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3. Java Programming Language. Previously. What is a programming language? Set of grammatical rules for instructing a computer to perform specific tasks Languages by implementation Machine language; Assembly language Compiled languages; C, C++ Interpreted languages; Java
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3 Java Programming Language
Previously • What is a programming language? • Set of grammatical rules for instructing a computer to perform specific tasks • Languages by implementation • Machine language; Assembly language • Compiled languages; C, C++ • Interpreted languages; Java • Language by paradigm • Simple initial design • Divide project into smaller and simpler subprojects • Pseudocode
Overview • What’s Java? • Some history • Characteristics • Components • Type of programs • Development
Java is a programming language Created by Sun Microsystems Often used for web programming Initially marketed as a web development system Java is not only for web programming General purpose programming language Very similar to C++ simplified! What’s Java?
What Else? NOT JAVASCRIPT!!!!
James Gosling - Sun Started 1991, Launched 1995 "write once, run anywhere" WORA There were five primary goals : It should be "simple, object oriented, and familiar". It should be "robust and secure". It should be "architecture neutral and portable". It should execute with "high performance". It should be "interpreted, threaded, and dynamic". NOT Licensed to Microsoft - $20M Some history
Current 'Flavours' Java SE Standard Edition Java EE Enterprise Edition Servlets Java ME Micro Edition Optimised for mobile devices
Object Oriented Concurrent Interpreted Modular There's a library for (nearly) everything! Internationalization - utf8 native Memory Management Error Handling Characteristics
Components Byte Code Virtual Machine Operating System Hardware
Development / Distribution JDK Development Toolkit Compiler Header Files JRE Runtime Environment Just what's needed to execute bytecode
Type of programs • Applications • Has an entry point; static main method • Runable in a computer with JVM Library (y) Library (y) Library (y) Application Storage JVM OS
Type of programs • Applets • GUI applications • Applet is a program written in the Java that can be included in an HTML page Applet Storage Web Server Library (y) Library (y) Library (y) Browser OS
Type of programs • Servlets • Applications that run on the server side, so has an entry point • Normally used to extend functionality of a Web Library Library Storage Servlet Web Server JVM OS
Type of programs • Libraries • Re-usable code • Cannot be run by itself; doesn’t have an entry point Library (y) Library (y) Library (y) Application Storage JVM OS
Development • Java Development Kit (JDK) http://www.oracle.com/technetwork/java/javase/downloads/index.html • Eclipse Development Environment Penumbra is in http://wiki.eclipse.org/Eclipse_IDE_for_Education • Documentation for Java libraries http://download.oracle.com/javase/6/docs/api/ • Tutorial http://download.oracle.com/javase/tutorial/index.html
Eclipse Rapid Application Development Very Powerful Most commonly used RAD today For (just about) all Languages Can be very complex So - we are using Penumbra Special Educational Edition