome(sampleChromosome); conf.setPopulationSize(EvoDesign.pop); genPopulation = Genotype.randomInitialGenotype(conf); Chromosome best = genPopulation.getFittestChromosome();}
  34. 34. public FitnessFn(int a) {}public int evaluate(Chromosome a) { int fitness = 0; Gene[] gs = a.getGenes(); if (EvoDesign.fnCrit.equals("minMean")) { fitness += ( EvoDesign.alle - Descriptive.mean(sd) ); } return Math.max(1, fitness);}
  35. 35. public Colours01() { setColorPalettes();}public static BufferedImage makeOutputImage() { for (int i = 0; i < topSolutions.size(); i++) { Chromosome s = topSolutions.get(i); for (int j = 0; j < s.size(); j++) { Gene si = s.getGene(j); g2.setColor( getAllele() .intValue()); g2.fillRect(boxX, boxY, stepX, 25); } } return bf;}
  36. 36. Code• Get these slides and the source code for the example at: