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Introduction to Java

Introduction to Java. Session 1. Objectives. Discuss the brief history of Java. Discuss Java in brief Explore the types of Java programs Discuss what we can do with Java? Examine the differences between Applets and Applications Describe the Java Virtual Machine (JVM)

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Introduction to Java

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  1. Introduction to Java Session 1

  2. Objectives • Discuss the brief history of Java • Discuss Java in brief • Explore the types of Java programs • Discuss what we can do with Java? • Examine the differences between Applets and Applications • Describe the Java Virtual Machine (JVM) • Explore the features of some IDE’s • Discuss the JDK and tools under it • Discuss future trends and technologies Introduction to Java / 2 of 28

  3. Introduction to Java • Java being secure, portable and platform independent was found to be capable of addressing large scale problems across the Internet • Introduced in 1995 by Sun Microsystems • Objective was to develop a software for embedding in consumer electronic devices • Initially called ‘Oak’ • Internet users had problems of portability and platform independence Introduction to Java / 3 of 28

  4. What is Java? • A cross platform language • It is used for stand-alone applications, net based programs and to program consumer devices • For e.g.: cellular phones, palm pilots • An object-oriented programming language Introduction to Java / 4 of 28

  5. Java and the internet • Applets can respond to user input and actions • Programs on the Net are either static or dynamic • Applets help develop dynamic programs • Applets run on Java enabled web browser Introduction to Java / 5 of 28

  6. Security issues (1) • This can be a potential risk for the user’s system • An Applet has to be downloaded on the user’s system before it can work • Hence, applets are restricted from accessing all areas of the disk Introduction to Java / 6 of 28

  7. Security issues (2) • JVM generates byte codes as a result of compilation • Byte codes cannot be executed without the JVM • This control is exercised by the Java Virtual Machine (JVM) Introduction to Java / 7 of 28

  8. Types of Java programs (1) • Applets • Programs created specially to work with the Internet Displays an image GUI to accept user input Introduction to Java / 8 of 28

  9. Types of Java programs (2) • Command line applications • Java programs that run from a command prompt and do not display any GUI screen Introduction to Java / 9 of 28

  10. Types of Java programs (3) • GUI Applications • Java programs that run stand-alone and accept user input through a GUI based screen Introduction to Java / 10 of 28

  11. Types of Java programs (4) • Client sends request which is processed by the server • The server side APIs extend capabilities of standard APIs and are known as Servlets • Also called server side applets • For e.g. – HTML form processing, process databases and perform server side transactions • Servlets • Suitable for web based n-tier application development Introduction to Java / 11 of 28

  12. Types of Java programs (5) • A programmer can create his/her own packages or use the built-in packages • java.awt, java.io and java.applet are some examples • Database applications • Uses JDBC API for database connectivity • Programs can be either applets or application • Packages • Class libraries in Java Introduction to Java / 12 of 28

  13. What can we do with Java? • Colorful scrolling banner for web pages • Interactive quiz • A program that plays audio, displays a banner and animates images at the same time • Interactive games that can run as stand alone or deployed on the web • Create a wide variety of applications from a simple computation program to complex distributed application • One can develop: Introduction to Java / 13 of 28

  14. Do not need a browser to execute These run within JVM Executed in a java compatible web browser Applets load and run on a Java-enabled web browser Difference between Applets and Applications (1) Applets Applications Introduction to Java / 14 of 28

  15. Manages its own flow of execution No restrictions about reading or writing from/to the local file system Flow of execution is partly managed by the browser context Cannot read/write from/to the local file system Difference between Applets and Applications (2) Applets Applications Introduction to Java / 15 of 28

  16. Similarities in Applets and Applications (1) • Both can use the Abstract Windowing Toolkit (AWT) • Both need to use the standard Java class libraries Introduction to Java / 16 of 28

  17. Java Virtual Machine (JVM) • Java code can run on any platform by using JVM • JVM normally reads and executes Java statements one at a time • JVM is responsible for platform independence and small size compiled code • Recognizes only a particular binary format called a class file • Has an interpreter component that enables communication between Java byte code and a computer’s operating system Introduction to Java / 17 of 28

  18. Visual development tools • Simplifies the software development process • Includes class browser for viewing and navigating through the class hierarchy • Includes a source code editor that helps code programs • Helps in quick and efficient development of Java applications and applets Introduction to Java / 18 of 28

  19. Some visual development tools • Borland Jbuilder from Borland/Inprise • Includes an integrated editor, debugger, compiler, visual designer, wizards and sample applications • Forte for Java, Community Edition from Sun Microsystems • Integrated visual design, editing, compilation and debugging capabilities to create applets and applications • Visual Age for Java from IBM • Works with existing databases, applications and transactions Introduction to Java / 19 of 28

  20. Java Development Kit (JDK) • Basically a set of command line tools • Three major releases are : • Java 1.0 – first release • Java 1.1 – 1997 release • Java 2 – latest release • Freely available at Sun’s official website • Contains the software and tools needed to compile, debug and execute applets and applications Introduction to Java / 20 of 28

  21. Tools under JDK (1) • Syntax : javac [option] source • Source files end with extension .java • Options can include – • -classpath • -d • -g • -o • -verbose • javac : compiler used to compile Java source code Introduction to Java / 21 of 28

  22. Tools under JDK (2) • java [option] classname [arguments] • Options can include • -classpath • -Dname name • -help • -v or –verbose • -X • java: interpreter used to execute Java byte codes Introduction to Java / 22 of 28

  23. Tools under JDK (3) • javadoc : This is the Java documentation tool • Generates detailed documentation in HTML form for any .java source code or package • appletviewer : Used to view and test applets • Syntax : appletviewer [options] url Introduction to Java / 23 of 28

  24. New features in Java2 (1) • Drag and Drop – interactively transferring information across different applications and from one part of a program’s interface to another • Swing– new set of classes and interfaces used to create an advanced GUI Introduction to Java / 24 of 28

  25. New features in Java2 (2) • Java Sound – totally new set of features pertaining to Java’s audio features • RMI– Remote Method Invocation allows applications to call objects located at remote sites and communicate with them • Java 2D API– set of classes for advanced 2D graphics and imaging Introduction to Java / 25 of 28

  26. Present Java technologies (1) • Support for distributed computing in the form of features such as RMI • Database management support in the form of JDBC • Reusable software components in the form of JavaBeans • Creation and deployment of applications that can run on any operating system Introduction to Java / 26 of 28

  27. Present Java technologies (2) • Java 2 Enterprise Edition (J2EE) which includes : Enterprise Java Beans (EJB) Java Server Pages (JSP) Java Servlets Introduction to Java / 27 of 28

  28. Future trends • Miniature devices such as Palm pilots and mobile phones are equipped with a features such as email, gaming options and many others • They are based upon Java 2 Micro Edition (J2ME) • New products in the area of embedded technologies for consumer devices by making use of mobile computing Introduction to Java / 28 of 28

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