Java

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Java & concept explained easily

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Java

  1. 1. Java How to find, install and begin to use the Java programming language.
  2. 2. A word or two on the history of some old fashion programming languages A small history of Java… How do I install it on my computer? How do I use what I just installed? What we’re going to cover
  3. 3. A short look at some old school languages, BASIC, C and C++ It all begins in the sixties…
  4. 4. BASIC BASIC stands for Beginner’s All-purpose Symbolic Instruction Code. It was designed in 1963 at Dartmouth college. It was designed to make it easy for non-technical people to write computer programs. BASIC programs were like grocery lists. You told the program what you wanted to do and it did it in order. BASIC was Interpreted.
  5. 5. C and C++ Developed in the early seventies, “C” became the de-facto language for microcomputer programming in the seventies and eighties. “C” was not interpreted, it was compiled. __________ Later, in the early eighties, C++ introduced object orientation to the C world. Originally called “C with Classes”, Bjarne Stroustrup developed the additions to C that, in 1985, became C++. OO is when programmers try to mimic the real world more closely and make programs act like “objects” and not just be grocery lists.
  6. 6. So, what have we learned? 1. BASIC was an interpreted programming language 2. “C” was a compiled programming language 3. “C++” brought object orientation to “C”
  7. 7. Say goodbye to the seventies and welcome to a short (but hopefully informative) history of the Java programming language Authentic Seventies Nerds
  8. 8. James Gosling began developing Java beginning in 1991 It was first called “Project Green” and ‘Oak” First developed for remote cable TV boxes James Naughton creates “HotJava” in 1995. it’s a web browser that lets you run “Applets”. The entire browser is written in Java. In 1998 Java 1.2 is released Java just released version 1.6 or J2SE 6… James Gosling Circa 1971 James Gosling Today
  9. 9. Java Buzzwords Simple Object Oriented Architecture Neutral Portable Multithreaded High Performance – JIT Buzzwords glommed from the Core Java 2 book verbatim
  10. 10. FREE
  11. 11. Is Java Interpreted or Compiled?
  12. 12. Is Java Interpreted or Compiled? BOTH!! Java programs are compiled to Bytecode Bytecode is then interpreted by a JVM, or Java Virtual machine. The virtual machine is what runs your program It’s the JVM that cares about your Operating system, NOT THE PROGRAM! WORA - Write Once, Run Anywhere!
  13. 13. Is Java Object Oriented?
  14. 14. Is Java Object Oriented? YES! Every bit of code in a Java program is in a “Class” Code Reuse, Encapsulation, Polymorphism, Inheritance
  15. 15. DUKE! Why? Who knows…
  16. 16. Downloading a Java JDK You want a JDK, not just a JRE Create a “Temp” directory on your PC or laptop Go to http://java.sun.com Go to the “Popular Downloads” section and select “Java SE” Select a JDK without Netbeans (We’ll talk about this later) Agree to the accept the use policy Right Click and Save the Offline Windows JDK to your temp dir
  17. 17. Installing a Java JDK Go to your “Temp” dir using Windows Explorer Make sure no other apps are running and double click the install program you just downloaded. Follow the steps. I install in C:Java Watch fom multiple JREs and JDKs! In Windows the Registry runs the show now, not the JAVA_HOME env variable Test with a Command Prompt Window and “java –version” Add C:Java”Java ver”bin to your PATH var Be sure to add “current directory” to the CLASSPATH (if you had one)
  18. 18. Now, Lets test it DOS - Command Prompt Make a directory structure Type “Edit” and Voila PSVM Test JAVAC and JAVA Create Bytecode ( the *.class file) with “Javac” Run Program with “Java”
  19. 19. If we were lucky we got something that looks like this…
  20. 20. Help on the Web http://java.sun.com/javase/6/docs/api/ http://www.javaranch.com http://java.sun.com/docs/books/tutorial/ http://www.sorcon.com/java2/ http://remus.rutgers.edu/freestuff Got an Error? Just type it verbatim into Google and you usually can find the answer to your question or solve your problem. Wikipedia is a good place to get background and history On anything, and Java is no exception
  21. 21. Remember…. Java is both compiled and interpreted Java is Object Oriented http://java.sun.com is Java’s home You want the Java Development Kit (JDK) , not a JRE or J2EE Take your time, use temp directories for setup files Test with a simple “Hello World” after you install Use the Web for help (Google errors, javaranch, etc.)
  22. 22. THANK YOUhttp:remus.rutgers.edujavaworkshops Any questions or comments can be sent to me At biglars@cs.rutgers.edu Be Good Now… ©2007 Rutgers University & Lars Sorensen

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