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EE2E1. JAVA Programming Introduction Dr. Mike Spann [email protected] Contents Java is just another programming language (eg. C & C++). So why bother to learn Java? Java is …… Portable Object oriented Robust Multi-threaded Graphical Connected Extensive Java applications and applets Applications – standalone Java programs Applets – Java programs that run inside web browsers ‘Hello world’ application /** * The HelloWorldApp class implements an application that simply displays "Hello World!" to the standard output. */ public class HelloWorldApp { public static void main(String[] args) { System.out.println("Hello World!"); } } ‘Hello world’ applet class HelloWorldPanel extends JPanel { public void paintComponent(Graphics g) { super.paintComponent(g); Font f=new Font(“SansSerif”,Font.BOLD,36); g.setFont(f); g.drawString("Hello World!", 50, 120); } } public class HelloWorldApplet extends JApplet { public void init() { Container contentPane = getContentPane(); contentPane.add(new HelloWorldPanel()); } } ‘Hello World’ html file <APPLET CODE = “HelloWorldApplet.class" WIDTH = 300 HEIGHT = 300 > </APPLET> Run the ‘Hello World’ applet http://www.eee.bham.ac.uk/spannm/Java %20Stuff/HelloWorldApplet/HelloWorld Applet.html Portable Java Java is ‘program once – run anywhere’ A Java program is compiled to bytecodes Bytecodes interpreted by the Java Virtual Machine Object Oriented Java Object oriented programming is concerned with objects and their : State Behavior Example A bank account State balance account number transfer() Behaviour withdraw() class BankAccount { public void transfer(int amount); public void withdraw(int amount); private: int balance; int accountNumber; } Robust Java Java is easier than C or C++! Java has better memory management than C or C++ You don’t need pointers for accessing arrays or strings in Java No chance of dangling pointers or memory leaks in Java Multi-threaded Java A thread is a sequence of executing statements in a program A multi-threaded program comprises a number of threads which run in parallel (but only one thread is being executed at one time) Java supports multi-threading as an intrinsic part of the language – multithreading is easy in Java! A single-threaded program A multi-threaded program Example – A sort demo Multi-threaded Sorting Applet Graphical Java Abstract widget toolkit (AWT) + User interface library Swing Swing is a collection of user interface components (buttons, menus, dialogue boxes etc) AWT does the event handling Example 1. A tic-tac-toe applet http://www.eee.bham.ac.uk/spannm/Java %20Stuff/TicTacToeApplet/example1.htm l Example 2. Full swing set demo http://www.eee.bham.ac.uk/spannm/Java %20Stuff/SwingSetApplet/SwingSetApp let.html Connected Java Networking is easy in Java! Java has classes and methods for network programming. A Java program can easily access a website through a URL connection Java programs can be be written which implement both client and server side processing Example – simple web browser http://www.eee.bham.ac.uk/spannm/Java %20Stuff/BookMarkApplet/BookMark.h tml So what is Java? Java consists of 2 things : The Java Virtual Machine (Java VM) The Java Application Programming Interface (Java API) Java VM runs the Java bytecode on the different hardware platforms Java API is a large collection of readymade software components You can add additional API’s to this layer Graphics, numerical, image processing etc The Java API is grouped into libraries of related classes and interfaces; these libraries are known as packages. My Java program Java API Java VM Hardware Other API’s Java API java lang Math awt Graphics sqrt() exp() Button Math String Color Thread io File InputStream OutputStream Java API documentation can be found online at : http://docs.oracle.com/javase/7/docs/api/ Extensive Java – Java technology Java has additional API’s covering a wide range of software technologies Java2D – 2D graphics Java3D – 3D graphics Java Advanced Imaging (JAI) – image processing Java Speech API – speech processing Java Media Framework API – multi-media application JavaBeans – re-useable user interface components Java Servlets – extending web server functionality Java Message Service (JMS) – allowing programs to exchange messages Java Telephony API – computer telephony Java TV API – interactive digital TV JavaMail API – email applications JDBC – Java database API Examples Java2D API http://www.cs.kent.ac.uk/people/staff/pgk/te aching/java/lab-guides/gettingstarted/demo/jfc/Java2D/Java2D.html Java 3D API http://www.mol3d.com/ Java resources Sun’s Java home page http://java.sun.com/ Java online tutorial http://java.sun.com/docs/books/tutorial/ Comparing C++and Java http://www.compapp.dcu.ie/~renaat/projects/cvjava.ht ml Textbook Core Java 2. Volume 1-Fundamentals C.S.Horstmann, G. Cornell Amazon Link My web page http://www.eee.bham.ac.uk/spannm/Courses/ee2e.h tm OK, so why should I learn Java? Main reason, Java is object oriented What is OOP good for? Modelling asynchronously interacting objects • GUIs • Event simulation • Ray tracing visualisation • CAD simulation • Real-time control/embedded systems • Robotics • Image/Video processing • Client/Server systems • etc OK, so why should I learn Java? Java is free to download and is easy to learn Java has powerful (and free!) development tools e.g. Eclipse , Netbeans Excellent documentation support – Javadocs Great community support Rich collection of open source libraries Can develop Android apps in Java – supported by Eclipse and Netbeans Android is a good platform for mobile apps because of ease of release, wide range of devices and its an open platform So what about this course? EE2E1 (MS) Introduction to Java programming Basic ideas about objects and classes We will also look at more advanced features of Java • Graphics • Files and streams • Multi-threading • Networks EE2E2 (DP) Object Oriented Software Design Assessment EE2E1 and EE2E2 are assessed jointly (making up the EE2E module) EE2E1 is assessed through a classtest and programming exercises and a major programming assignment 15% through a 1 hour class test 2 x 22.5% through 2 programming exercises 40% through a major programming assignment carried out in semester 2