Java & concept explained easily

1. Java
How to find, install and begin
to use the Java programming
language.

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. A short look at some old school
languages, BASIC, C and C++
It all begins in the sixties…

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. 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. 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. Say goodbye to the
seventies and
welcome to a
short (but hopefully informative)
history of the Java
programming
language
Authentic Seventies
Nerds

9. 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

10. Java Buzzwords
Simple
Object Oriented
Architecture Neutral
Portable
Multithreaded
High Performance – JIT
Buzzwords glommed from the Core Java 2 book verbatim

11. FREE

12. Is Java Interpreted or Compiled?

13. 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!

14. Is Java Object Oriented?

15. Is Java Object Oriented?
YES!
Every bit of code in a Java program is in a “Class”
Code Reuse, Encapsulation, Polymorphism, Inheritance

17. DUKE!
Why? Who knows…

18. 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

19. 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)

20. 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”

21. If we were
lucky we
got
something
that looks
like this…

22. 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

23. 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.)

24. 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