Java

How to find, install and begin to use the Java programming

language.

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

A short look at some old school languages, BASIC, C and C++

It all begins in the sixties…

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.

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.

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”

Say goodbye to the seventies and welcome to a short

(but hopefully informative) history of the Java

programming language

Authentic SeventiesNerds

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

Java Buzzwords

Simple

Object Oriented

Architecture Neutral

Portable

Multithreaded

High Performance – JIT

Buzzwords glommed from the Core Java 2 book verbatim

FREE

Is Java Interpreted or Compiled?

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!

Is Java Object Oriented?

Is Java Object Oriented?

YES!

Every bit of code in a Java program is in a “Class”

Code Reuse, Encapsulation, Polymorphism, Inheritance

DUKE!Why? Who knows…

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

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)

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”

If we were lucky we

got something that looks like this…

Help on the Webhttp://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

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.)

THANK YOUhttp:\\remus.rutgers.edu\java\workshops\

Any questions or comments can be sent to me At biglars@cs.rutgers.edu

Be Good Now…

©2007 Rutgers University & Lars Sorensen